ANDREW HUBERMAN: Welcome to
the Huberman Lab podcast, where we discuss science
and science-based tools for everyday life. [MUSIC PLAYING] I'm Andrew Huberman,
and I'm a professor of neurobiology
and ophthalmology at Stanford School of Medicine. Today, we are
discussing breathing. Now, breathing is
something that we are all familiar with because, frankly,
we are all doing it right now. And we do it during our waking
states and while we are asleep. And most of us have probably
heard that breathing is essential to life. We hear that we can survive
without food for some period of time, maybe even
up to a month or more, that we can't survive
that long without water, but we could survive a
few days without water, depending on how well hydrated
we are when we go into that water deprivation and the heat
of the environment we happen to be in, but that we cannot
survive without breathing for more than a few minutes and
that if we cease to breathe, that our brain and our
bodily tissues will die. And, in fact, that is true. However, despite
everybody's knowledge that breathing is
essential to life, I don't think that
most people realize just how important
how we breathe is to our quality of life. And that includes our mental
health, our physical health, and what we call
performance, that is, our ability to
tap into skills, either physical or cognitive,
in ways that we would not be able to otherwise if we
are not breathing correctly. So today, we are going
to talk about what it is to breathe correctly, both
at rest, during sleep, in order to reduce our levels of
stress, in order to wake up or to become more
alert deliberately, and many, many other
things, including how to stop hiccuping. This is one of the most searched
for topics on the internet. Today, I will teach
you the one method that is actually linked to science. No, it does not involve
drinking a glass of water backwards from the
opposite side of the cup or holding your breath in
any kind of esoteric way. It actually relates to the
neural mechanisms, that is, the brain to body connections
that cause the hiccup. Hiccup is a spasm of
that neural circuit, and I'll teach you how to turn
off that neural circuit in one try. And that's not a
technique I developed. It's a technique that's
actually been known about for several centuries. And we now know the
underlying mechanism. So today's discussion
will give to you many tools that you can apply. All of these tools are, of
course, behavioral tools. They're completely zero cost. And in telling you
how those tools work, you'll learn a lot about
how the breathing, a.k.a. the respiratory, system,
works and how it interfaces with the other organs
and tissues of the body, in particular the brain. In fact, one of the
most important things to understand about breathing
right here at the outset is that breathing is unique
among brain and bodily functions in that it lies at the
interface between our conscious and our subconscious behavior. And it represents
a bridge literally in the brain between the
conscious and the subconscious. What do I mean by that? Well, breathing does not
require that we pay attention to our breathing
or that we are even aware that we are breathing. It will just carry on in the
background either normally or abnormally,
and I'll teach you what normal and abnormal
breathing is in a little bit. However, breathing is unique
among brain and bodily functions in that at any
moment, we can consciously take control of how we breathe. This is an absolutely
spectacular and highly unusual feature of brain function. For instance, your
digestion is carrying on in the background right
now whether or not you've had food recently or not. But you can't simply
control your digestion by thinking about it
in a particular way. In fact, most people can't
even control their thinking by trying to control
their thinking. That actually takes
some practice. It can be done-- a topic
for a future episode. However, breathing is unique. Breathing will carry on
involuntarily, subconsciously in the background,
as I said before. But if, at any moment, you want
to hold your breath or inhale more deeply or vigorously or
exhale longer than you inhale, you can do that. Very few, if any, other neural
circuits in your brain and body allow that level of control. And it turns out that level
of control is not an accident. It has been hypothesized that
by controlling breathing, the brain is actually
attempting to control its own state of mind. Now, the way this was originally
stated in a scientific research paper was a little
bit different. It was a little
bit physiological. The statement was, "The brain,
by regulating breathing, controls its own excitability." Excitability in the
context of neurobiology is how able the brain is to
take in new information or not, how able the brain is or not to
turn itself off to go to sleep and to regulate its own levels
of anxiety, focus, et cetera. If that seems a
little bit abstract, I'll make it simple for you. By changing your
pattern of breathing, you can very quickly change what
your brain is capable of doing. In fact, a little
bit later, I'll tell you that while
you inhale, you are far better at learning
and remembering information than during an exhale. And it is a very
significant difference. Does that mean you should
only inhale and not exhale? No, of course not. I'll teach you how to breathe
for the sake of learning and memory as well as
for physical performance and a number of other things. So hopefully I've been
able to highlight for you the importance of breathing
not just for life, because, yes, breathing
is essential for life, but that the subtleties
of how we breathe, the duration and
intensity of our inhales and our exhales, how long we
hold our breath between inhales and exhales, very critically
defines our state of mind and our state of body,
what we are able to do and what we are not able to do. And the great news is we
can control our breathing and, in doing so, control
our mental health, physical health, and performance. Before we begin, I'd
like to emphasize that this podcast is separate
from my teaching and research roles at Stanford. It is, however, part
of my desire and effort to bring zero cost to
consumer information about science and
science-related tools to the general public. In keeping with
that theme, I'd like to thank the sponsors
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Join.WHOOP.com/Huberman today and get your first month free. Let's talk about breathing. And, of course, we
breathe in order to bring oxygen into the body. But we also breathe to remove
certain things from our body, in particular carbon dioxide. So the main players
in today's discussion are going to be oxygen
and carbon dioxide. Now, a common misconception
is that oxygen is good and carbon dioxide is bad. That's simply not the case. Let's just take a step
back from that statement, and let's think about this. When we breathe
in, we are largely breathing in air in order to
bring oxygen into our body. And we can just stop
right there and say, why do we breathe at all? Why can't we just get oxygen
from the world around us? Well, it's because oxygen
can't diffuse through our skin into the deeper
cells of our body. Other single cell and
very simple organisms can actually bring
oxygen into their system without the need to breathe. But we have to breathe
in order to bring oxygen to the cells that
reside deep in our body. In particular, our
brain cells, which are the most metabolically
active cells in our body, require a lot of oxygen.
And those brain cells are sitting, of course,
in the brain, which is encased in the
cranial vault, the skull. And so oxygen can't simply
pass to those cells. So we need to have a system
that will deliver oxygen to those cells. We also need a system,
which turns out to be the breathing or
respiratory system, that can offload or remove the
gas that we call carbon dioxide, not because
carbon dioxide is bad but because too much of it
in our system is not good. In fact, much of
today's discussion will also center around
the common misconception that carbon dioxide is something
that we want to get rid of. You don't want to get rid of
too much carbon dioxide or else you can't actually get oxygen
to the cells and tissues of your body in
an efficient way. So you need oxygen and you need
carbon dioxide in your body. You also need to be able
to offload or remove carbon dioxide and bring in
oxygen in the correct ratios so that you can perform the
kind of mental functions and physical functions
that you want to. So if we just dial
out even further, we say, what are the key
components of breathing? What are the elements
within the body that allow us to bring oxygen
to the tissues and cells as is required and remove
carbon dioxide from the body as is required and yet keep
enough carbon dioxide around in order to allow
oxygen to do its thing? Well, that breathing or
respiratory apparatus has two major
components, and I'm going to just briefly
describe those. And as I do this, I really
want to highlight the fact that any time you're thinking
about biology and physiology in particular, whether or
not it's about the brain or the liver or
the gut microbiome, it's useful to categorize things
either as mechanical mechanisms or chemical mechanisms. What do I mean by that? Well, let's just take
the analogy of hunger. There are mechanical
mechanisms that tell us when we should eat. For instance, you have neurons,
nerve cells in your gut that signal how
stretched or nonstretched the walls of your
stomach are, how full or how empty your gut is,
and send that information to the brain to make you feel
to some extent hungry or not hungry. In general, when our
stomach is very full and especially if it's very
distended, even with liquid, it suppresses our hunger. Whereas when our stomach is
devoid of that mechanical pressure, especially
for a number of hours, it tends to trigger
hunger by signaling via neurons to the brain. In addition, there are chemical
signals that go from the gut to the brain. For instance, we have
neurons in our gut that can detect the
presence of amino acids from proteins that we eat,
fatty acids from the foods that we eat, the lipids,
and sugars, different forms of carbohydrate. The neurons in our gut
are paying attention to or respond to how much
amino acid, fatty acid, and carbohydrate is in
our gut and sends signals to the brain to either
stimulate or suppress hunger. So those are
chemical signals that are being passed
from gut to brain, and they work in parallel
with the mechanical signals. And this idea of
"in parallel with," again, is a very common
theme in biology, especially neuroscience. The term parallel pathways
refers to the fact that any time there's a
critical bodily function, it's very unlikely that just
one type of information, like just mechanical
information, is going to be used.
/ Almost always, it's going to be mechanical
and chemical information. I could pick a number
of other examples. For instance, if
you want to avoid damaging your skin or other
tissues of your body, which is essential to life, well, then
you have mechanical information about, for instance,
whether or not something is pinching or ready
to pierce your skin. That's mechanical information. It's sent via specific
neurons up to the brain to signal a retraction
reflex if you move your limb away from
wherever that intense pressure is coming. You also have chemical
sensing in your skin, the presence of things
that elicit a burn or that elicit itch or
that elicit extreme cold. All of that chemical
information is being signaled up to the
brain as well in parallel. So parallel pathways
is a common theme. So when we're thinking about
the respiration, a.k.a. the breathing,
system, we also need to look at the
mechanical system. What are the
different components of the nose, the mouth,
the lungs, et cetera, that allow oxygen to be
brought in and carbon dioxide to be removed from the
body but not too much carbon dioxide removed
to allow breathing to work as efficiently and
as optimally as possible? And then we also need to
look at the chemical systems of the lungs, the bloodstream,
and how different cells use oxygen and carbon
dioxide in order to understand that as well. If you can understand the
mechanical and chemical aspects of breathing, even
just at a top contour, well, then the
various tools that I discuss during today's
episode, such as the ability to calm yourself down most
quickly by doing what's called a physiological sigh-- I'll go into this in more
detail in a little bit, but this is two very deep
inhales through the nose. So the first one is a long
inhale [INHALES DEEPLY],, and then the second one after
that is [INHALES SHARPLY] a quick, sharp inhale to
maximally inflate your lungs, followed by a full exhale
through the mouth to lungs completely empty. So it's big inhale
through the nose, then short inhale
through the nose immediately after that in order
to maximally inflate the lungs, and then a long exhale
through the mouth until your lungs are empty. You will understand why that
particular pattern of breathing and not simply one
inhale or not simply an inhale through the nose
and an exhale through the nose as well is optimal for
reducing your stress quickly. That double inhale through the
nose followed by a long exhale through the mouth works to
reduce your levels of stress and lower your levels of
so-called autonomic arousal very fast in real time. And it works better than
any other known approach. It's not a hack. This is actually something
that your body has specific neural circuits
to do, and it actually performs during sleep on
a regular basis and even throughout the day, and that
you can perform voluntarily. And it works so well
to reduce stress very quickly not
because it brings in the maximum amount
of oxygen and removes the maximum amount of
carbon dioxide but, rather, because it optimally
balances oxygen and carbon dioxide. If you understand the
mechanical and chemical aspects of breathing, then you
will understand exactly why that particular
pattern of breathing, the so-called
physiological sigh, is the most efficient
way to rapidly reduce stress in real time. If you can understand the
mechanical and chemical aspects of breathing, you will
also understand why most people are overbreathing. That is, they're breathing
too often, even if they're breathing in a shallow manner. They're breathing too often. And they are blowing off
or removing too much carbon dioxide. And if you understand
that carbon dioxide is critical for the way
that oxygen is delivered from the bloodstream to
the tissues of the body, including the
brain, well, then it will make very good
sense as to why people who are
breathing too much don't actually experience all
the effects of elevated oxygen, but, rather, they're putting
their body into what's called a hypoxic state. They're not getting
enough oxygen to the tissues of their body,
in particular their brain. And this is true not just
for people who are obese or who suffer from sleep apnea,
although that's certainly the case, but for people
that have, believe it or not, certain personality types. We'll talk about breathing
and personality type and actually how
breathing has been shown to alter personality. That's right. Breathing can alter personality
in positive ways that allow anyone to show up to the
various social and nonsocial endeavors of their life
with more calm, more focus, alertness, and improve
their overall health. OK, so let's talk about
the mechanical components of breathing. It's really quite simple. You've got your nose, obviously,
and you've got your mouth. And a little bit
later, we'll talk about the incredible advantages
of being a nasal breather most of the time but also
the incredible advantages of using your mouth to breathe
both for inhales and exhales during particular
types of endeavors. And we'll get back to
that a little later. But for the meantime,
the only two ways to bring air into your
system are through your nose and through your mouth. We also have the larynx, which
is a rigid tissue or pipe that brings the air from the nose
and mouth down to the lungs. Now, that word rigid is
really important here because what we will soon learn
is that your lungs basically act like a pump. You sort of know this already. But these are two
big bags basically that can fill with air or
that can squeeze air out. Now, what most
people don't realize is that the lungs are not
just too big bags of air. Your lungs are actually too big
bags of air that inside of them have hundreds of
millions of little sacs that are called the
alveoli of the lungs. And by having those hundreds
of millions of little sacs, you increase the surface
area of the lungs. And by increasing
the surface area, you allow more oxygen to pass
from the air in your lungs into the bloodstream than if
you didn't have those sacs. And you allow more
carbon dioxide to move from the bloodstream
into those sacs of the lungs, and then when you exhale, the
carbon dioxide can be removed. So those little sacs we
call alveoli of the lungs are an important part
of the mechanical aspect of breathing we'll get
to a little bit later. So at a first pass, the
mechanical aspects of breathing are really straightforward. You can breathe
through your nose. You can through your mouth. It goes down through the larynx. I told you the larynx
is a rigid pipe. The lungs are not rigid. They can expand and
they can contract like a pump to bring
in air or to expel air. Keep in mind that
the lungs do not have any muscles themselves. So we need muscles that can
either squeeze the lungs or that will allow
the lungs to expand. And there are two general
groups of muscles that do that, and they are the diaphragm
and the so-called intercostal muscles. The diaphragm is a thin muscle
that sits below the lungs and above the liver. And when we inhale,
provided that we are using what's called
diaphragmatic breathing, that diaphragm contracts. And when it contracts,
it moves down, which allows more space for
the lungs to inflate with air. Now, the intercostal muscles are
the muscles between our ribs. A number of people probably
don't realize this. But your ribs, of
course, are bone, but in between those
bones, you have muscles. And the intercostal
muscles, when you inhale, contract, and that allows
your rib cage to move up and to expand a bit. And I think, again,
people probably don't realize that your
ribs are not fixed in place. They can actually get
further and closer apart from one another. So when you inhale, your
rib cage actually moves up. Sometimes the shoulders
will move up as well. And that's because those
intercostal muscles are contracting. Now, muscles can't
move on their own. They are controlled by nerves. So we've got the nose,
the mouth, the larynx, and the lungs. The lungs have all those
little alveoli in them. And as I told you,
we've got the diaphragm as a muscle to move
the lungs, and we have the intercostal muscles
to move the ribs, which can allow the lungs to expand. Again, we're just on the
mechanical components of breathing. But because muscles
can't move themselves, you should be asking,
what moves the muscles? And it's really nerves
that control muscles. So whether or not you're
contracting your biceps or you're walking and you're
contracting your quadriceps and your hamstrings
and your calf muscles, it's neurons, nerve
cells that control that. There's a specialized nerve
called the phrenic nerve, P-H-R-E-N-I-C, phrenic nerve,
that comes out of the neck. And when I say it comes out
of the neck, what I mean is that there are little neurons
that reside in the brainstem, in the back of your brain,
and they send little wires that we call axons down
and out of the neck. They go close to the heart
and a little bit behind it. And they go down, and
they form synapses. That is, they form connections
with the diaphragm. And when those neurons release
neurotransmitters, which are little chemicals,
the diaphragm contracts, and it moves down. So we say that the phrenic
nerve is a motor nerve. It's designed to move muscle. However, the phrenic nerve, like
a few other nerves in the body, is interesting in that it has
not just motor nerves in there, neurons that control the
contraction of muscles. It also can sense things,
has sensory neurons. So it also sends connections
down to the diaphragm and actually down deep
into the diaphragm and close to the liver. And note that I said
liver twice now already, and we're going to
get back to this later when we talk about
physical movement and cramps of the body. Those sensory neurons dive
deep into the diaphragm. And then they go
back up to the brain, and they allow you to sense
where the diaphragm is. So they're giving
information about where the diaphragm is in your body. Now, most of the time, you're
not paying attention to this. But right now, you
can actually try this. And I would encourage
you to do this. Diaphragmatic breathing
is, in many ways, the ideal way to breathe and
that it's the most efficient way to breathe. We'll talk about what
we mean exactly when we say breathing efficiency later. But the diaphragm
is designed to allow the lungs to expand or
to contract the lungs, to bring air into
the body or to remove carbon dioxide from the body. And if you want to
know whether or not you're using diaphragmatic
breathing, it's very simple. If you inhale-- probably best
to do this through the nose, but you could do it
through the mouth. If you inhale and your belly
moves outward on the inhale, well, then that phrenic nerve
is controlling your diaphragm properly. And then when you
exhale, your belly should go in just a little bit. That's diaphragmatic breathing. Now, diaphragmatic
breathing is talked about in the context of yoga. It's often talked about as a
way to calm down and so on. But diaphragmatic
breathing is just one mode by which your brain
and the phrenic nerve can control muscle,
the diaphragm, to control the mechanical
aspects of the lungs to bring in air and expel air. As I mentioned
before, you also have these muscles between your ribs
or the intercostal muscles. And there's a
separate set of nerves that allow those muscles to
contract and for your rib cage to expand in order to create
more room for your lungs to get larger and fill with
air or for your rib cage to contract a bit when
those muscles relax in order to expel air. I'd like to go on
record by saying that there is no rule that
diaphragmatic breathing is better than breathing
where your rib cage moves. This is a common misconception. People say, oh, if your
shoulders are going up and down and your rib cage is moving
while you're breathing, well, then you're
not breathing right. And if your belly goes out
and the rest of your body is still while you
breathe, well, then you're breathing correctly. I know of zero-- in fact, zero minus one data
to support that statement. You have multiple
parallel mechanisms to control the mechanics of
your lungs and for breathing. And when you're exerting
yourself very hard, you tend to use both
the intercostal muscles and your rib cage moving as
well as your diaphragm in order to bring in a lot of
oxygen and to offload a lot of carbon dioxide. And when you're
calmer, frankly, you could use
diaphragmatic breathing or you could use rib cage
type breathing in order to bring enough oxygen
into your system. There's no real data showing
that diaphragmatic breathing is somehow better or worse. However, being able to
mechanically control those independently or to combine
them and use them together is of tremendous power
toward regulating your mental and physical states. And we'll talk about how to
do that a little bit later. For right now, please
understand that you have these different
mechanical components that allow you to bring oxygen into
your system and to expel air and to thereby offload carbon
dioxide from your system. Again, we haven't talked about
the gas exchange of carbon dioxide and oxygen
and how that's happening in the bloodstream. We'll talk about that next. But the basic mechanical
components are pretty simple. Once again, just to review,
it's nose, mouth, larynx, lungs, alveoli within the lungs,
and then those two muscles, the diaphragm and the
intercostal muscles of the ribs. And one thing I
failed to mention is why it's so important that
that larynx be rigid, that it's a tube that is very rigid. And the reason for that is
that unlike the lungs, which you want to act as
sort of a bellow pump where you can deflate it and
inflate it in order to move air in and out, the larynx
needs to be rigid so that it doesn't collapse
while you're bringing air in and out. You can imagine that if it was
a very flimsy tube or the walls of the larynx were
very flimsy and thin, well, then you can imagine
breathing in very vigorously, and it would shut
like a tube that suddenly flattens on itself,
which would not be good. So the fact that
the larynx is rigid is actually a very crucial
part of this whole system. The other important
aspect of this system as it relates to the
mechanics of breathing is the fact that your
nose and your mouth have different
resistances to air. You can probably
notice this right now if you were to, for
instance, breathe in through your mouth
[INHALES] and only through your mouth
versus breathing through your nose [SNIFFS]. Some of you perhaps have
a harder time breathing in through your nose. By the way, it's
perfectly normal that one or the
other nostril would be harder to breathe through
or easier to breathe through and that switches
across the day. It has to do with the flow
of mucus and cerebrospinal fluid and intracranial pressure. Totally normal. Many people out
there think they have a deviated septum
who don't actually have a deviated septum. A little bit later,
we'll talk about how to repair a deviated septum
without surgery because that actually is possible
in many, not all, cases and is immensely
beneficial to do. But what we know is that
breathing in through the nose is a little bit harder,
and it's supposed to be a little bit harder. However, because it's a little
bit harder because there's more resistance, as we
say, you are actually able to draw more force into
these mechanical aspects of the breathing
apparatus and actually bring more air into your lungs. You can try this right now. Try breathing in through your
mouth to maximally inflate your lungs and try and do it
through mostly diaphragmatic breathing, just for
sake of example. In other words, try and
breathe in through your mouth. And as you do that, have your
belly expand and maximally inflate your lungs. I'll do it right now with you
so that we can do it together and I can prove to
everyone that I'm just as deficient in this as you are. [INHALES] OK, so I can inflate
my stomach doing that. But now try doing
it with your nose, and please do exhale before you
try doing it with your nose. With your nose, you're going
to feel more resistance, but you'll notice that you can
inflate it quite a bit further. [SNIFFS] And you'll feel your
entire cavity, your belly and maybe even in your lower
back, fill with some pressure. So the increased
resistance actually allows you to draw more
air into the system. This turns out to
be very important. And it also wipes away
a common misconception, which is if you're somebody
who has challenges breathing in through your nose, that somehow
you should avoid breathing in through your nose, actually,
quite the opposite is true. And we can go a
step further and say that if you have challenges
breathing in through your nose, chances are that's
because the increased resistance of breathing
in through your nose, provided it's not
completely occluded, is going to allow you to bring
more oxygen into your system. This will turn out to
be useful later when we explore different
techniques, for instance, not just to calm down
quickly but to elevate your energy quickly, to remove
a cramp during exercise, and a number of other
things that breathing can be used for that
can be immensely useful for mental and
physical challenges. I'd like to take a quick
break and acknowledge one of our sponsors,
Athletic Greens. Athletic Greens, now called AG1,
is a vitamin mineral probiotic drink that covers all of your
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gut microbiota that communicate with the brain, the
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supply of vitamin D3/K2. Again, that's
AthleticGreens.com/Huberman to get the five free travel
packs and the year's supply of vitamin D3/K2. So now let's talk about the
chemical aspects of breathing. And the two major players
in this discussion are oxygen, which all the cells
and tissues of your body need, and carbon dioxide,
which all the cells and tissues of your body need. In fact, carbon dioxide
plays critical roles in delivering oxygen
to your cells. And without carbon
dioxide, you're not going to get enough
oxygen to the cells and tissues of your body. That said, if carbon
dioxide levels are too high, that is very problematic. In fact, one of the ways that
one can reliably induce panic in anybody is to
have them breathe air that contains too
much carbon dioxide, so much so that for
people that lack a so-called
amygdala-- many of you have probably heard
of the amygdala. This is a brain area that's
associated with fear and threat detection. Even in people who
completely lack amygdalas on both sides of the brain
because they were removed because they had
epileptic seizures there and, therefore, those people are
completely unafraid of things that they ought to be
afraid of like heights, poisonous snakes, any
number of different things dangerous to humans,
well, if those people breathe an excess amount
of carbon dioxide, they immediately
have a panic attack. What that tells us
is that, again, there are parallel mechanisms,
there's redundancy in the system to protect ourselves from
having too much carbon dioxide in our system. So we need enough carbon dioxide
and enough oxygen in our system but not too much. The way that's accomplished is,
of course, we breathe in air. Our lungs inflate. And if you recall those
little alveoli of the lungs, those little sacs, oxygen can
actually move from the air into those little sacs and
then from those little sacs into the vasculature--
the vasculature are the capillaries, the veins,
and the arteries of the body-- because the walls of
those little alveoli are exceedingly thin, and they
have tons of little capillaries that go into them and
are all around them. So this is amazing, right? There's oxygen literally
passing from inside of these little
sacs in our lungs because we inhaled the
oxygen from the air into the bloodstream,
and then that oxygen gets bound up by
proteins in the blood, in particular hemoglobin. And hemoglobin then
delivers oxygen to the various cells
and tissues of the body. However, oxygen can't just
hop on hemoglobin and cruise along with hemoglobin until
it gets to, say, your brain and then hop off. It doesn't work that way. You require carbon
dioxide in order to liberate oxygen
from hemoglobin. Carbon dioxide has this
incredible property of actually being able to
change the shape of hemoglobin. Hemoglobin is shaped as a
sort of a cage around oxygen molecules. And when it's in
that cage shape, the oxygen can't be liberated. So you've got oxygen and
hemoglobin bound to one another moving through your bloodstream. But if a tissue
needs oxygen, there needs to be carbon dioxide
present to open up that cage. And that's what
carbon dioxide does. It allows that cage
to change shape, and then the oxygen
can be liberated and then can be
delivered to the tissues, whether or not that's brain
tissue or muscle tissue, so on and so forth. And so those are the
major chemical components of breathing. There are a few
other aspects related to the chemical
components of breathing, such as the fact that carbon
dioxide is strongly related to how acidic or how basic
your body is in general. So for instance, if carbon
dioxide levels go way down, your blood pH goes way up. That is, you become
more alkaline. Now, for many people, the word
pH and the whole concept of pH immediately starts to evoke
anxiety in and of itself. pH is actually very simple. You want the body basically
to be at a pH of about 7.4. There are some
regions of your body, in particular along the gut,
for which that number is importantly different in order
for digestion to work properly. You've all heard of the gut
microbiome, the little microbes that, provided you
have enough of them and they're diverse enough,
allow your brain and body to function optimally at the
level of immune system, hormone system, brain, et cetera. Well, in the gut, you
want the pH sometimes be slightly more acidic. Because when it's more
acidic, the little microbiota flourish far more than
if it were more basic. But basically, you want
the rest of the body to be at about pH 7.4. If carbon dioxide levels go to
low, the pH increases in a way that you might say,
oh, well, that's bad, but that actually
allows more oxygen to be available to the
tissues of your body, at least temporarily. We'll talk about this
a bit more later. If I'm losing any of
you, just hang in there because we're almost done
with this whole business of the mechanics and the
chemistry of breathing, and then we can get into the
tools and revisit some of this later to clean up any
misunderstandings that may have arisen. But as we're talking about
carbon dioxide over and over again and how key it is to have
carbon dioxide and the problems with it going too
high to low, you should probably be asking
yourself, what actually makes carbon dioxide go too low? We know that we
breathe in oxygen, and then it can pass from
the lungs and the alveoli into the bloodstream and that we
need carbon dioxide to liberate oxygen from the
hemoglobin into the cells and tissues of the body. And we know that
when we exhale-- well, actually, I haven't
told you this yet. But you should know
that when you exhale, carbon dioxide is actually
taken from the bloodstream back into the
alveoli of the lungs. And then when you exhale, it's
expelled through your mouth or through your nose
out into the world. So the way I just described all
that-- inhale, bring in oxygen, exhale, expel carbon dioxide-- pretty straightforward, right? Indeed, it is. And it also tells
you that were you to exhale a lot more or
a lot more vigorously, you would expel
more carbon dioxide. And in fact, that's
exactly the way it works. When you hyperventilate,
of course, you are inhaling more than
usual, but you are also exhaling more than usual. So you're, of course, bringing
in more air and oxygen to your body. But you're also removing more
carbon dioxide from your body than normal. Carbon dioxide, because of the
ways that it regulates brain state-- in fact, the way
in which it regulates the excitability, literally
the ability of your neurons to engage electrically or not-- it can create states of
panic and anxiety, which is why when you
hyperventilate, you feel an increase
in anxiety, or when you feel an increase in
anxiety, you hyperventilate. It's a reciprocal relationship. In fact, I don't want
anyone who has anxiety or who has panic
attacks to try this now. But for most people,
it's probably safe as long as you're not driving
or doing something mechanical or operating machinery, that is. Probably safe to do 25 or
30 deep inhales and exhales. And you'll notice that
by about breath 10, you'll start to feel
tingly, and you'll probably feel a little bit more alert. And, again, if you have anxiety
or panic attack tendencies, please don't do this. But you will feel an increase
in so-called autonomic arousal, an increase in the activity
of your overall sympathetic nervous system, which has
nothing to do with sympathy, has everything to
do with alertness. You'll actually deploy
adrenaline from your adrenals. So I'll just do this now. You can try this now, again,
provided you're in a safe place and you don't have anxiety
or panic attack tendencies. You would just breathe
in through your nose and out through your mouth. Remember, we're breathing
in more and more vigorously, and we're exhaling more and
more vigorously than we normally would. It goes something like this. [INHALING, EXHALING] Now, by breath 8
or 9 or 10, you'll notice that your body
starts to heat up. That's due to a
couple of things, mainly the release of
adrenaline from your adrenals. I'm already feeling a
little bit lightheaded. The lightheadedness is actually
because your vasculature, the capillaries and veins
and, to some extent, even the arteries of your body
and particularly in your brain, are actually starting
to constrict. So you're cutting off
blood flow to the brain. Why? Well, because carbon dioxide
actually is a vasodilator. Normally, it exists in your
body to keep capillaries, veins, and arteries dilated to allow
blood to pass through them. When you hyperventilate,
sure, you're bringing in a lot
of oxygen, which you think would make you more
alert, and, indeed, it does. But you are also expelling
a lot more carbon dioxide than you normally would. And that's causing
some vasoconstriction, and you're going
to start feeling tingly in the periphery,
in your fingers and toes perhaps or your legs. You will also notice that you're
feeling more alert in the brain but that you might start
to feel a bit of anxiety. So hyperventilation, yes,
brings in more oxygen, also removes more
carbon dioxide. The removal of
excess carbon dioxide puts you into a state that's
called hypocapnic, hypoxia. Hypoxia is reduced levels of
oxygen relative to normal. Hypocapnia is reduced
levels of carbon dioxide relative to normal. And it is those reduced
levels of carbon dioxide that are largely responsible
for that elevation in energy and at the same time
a feeling of a bit of anxiety, the construction of
the microvasculature in the brain and
body, and therefore the feelings of
being kind of tingly and having kind of
an urgency to move. OK, so by now, it
should be clear that we need both oxygen
and carbon dioxide. And across the course
of this episode, I will explain how to adjust
those ratios of oxygen to carbon dioxide depending on
what your immediate needs are and what you plan to
do next, whether or not that's sleep or exercise
or mental work, et cetera. Before going any
further, however, there is something I want to touch on. Because even though not
everyone will experience this, I think enough
people experience it that it is of
interest, and now's the right time to touch into
what happens when you go up to a very high altitude, meaning
why it's hard to breathe when you get up to high altitudes. So if you're close
to sea level, you are getting out of the
optimal balance of oxygen in the air you breathe. As you ascend in
altitude-- so let's say you go to 6,000
feet or 10,000 or maybe even 11,000
feet above sea level. Or maybe you're one of
those rare individuals that climbs Denali, or you
climb Mount Everest, and you get up there, and you
notice that most people are going to wear an oxygen mask. Why is it that you need an
oxygen mask at those very high altitudes or when people
do these very high altitude skydives that they need
oxygen way up high? Well, a lot of people will say,
oh, there's not much oxygen up there. The air is thinner. OK, well, perhaps a better
way to think about it is that, remember
when we were talking about the mechanical aspects
of breathing and the fact that the lungs don't
really move themselves, that they have the
muscles, the diaphragm and the intercostal
muscles to move them? Well, a lot of the reason why
your lungs can fill so readily with air is that when you don't
have much air in your lungs, there's very low air pressure in
your lungs relative to outside you. So what we mean
then is if you were to open up your mouth
[INHALES] or your nose and breathe in, that is,
breathe in through your nose or mouth, what's
going to happen is air is going to move from
high pressure to low pressure. So it's very easy
to fill your lungs. Even though you
need those muscles to move the various
things around that allow your lungs
to fill, the air is going to go from high
pressure to low pressure. So [INHALES] for those
of you listening, I just took a big
inhale through my nose. And then when you exhale, you're
basically taking the lungs from a state in
which the pressure is really high in the
lungs, high pressure, like a balloon that's full-- and the pressure in your
lungs when your lungs are full is higher than the air outside. So it's pretty easy
[EXHALES] to expel that air through the nose or mouth. When you're at high altitudes,
the air pressure is lower. And so what happens is when
the air pressure is lower outside your body and your
lungs are not full of air, you don't have that
really steep gradient of high pressure
outside the body to low pressure
inside your lungs. And so you actually have
to put a lot more effort into breathing air
into your lungs. You have to really
exert a lot of force. You have to get the diaphragm,
those intercostal muscles working really hard. You might even find that
your shoulders are lifting with each breath [INHALES]
because you really have to generate a lot of
force to get enough air and oxygen into your lungs. Now, an important
principle to understand is that in humans, and
in some other species, but really what we're
talking about now is humans, when you inhale,
that's an active process. You really need to
use those muscles of the intercostals
and the diaphragm in order to inflate the lungs. But the whole process
is made easier when air pressure
outside your body is higher than it
is in your lungs because then they're going
to fill up really readily. Exhaling, at least for
humans, is a passive thing. You just have to
relax the diaphragm and relax the intercostals and
let the rib cage kind of fall back to its original position. So inhaling is active,
and exhaling is passive. And so what happens is if
you're at a high altitude and the air pressure
is very low, then you have to
put a lot of energy into breathing air
into your lungs to get an equivalent amount
of oxygen into your lungs and then into the bloodstream. So that's why when you arrive
at a high altitude location, for the first few days, you're
going to feel lightheaded maybe a headache. You're also going to have
more buildup of carbon dioxide in your system. And so the whole balance of
oxygen and carbon dioxide is going to be disrupted. I mention all that
because, yes, indeed, there are some changes in
the atmospheric gases at high altitudes,
and that can impact how much oxygen you can
bring into your system, into your tissues. But I've heard many explanations
of why it's hard to breathe or why you feel
lousy at altitude. Well, you just
discovered one reason, which is that you don't have
that steep high pressure to low pressure gradient
from the outside of the body into the inside of the body. The converse is also true. If you've been at
altitude for a few days and you've had the opportunity
to adjust-- a lot of athletes, for instance, will
go train at altitude. It's hard for them in
the first days or weeks, and then they get really
good at training at altitude. There are a number of
different adaptations that occur in terms of
the amount of oxygen that can be carried in
the blood by hemoglobin and the interactions between
carbon dioxide and hemoglobin and oxygen that
allow more oxygen to be delivered to the tissues,
such that, at altitude, you can function just normally. But if you then move very
quickly from altitude-- say, you've been training at
8,000 feet or 10,000 feet. You've been hiking up at that
high level, and you've adapted, and you come down to sea level. Well, for about
two to five days, you're going to feel
like an absolute beast. You're going to be able
to essentially deliver far more oxygen to your
muscles per breath. In part, that is
because of the way that the hemoglobin and the
oxygen that it's carrying has been altered when you
were at high altitude. But it's also because when you
were at that high altitude, those intercostal muscles
and those diaphragms got trained up quite a bit and
allowed you to generate more air volume for every breath. In other words, those
muscles got stronger, and you got more efficient
at driving the phrenic nerve consciously to [INHALES] really
breathe in a lot of oxygen so you don't feel lightheaded,
headache, et cetera. OK, so that's a little
bit of an aside. But it's an important aside,
I believe, because, A, it answers a question
a lot of people ask and they a lot of people
wonder about and, B, because it incorporates both the
mechanical aspects of breathing and the chemical
aspects of breathing. I realize it's a little bit
of a unusual circumstance. But now if anyone
asks you why it's hard to breathe at
altitude, you know it has to do with this
lack of a high pressure to low pressure
gradient across the body and with the
atmosphere outside you. It's also an opportunity
for me to say that if you do find
yourself at altitude and you have a headache or
you're feeling like you just can't catch your breath,
spending some time really consciously trying to draw
in larger breaths of air, as much as that
might seem fatiguing and you'll be short of
breath, it will allow you to adapt more quickly. And a little bit
later in the episode, we'll touch on a few
methods, including deliberate hyperventilation
combined with some breath holds, that can allow
you to deliver more oxygen to the cells
immediately upon arriving at altitude so you
don't get quite as much headache,
disorientation, and so on. So leaving breathing
at altitude aside let's all come back down to the
same conceptual level. We can ask ourselves,
for instance, what is healthy breathing, and
what is unhealthy breathing? And the first place
we want to tackle this is within the context of sleep. So when we go to sleep at
night, we continue to breathe. That's no surprise. If we didn't, we would
die during sleep. However, there is
a large fraction of the population that
underbreathes during sleep. They're not taking deep enough
or frequent enough breaths. And therefore, they
are experiencing what's called sleep apnea. They are becoming
hypoxic, hypo-oxic. There's less oxygen being
brought into their system than is necessary. People that are
carrying excess weight, either fat weight or
muscle weight or both, are more prone to
nighttime sleep apnea. However, there are
a lot of people who are not overweight who
also experience sleep apnea. How do you know if you're
experiencing sleep apnea? Well, first of all,
excessive daytime sleepiness and excessive daytime
anxiety combined with daytime
sleepiness is one sign that you might be
suffering from sleep apnea. The other thing is if
you happen to snore, it's very likely that you
are experiencing sleep apnea. And I should mention that sleep
apnea is a very serious health concern. It greatly increases
the probability of a cardiovascular event,
heart attack, stroke. It is a precursor or
sometimes the direct cause of sexual dysfunction
in males and females. Cognitive dysfunction
during the daytime. It can exacerbate the
effects of dementia, whether or not it's age-related
dementia of the normal sort or Alzheimer's type
dementia, which is an acceleration of
age-related cognitive decline. If you're somebody who
has had a traumatic brain injury, if you're
experiencing a lot of stress, sleep apnea is going
to greatly disrupt the amount of oxygen brought
in to your brain and body during sleep and
is going to lead to a number of nighttime
and daytime issues. So it's something that
really needs to be addressed. And we'll get into
this a bit more later. But since I raised
it as a problem, I do want to raise the solution. One of the major
treatments for sleep apnea is that people will get
a CPAP device, which is this face mask and a machine
that they'll sleep with. And while those can
be very effective, not everyone needs a CPAP. One of the more common
methods nowadays that's being used to
treat sleep apnea, which is purely behavioral,
an intervention, and is essentially zero
cost, is that people are starting to
shift deliberately to nasal breathing
during sleep because of the additional resistance
of nasal breathing and because of the
fact that there's far less tendency if
any, excuse me, to snore when nasal breathing. Taping the mouth shut using
medical tape prior to sleep-- excuse me. Putting medical tape on the
mouth prior to going to sleep and then sleeping all night
with medical tape on the mouth is one way that people can learn
to nasal breathe during sleep and can greatly offset a
lot of sleep apnea, snoring, and sleep-related issues. A number of people
don't want to or don't feel safe putting medical tape
on their mouth prior to sleep. For some reason, they think
they're going to suffocate. But, of course,
you would wake up if you start to run out
of air at any moment. So that's not so much a concern. But what they'll do
is they will start to use pure nasal breathing
during any type of exercise or even just for some period
of time walking during the day or while working. And, again, later, we'll get
into the enormous benefits of shifting to pure nasal
breathing when not exercising hard, meaning at a rate
that you could normally hold a conversation-- although
if you're pure nasal breathing, you won't be holding
that conversation-- or when simply doing work
or any number of things that are of low intensity. You can train your system to
become a better nasal breather during the daytime
through these deliberate actions of taping the mouth
shut or just being conscious of keeping your mouth shut. And that, in addition to having
a number of positive health and aesthetic effects
during the daytime, is known to also transfer to
nighttime breathing patterns and allow people to become
nasal breathers as opposed to mouth breathers during
sleep and to snore less and to have less sleep apnea. Again, if you have
severe sleep apnea, you probably do need
to check out a CPAP. You should talk
to your physician. But for people who have
minor sleep apnea or sleep apnea that's starting
to take hold, these other methods of shifting
to becoming a nasal breather are going to be far more
beneficial and far more cost effective than going all the way
to the CPAP, which, by the way, doesn't really teach you
how to breathe properly as much as it does adjust the
airflow going into your system. That's an important point,
that when you shift from mouth to nasal breathing
during sleep, you're actually learning and
training your system to breathe properly. And when I say
learning and training your system to breathe
properly, what do I mean? Let's put some scientific
and mechanistic meat on that. We already talked about the
phrenic nerve, this nerve that innervates the diaphragm
and that allows for the lungs to fill up because of the
movement of the diaphragm. What we didn't talk
about, however, were the brain
centers that actually control the phrenic nerve
and control breathing. Knowing about these two
brain areas and what they do is extremely important, not just
for understanding the content of this episode but for
understanding all of the tools that we'll discuss and, indeed,
your general health as it relates to respiration. So there are basically
two areas of the brain that control breathing. The first is called the
pre-Botzinger complex. You don't have to worry
about the name so much. Just know that it was named
after a bottle of wine and that it was discovered by
the great Jack Feldman, who's a professor of neuroscience at
the University of California, Los Angeles. This is one of the most
fundamental discoveries in all of neuroscience
in the last hundred years or more because this brain area
that Jack and his colleagues discovered controls all aspects
of breathing that are rhythmic, that is, when inhales
follow exhales follow inhales follow exhales. That's all controlled
by a small set of neurons in this
brainstem area, so around the
region of the neck, called the
pre-Botzinger complex. And we really owe
a debt of gratitude to Jack and his colleagues
for discovering that area because it's involved in
everything from breathing when we're asleep to
breathing when we're not thinking about our breathing. It may have a role-- that is, when its
function is disrupted, it may cause things like
sudden infant death syndrome. Believe it or not,
it can explain in large part many of the deaths
related to the opioid crisis because exogenous opioids
like fentanyl and other sorts of drugs, which are
opioids obviously, bind to opioid receptors on
that structure and shut it down. Now, keep in mind these
neurons are designed to be incredibly robust and
are designed to fire inhale, exhale, inhale, exhale no
matter if we're awake or aware, unaware or asleep
to keep us alive. Exogenous opioids like
fentanyl and drugs that are similar to that
can shut down that structure because it's rich with
these opioid receptors. So it binds to that,
and it shuts off the pre-Botzinger
complex, which is the major cause
of death of people who die from opioid overdoses. I think a lot of people
don't realize that. They think, oh, the opioids
must shut off the brain or shut down the heart. No, it shuts down breathing. So Jack's discovery
no doubt will lead to some important things
as it relates to addiction, and hopefully I think we frankly
can expect that it's also going to eventually lead to
ways to prevent death in people using opioids or
other types of drugs, maybe by blocking
opioid receptors in pre-Botzinger
complex using things like naltrexone, et cetera. In any event,
pre-Botzinger complex is controlling inhale, exhale,
inhale, exhale patterns of breathing. The other brain center
controlling breathing, again, through the phrenic nerve-- it all converges and goes
out through the phrenic nerve in these intercostal muscles-- is the so-called
parafacial nucleus. And the parafacial nucleus
is involved in patterns of breathing where there is not
an inhale followed by exhale, inhale followed by exhale--
that is, it's not rhythmic, one than the other-- but, rather, where there
is a doubling up of inhales or a doubling up of exhales or
a deliberate pause in breathing, so inhale, pause, exhale, pause,
inhale, pause, exhale, pause, this sort of thing. A little bit later, we'll
talk about a pattern of breathing called
box breathing, which has very specific and
useful applications, in particular for
adjusting anxiety. And in that case, it involves
going from rhythmic breathing of inhale, inhale,
inhale, exhale, that is, relying on the pre-Botzinger
complex neurons, to reliance on the parafacial
nucleus neurons and box breathing, just to give
away what's probably already obvious, as you inhale,
hold, exhale, hold, and repeat. And that pattern of
breathing, even though it's rhythmic in nature because
inhales precede exhales precede inhales and so on, there's
a deliberate breath hold inserted there. So anytime we're taking
conscious control of our breathing, the parafacial
nucleus is getting involved. Now, you don't have to assume
that the parafacial nucleus is the only way in which we
take conscious control of our breathing. We can also take control of
the pre-Botzinger complex. You can do that right now. So for instance,
you are breathing in some specific pattern
now that, unless you're speaking or eating, no doubt
is going to involve inhales followed by exhales. But you could, for
instance, decide that, yes, inhales are active
and exhales are passive. But now you're going to make
the exhales active as well. So rather than just inhale and
then let your lungs deflate, you could inhale [INHALES]
and then force the air out. [EXHALES] That's going to
represent a conscious taking over of control of the
pre-Botzinger complex. And so the reason I'm giving
this mechanistic detail is, A, it's super important if you
want to understand all the tools related to breathing. B, it's actually a
pretty simple system. Even though the areas
have fancy names like pre-Botzinger
or parafacial, it's pretty straightforward. You have one area that
controls rhythmic breathing-- inhale follows exhales-- and the
other area which gets involved in breathing any time
you start doubling up on inhales or exhales. In fact, the parafacial
nucleus is the one that you're relying on
while you speak in order to make sure that you
still get enough oxygen. It's also the one
that you will use if you incorporate the
physiological sigh or box breathing. And, frankly, most
of the time, you're using both of these circuits
or these brain systems, parafacial and
pre-Botzinger, in parallel. Again, biology loves
parallel systems, especially for
things that are so critical that if we didn't
do them, we would die, like breathing. And so it makes sense that
we have two different brain structures that control this. So now you have an understanding
of the mechanical control of breathing, that is,
the different parts within the parts list that
are involved in breathing, everything from nose to mouth
to alveoli, the lungs, et cetera, and the muscles
involved in moving the lungs. You understand, I like to think,
a bit about bringing oxygen in and removing carbon dioxide
but not so much carbon dioxide that you can't actually use
the oxygen that you have. And you know about
two brain centers, one controlling rhythmic
breathing and one that controls nonrhythmic breathing. I want to repeat something that
I said a little bit earlier as well, which is that
breathing is incredible because it represents
the interface between conscious and
subconscious control over your not just body,
not just your lungs, but that how you breathe
influences your brain state. So by using your
brain consciously to control your breathing,
you are using your brain to control your brain. The best way I've ever
heard this described was from a beautiful,
I should say now classic paper in The Journal
of Physiology, published in 1988 from
Balestrino and Somjen, where the final line of
their summary intro states, "The brain, by
regulating breathing, controls its own excitability." And just to remind
those of you that don't remember what
excitability is, excitability is the threshold
at which a given neuron, nerve cell can be active or not. So when we breathe a certain
way, the neurons of our brain are more likely to get engaged. They're more likely
to be active. And when we breathe
in other ways, our brain becomes
harder to activate. Its excitability is reduced. Now, you might think
excitability is a great thing. You always want your
brain to be excitable. But that's actually
not the case. And, in fact, that
very statement that Balestrino
and Somjen made led to a number of
other investigations that were really
important in defining how if people
overbreathe, that is, if they hyperventilate, at
rest, they expel, that is, they exhale too much
carbon dioxide, what that classic paper by
Balestrino and Somjen led to was a number of
different investigations in humans looking at how
different patterns of breathing impact the overall state of
the brain and the ability of the brain to
respond to certain what are called sensory stimuli. Keep in mind that your
brain is always active. The neurons are firing at low
level, low level, low level. But when you see something
or hear something, or you want to
focus on something, or you want to exercise or
really listen to something or learn, certain
circuits in your brain need to be more active
than everything else. That is, there needs to
be really high what's called signal to noise. There's always a lot of noise
and chatter in the background, just like the chatter
at a cocktail party or at a stadium event. In order to really pay
attention, focus, learn, all the incredible things
that the brain can do, you need that signal
to get above the noise. There's a beautiful
paper that asks, how does the pattern of
breathing, in particular, how does overbreathing, change
the patterns of activity in the brain? This is a paper
entitled "Effects of Voluntary Hyperventilation
on Cortical Sensory Responses." And I will provide a link to
the study in the show note captions. It's a somewhat
complicated paper if you look at all
the detailed analyzes. However, the takeaway from this
paper is exquisitely simple and I also believe
incredibly important. Basically, what it
showed is that when people hyperventilate,
they expel, that is, they exhale more carbon dioxide
than they would normally. So they become what's
called hypocapnic, OK? Carbon dioxide levels
are low in the blood. And over a short
period of time, they become low in the
tissues of the body. When that carbon
dioxide level drops low, you would say, OK,
well, you're still bringing in a lot of
oxygen, because these people are hyperventilating. So they should
feel really alert. And, indeed, that's
what happens. The people feel very alert. However, because
they're not bringing enough carbon dioxide in
or, rather, the proper way to say it would be because
they're overbreathing, exhaling too much, they are
not retaining or keeping in enough carbon dioxide. Well, then that lack
of carbon dioxide means that the oxygen
that they are breathing in can't be liberated
from the hemoglobin, can't get to the brain. And what they observe
is about a 30% to 40% reduction in the
amount of oxygen that's being delivered to the brain. And the reduction
in carbon dioxide also prevents some of the
normal patterns of vasodilation, the dilating, the opening
up of the capillaries, so, again, less blood flow. But most importantly, as
it's shown in this paper, the brain overall
becomes hyperexcitable. It's as if it's being starved
of oxygen and blood flow. And all the neurons in
a very nonspecific way start increasing
their firing levels. So the background activity
is getting louder and louder. It's like the rumble or the
noise of a crowd at a stadium. And as a consequence, the
sensory input from a sound or from a touch or from some
other event in the world doesn't get above the noise. What this means is that
when we hyperventilate, because we aren't retaining
enough carbon dioxide, we are not getting enough
oxygen to the tissues that need oxygen. And as a
consequence of that, the brain becomes hyperexcitable. We actually know that there's
an increase in anxiety. And we become less
good, less efficient at detecting things
in our environment. So we're not processing
information as well at all. The noise goes up, and
the signal goes down. Again, incredibly
important set of findings. I should also mention
that hyperventilation is one way that, in
the laboratory anyway or in neurosurgery
units for some time, physicians would evoke seizure
in seizure-prone patients. The reason that works is
exactly the explanation I just gave you. Seizure is a excitability
of the brain, not enough inhibition or suppression
of the overall circuitry. So you get these waves or these
storms of electrical activity. Low levels of carbon
dioxide in the brain because of low levels of carbon
dioxide in the blood are one of the major
triggers for seizures. Now, I realize that most
people listening to this are not epileptic. But nonetheless, this
brings us all back to this question of what is
normal healthy breathing. As I mentioned before,
normal healthy breathing is breathing about six
liters of air per minute. But of course, most
of us don't think in terms of liters
of air, and we're not going to measure our lung
capacity, at least most of us aren't going to do that. Basically, if you are taking
relatively shallow breaths and you're just sitting there
working or maybe even walking slowly, again, not
talking or engaging in any kind of speech
or eating, chances are six liters of air per minute
is about 12 shallowish breaths. And when I say
shallow, I don't mean breathing [INHALES SHALLOWLY]
like a little bunny rabbit or something like that. I just mean casually
breathing in out, in out. The studies that have explored
the breathing patterns in large populations of
individuals who are not suffering necessarily from
any one specific ailment have shown that most
people breathe far too much per minute, that
they're engaging in anywhere from
15 to 20 or even 30 shallow breaths per minute. So they are vastly
overbreathing relative to how they should be breathing. Now, of course, if you
breathe more deeply, so you take a vigorous
inhale [INHALES] and then you expel
that air, well, then to get six liters of air
into your system per minute, you're probably only going to
need somewhere between four and six breaths in order to
get that six liters per minute. Now, the total
time that it takes to do that inhale and exhale
isn't that much longer than a shallow breath, provided
you're not deliberately breathing quickly during
those shallow breaths. So then you say, well, how is
it that normal healthy breathing that delivers the appropriate
amount of carbon dioxide into the system
and doesn't expel, doesn't exhale too
much carbon dioxide-- how are we supposed to
do that normal breathing? Are you supposed to
breathe four times and then hold your breath
until the minute passes? No. What you find is that the
correct pattern of breathing is going to involve two things. First of all, nasal breathing,
because of the resistance it provides through the nose
that we talked about earlier, is going to deliver more
oxygen into your system. You're going to be able
to generate more air pressure to fill your lungs. That greater air pressure is
going to take longer to exhale. So already we're increasing
the amount of time that each breath
is going to take. And also what you find
is that people that are breathing in the proper
healthy manner, that is, that are balancing
oxygen and carbon dioxide in the
proper ways, are also taking pauses between breaths. This is extremely important. Because even though we
have a brain center, the pre-Botzinger complex, that
can control or, I should say, does control inhale-exhale
rhythmic breathing, those pauses between breaths
are not always present and, in fact, often
are not present from people's baseline
breathing patterns. As a consequence,
they overbreathe. And as I told you before,
when people overbreathe, their brain becomes
hyperexcitable at the level of the
background noise. And yet they are less efficient
at detecting and learning information. We'll get into the
specific studies that really illustrate the
learning aspect a bit later. But they are less efficient
at detecting and learning information, at focusing,
and so on as a consequence of this overbreathing
and the hyperexcitability that it causes. Now, of course, that's
also just emphasizing the effects of
overbreathing and lack of carbon dioxide on the brain. There are hundreds,
if not thousands of studies showing that when
we don't have enough carbon dioxide in the
tissues of our body, that's also problematic for
all the tissues-- the liver, the lungs themselves, the
stomach, et cetera-- that relate largely to shifts
in pH because of the fact that carbon dioxide
strongly regulates the acidity, alkalinity of
the blood and the tissues that that blood
supplies nutrients to, including carbon dioxide. So the basic
takeaway here is you want to breathe in a
healthy manner at rest. And the best way to do that
is to spend some time-- and it doesn't take much,
maybe a minute or so each day-- paying attention to how quickly
you are breathing per minute when you are simply at rest,
when you're making coffee in the morning, when you're
sitting down to read, when you're on social media. Chronically holding
your breath isn't good but neither is overbreathing. And, again, every study that has
examined the typical patterns of breathing and
patterns of breathing that show up as
normal and abnormal has found that more
often than not, during the nighttime,
people are underbreathing. And in the daytime,
they are overbreathing. They're hyperventilating. I'd like to just
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InsideTracker.com/Huberman to get 20% off. So next, I'd like
to address what you can do about your normal
patterns of breathing, that is, how you or
anyone can adjust their normal patterns of
breathing from an unhealthy to an unhealthy state. But the first thing we
have to do, of course, is determine whether
or not you're already breathing in an unhealthy
or in a healthy way. And, again, when I say
healthy or unhealthy, I mean, are you overbreathing? Are you underbreathing? Are you delivering
the appropriate ratios of oxygen and carbon
dioxide to the tissues of your brain and body? In order to do this, we're
going to do a simple test. Again, please
don't do this while driving or operating heavy
machinery or near water of any kind. But assuming that you're not
doing any of those things, I encourage you to
sit down, certainly not lie down but just sit down. I suppose you also
could do it standing. And we are going to do what's
called the carbon dioxide tolerance test. The carbon dioxide
tolerance test is a sort of back
of the envelope measure of how well you are
managing carbon dioxide, that is, how well you can
control your breathing at both the mechanical
and the chemical level. It's a very simple test. What you're going to do
is for the next 10 seconds or so while I'm speaking, you're
just going to breathe normally. Now, again and again
throughout this episode, I'm going to encourage you to
be a nasal breather whenever possible. But of course, there are
instances in which you want to engage mouth breathing. But for the time
being, as I continue to blab on for the
next few seconds, just inhale through your nose,
exhale through your nose. You don't have to deliberately
slow your breathing or increase the cadence
of your breathing. However, in that
time, you're also going to want to find some
sort of time measuring device, like could be your phone
or it could be a stopwatch. What I'm going to ask you
to do in a few minutes is I'm going to ask you to
inhale through your nose as deeply as you possibly can. That is, you're going to fill
your lungs as much as you can through your nose. And then start a
timer and measure how long it takes for you
to deliberately control that exhale until
your lungs are empty. So this is going to
be a controlled exhale through the nose after
a big deep breath. But for the time
being, keep breathing at a kind of calm,
regular cadence. So you can find that time
measuring device now, or you can come back to
it later if you like. When I say inhale, you're going
to inhale as deeply as you can through your nose, remembering
that the diaphragm can really help you here to get a
deep inhale by having your belly move out
while you inhale. And then when I
say start, you're going to measure the
time that it takes to do a complete lungs empty exhale. In fact, I'll
measure it for you. This will be one of the rare
instances in this podcast where there's going to be
a long period of silence as I measure something. So I've got a stopwatch here. So please prepare to do the big
inhale and start inhaling now. So inhale as deeply as
you can through your nose. Fill your lungs as
much as you can. OK? Now start, meaning
slowly control the exhale through your nose. You're trying to let that air
out as slowly as possible. And I'm just going to call out
every 10 or 15 seconds or so. And you want to note when
your lungs are empty. I know you can hold your
breath with your lungs empty. That is not an accurate measure. 15 seconds. It is important that when
note your lungs are empty and that you're trying to
control the exhale as much as possible so that you don't
arrive at that lungs empty time too quickly. I'll explain what
too quickly means. 30 seconds. OK, for those of you that have
already reached lungs empty, please go back to
breathing normally. For those of you
that haven't, you can hang in here a little
longer if you're still discarding that air. 45 seconds. And we're rounding toward
a minute, not quite there. Some of you are probably
still letting out that air. I want to point out
none of this has to do with cardiovascular
fitness level, at least not in any kind of direct way. And 60 seconds. And I realize there will
be a small subset of you out there that are
still expelling your air in a slow lungs-- slow exhale manner
through the nose. OK, so what we just did is a
back of the envelope carbon dioxide discard rate if
you need to pause this and go back and try
it again you just want to time how
long it takes you to go from lungs full
to lungs empty, again, with the full understanding I
know that you can all sit there like beasts and hold your
breath with your lungs empty. But please don't do that
because that's not going has been informative for
what I'm telling you now. What I'm going to
tell you now is that if it took you 20 seconds
or less to expel all your air, that is, you couldn't
extend that exhale longer than 20 seconds, in a kind
of back of the envelope way, we can say that have a
relatively brief or low carbon dioxide tolerance. If it took you somewhere between
25 and 40, maybe 45 seconds to expel all your
air, that is, you could control that exhale for
about 45 seconds or 30 seconds, then you have a moderate level
of carbon dioxide tolerance. And if, for instance, you
were able to go 50 seconds or longer for that discard
until you hit lungs empty, you have a fairly high degree
of carbon dioxide tolerance. Now, here's the deal. If you had low carbon
dioxide tolerance, that is, you're 20 seconds
or less, you're going to write down
the number three. If you had moderate levels
of carbon dioxide tolerance, you're going to write
down the number five. or you could even
put five to six. And then if you are in
that bracket of people that was able to discard your
air over a period of 50 seconds or more, you're going to
write down the number 8 to 10. OK? Now, what are these numbers? What are we talking about? And before we get into what
to do with these numbers, I want to emphasize
again, this does not have to do with
fitness level per se. I know some world
class triathletes that have very fast carbon
dioxide blow-off times. That is, their discard rates
are 20 seconds or less. I should also point out that
if you're very stressed, that number is going
to be very small. If you're very relaxed,
like you just woke up after a long night of
sleep and you feel great, that number is going
to be extended. So this is a back of
the envelope measure that you're going
to use each time you decide to do the
exercise I'm going to tell you about in a moment. And the exercise I'm going
to tell you about in a moment can be done every
day if you like. But what the most interesting
studies, at least to me, indicate is that you
could do the exercise I'll tell you about even
just once or twice a week and greatly improve your
efficiency of breathing and shift yourself away from
overbreathing when at rest, even if you're not
thinking about how you're breathing at rest. So what is this exercise? Well, you just got your number,
either low, medium, or high bracket number for carbon
dioxide discard rate. Remember, if you're in the low
category, your number is three. If you're medium,
it's five to six. And if you are in the
long carbon dioxide discard rate, long
duration carbon dioxide discard rate, that
is, 8 to 10 is your number. Now you're going to do two
minutes of what most people would call box breathing. What is box breathing? Box breathing are equal
duration inhale, hold, exhale, hold, repeat. So inhale, hold, exhale, hold. Sounds very easy, right? How long do you inhale and then
hold, exhale and then hold? Well, you now know. If you are in the low group of
carbon dioxide discard rate, your inhale is going to be
three seconds, your hold will be three seconds, your
exhale will be three seconds, and then you repeat,
three seconds. So each side of the
box, if you will, is going to be
three seconds long. If you were in the moderate
carbon dioxide discard rate category, then you're going to
inhale for five to six seconds, hold for five to six,
exhale for five to six, hold for five to six, repeat
for about two minutes. You could do three
minutes if you want. But I think it's important
to have protocols that are feasible for most people. And that's going to mean
doing things for about two to five minutes when it comes
to these breath rehabilitation exercises for restoring
normal breathing. And then, of course, if you are
in the long category of carbon dioxide discard rate, you
should be able to do an 8 to 10 second inhale, 8 to 10 second
hold, 8 to 10 second exhale, 8 to 10 second hold, and repeat. So you could do
that exercise now if you like, or you could
do it at some point offline. You can pause this podcast
if you want and go try it. That's an exercise
that you can do for about two to three minutes
once or twice per week. What's happening when
you do that exercise? Well, first of all,
you are greatly increasing your neuromechanical
control over the diaphragm. This is very important. Most people are not aware
of this phrenic nerve pathway in the diaphragm. And you are greatly increasing
your mechanical control over this pathway
through the process we call neuroplasticity. When you deliberately focus on
a aspect of your nervous system control and particular nervous
system control over musculature that normally is subconscious
and you're not paying attention to and when you actively
take control of that, it requires that your
brain adjust and rewire the relationship between
the different components of that circuit. And the wonderful
thing is that has been shown to lead to changes
in your resting pattern of breathing. Now, why did we go
through the whole business of doing the carbon
dioxide tolerance test? Well, for people who don't
tolerate carbon dioxide very well, they don't have
very good phrenic, that is, neuromechanical
control of the diaphragm, for whatever reason-- again,
it doesn't mean you're not fit. It just means you don't have
or you have not yet developed neuromechanical control
of the diaphragm. It would be near
impossible for you to do box breathing for two
or three minutes with eight seconds in, eight seconds
hold, eight seconds exhale, eight second hold. So that's why we
do a test to see what you're capable of doing. You don't want the box breathing
to be too strained where you're [GRUNTS],, where you're
really challenged to get around the whole box. You want it to be relatively
easy because, remember, you're trying to translate this
pattern to your normal pattern of breathing, that is,
your pattern of breathing when you're not consciously
thinking about breathing. And what are we
really translating when we do this box
breathing type exercise? What you're translating
is the ability to pause between
breaths and yet take full mechanically-driven breaths
that involve the phrenic nerve and diaphragm. So, again, you're
encouraging, especially if you use nasal breathing
when you do the box breathing-- you're encouraging phrenic
control over the diaphragm. And you're getting that six
liters of air per minute or so using fewer and
fewer breaths over time. So this is a, again,
zero cost-- although it does cost a little bit of
time-- zero cost approach to adjusting your normal pattern
of breathing at rest, which has a huge number of
positive outcomes in terms of your ability to stay
relatively calm, to not get the hyperexcitability
of the brain. It has actually been
shown in various studies-- and we'll talk about one
in particular later-- to greatly improve not
just levels of calm and reduce bouts of stress but
also improve nighttime sleep. There are huge
number of benefits that can come from doing
this box breathing exercise. But you got to get the duration
of the size of the box right, and that's why you do the
carbon dioxide tolerance test. One thing that
many people notice after doing the carbon dioxide
tolerance test even just once and then doing this box
breathing exercise once or twice a week is that after
two or three weeks, the box breathing itself
becomes very easy. And in that case, I recommend
taking the carbon dioxide tolerance test over again. And almost always
what you'll find is that you have been
able to extend your carbon dioxide discard rate,
and therefore, you now fall into a different category,
not just the lower medium but the long carbon dioxide
discard rate category, and you are able to extend
the duration of those inhale, hold, exhale, holds
during the box breathing. And, of course, the
ultimate benefit of all this is that it translates to
deeper and yet less frequent breathing when at rest and
when not consciously paying attention to how you're
breathing during the daytime. Again, if at all possible,
do all of this breathing through the nose. For those of you that have
a severely occluded nose, the recommendation always is to
breathe through your nose more. But I do realize
that for some people, it's really uncomfortable
to breathe through the nose because they have such an
occluded nasal pathway. And for you folks, doing
some of this breathing through the mouth
can probably suffice. But if at all possible, do the
breathing through the nose. And please also let me know how
your progress evolves over time with the carbon dioxide discard
rate and the box breathing. And of course, the
positive shifts that occur in normal
unconscious daytime breathing translate to all
the opposite things that we talked about when
you are overbreathing during the daytime. So what I just described in
terms of the carbon dioxide tolerance test and the
exercise using box breathing to restore normal
patterns of breathing and not overbreathe and
therefore not eliminate too much carbon
dioxide is exactly the two tests that were
incorporated into a study that my laboratory
did in collaboration with our associate
chair of psychiatry at Stanford School of Medicine,
Dr. David Spiegel, who's also been a guest on
this podcast previously. And that study
explored box breathing. But it also explored
other forms of breathing and actually compared those
forms of deliberate breathing to meditation as
a means to explore what are going to be the
minimal effective doses and most effective ways to chronically
reduce stress around the clock and improve mood
and improve sleep. So the study I'm referring to
was just published recently. It's entitled "Brief Structured
Respiration Practices Enhance Mood and Reduce
Physiological Arousal." We will also provide a link
to this paper in the show note captions. What this study
really focused on was a simple question, which is,
what is the shortest and most effective practice that
people can use in order to reduce their levels of stress
not just during that breathwork practice or meditation practice
but around the clock, 24 hours a day, including
improvements in sleep? And we were excited to do this
study because many studies had explored how meditation
or, in some cases, fewer studies have
explored how breathwork can impact different brain
states or bodily states. But very few studies had
explored how those breathwork or meditation practices
influenced body-brain states around the clock
when people were not performing the particular
meditation or breathwork practice. The reason we were
able to do this study was really fortunate. The folks over at WHOOP
were generous enough to donate a bunch of
WHOOP straps, which allowed us to measure
heart rate variability, a number of other different
physiological parameters. We also got subjective
reports about people's mood and feelings of well-being. We got data about their
sleep pinged to us from remote locations. So these people, rather than
being brought to the laboratory and being in a very artificial
circumstance, the laboratory, as much as we like to
think our laboratory is realistic-- we
have virtual reality and things like
that-- there's nothing as realistic as the real world. And so we were able
to have more than a hundred subjects out in the real
world living their real lives pinging back to us data all
the time, 24 hours a day so that we could measure how
their different interventions that we asked them to
do, breathwork practices or meditation practices,
were impacting physiological parameters. And they were also
informing us regularly about their subjective
mood, et cetera. We got a lot of data,
as you can imagine. And the basic takeaway
from the study was twofold. First of all, we discovered that
deliberate breathwork practices done for about five
minutes per day across the course
of about a month led to greater reductions in stress
than did a five minute a day meditation practice. Now, that is not to say that
meditation is not useful. In fact, there are dozens,
if not hundreds, of papers, including one
particular, I should say, particularly beautiful
study from Wendy Suzuki's lab at New York University showing
that a daily 10 to 13 minute mindfulness meditation practice
can greatly improve focus, memory, and a number of other
things related to cognition and learning. However, the research
on meditation has shown us that meditation,
at least short meditations, mainly lead to improvements
in focus and memory, not so much reductions in
stress, although they do lead to reductions in stress. What we found was that any
number of different breathwork practices-- and we
explored three-- done for five minutes a
day outperformed meditation in terms of the
ability of breathwork to reduce stress around the
clock compared to meditation. The three types of breathwork
that we explored also showed different effects. I should mention the
three types of breathwork that we compared were
box breathing of the sort that you just learned about. We compare that to something
called cyclic sighing, which involves two inhales
through the nose to get maximally inflated lungs
followed by a long exhale. I'll return to that in a moment. That was repeated
for five minutes at a time for each session. And a third breathwork
practice, which was cyclic hyperventilation,
which, as the name suggests, involves people inhaling
deeply through the nose, then exhaling passively
through the mouth, and then repeating
inhale through the nose, exhale through the
mouth, repeating that for 25 cycles, one cycle
being an inhale and an exhale. So that equals one cycle. Repeating that for 25 cycles,
then exhaling all their air and holding their
breath with lungs empty for about
15 to 30 seconds, and then repeating inhale,
exhale, cyclic hyperventilation for the duration
of five minutes. So people were divided into
these different groups, either mindfulness
meditation where they sat, they were not told to
control their breathing in any specific way. They closed their eyes. They focused their
attention on a region just behind their forehead. One group did that. The other group
did cyclic sighing. Another group did box breathing. Another group did
cyclic hyperventilation. As any sort of clinical
trial like this ought to, we then swapped people
into different groups. So they served as
their own control. So we could evaluate
any between and within individual variability. Again, there are a lot
of data in this paper. But the takeaway was that for
the sake of stress reduction around the clock and for
the sake of improving sleep and mood, the most
effective practice of the four practices
that we examined was the cyclic sighing. Again, cyclic sighing is
performed the following way. You inhale through the
nose as deeply as you can. Then you do a second inhale
immediately afterwards to try and maximally inflate the lungs. In fact, that's what happens. We know that during
that second inhale, even if it's just a very
sharp, short inhale, the extra physical
vigor that's required to generate that
second inhale causes those alveoli of the lungs,
which may have collapsed-- and, indeed, in between
breaths and often even just through the course of
the day and especially if we get stressed, those
alveoli of the lungs start to collapse. And because they're
damp on the inside-- they have a little bit of fluid. They're like a balloon
with a little bit of fluid in the middle. It takes a little
bit of physical force to pop those open. Now, you're not literally
exploding them pop. But you're reinflating
them with air. And then you perform the
long exhale through the mouth until lungs are empty. So it looks exactly like this. [INHALES DEEPLY] [INHALES SHARPLY] [EXHALES] Now, we know that one
single physiological sigh of the sort that
I just described performed at any time of
day under any conditions, whether or not you're about to
walk on stage to give a talk or you're in a meeting and
you're feeling stressed, or you're in a conversation
that's very stressful, or you can feel stress mounting
because you're in traffic or any number of psychological
or physical stressors that may be approaching
you or you feel are oppressing you, doing one
physiological sigh of the sort that I just described is
the fastest physiologically verified way that we
are aware of to reduce your levels of stress and to
reintroduce calm, that is, to shift your autonomic
nervous system from a state of heightened
levels of autonomic arousal. That is, sympathetic nervous
system as, it's called, is at a higher activation
level than the so-called parasympathetic nervous system. Again, sympathetic nervous
system having nothing to do with sympathy,
has everything to do with so-called
fight or flight, although it controls
other things, too, including positive arousal. And the parasympathetic
nervous system, often referred to as the
rest and digest system, although it does
other things, too, is associated with calming. Those two things
are always in kind of push-pull with one another,
like a seesaw or push-pull, however you want
to think about it. One physiological sigh,
meaning that big, deep inhale, short second inhale
also through the nose, and then long exhale to
completely lungs empty, is known to restore
the level of balance in the
sympathetic-parasympathetic neural circuitry and
is the fastest way to reintroduce calm. That's one physiological sigh. In this study, what we
asked was that people perform that repeatedly,
so-called cyclic sighing, for the duration
of five minutes. And the people who did
that cyclic sighing for five minutes a day,
regardless of the time of day that they did it, experienced
the greatest reductions in stress not just
during the practice but around the 24-hour cycle. And it translated,
again, to all sorts of positive subjective changes--
improvements in sleep, lower resting heart rate
at all times of day. So this is important. Again, this study was
not just exploring what happens during
meditation or breathwork, cyclic sighing, et cetera. It was exploring how the changes
that occur during that practice translate to
changes in breathing and heart rate, mood, et cetera,
throughout the 24-hour cycle. So the takeaway here is twofold. First of all, if
you are somebody who wants to improve
your mood and reduce your overall levels
of stress and you only have five minutes a
day to invest in that, hopefully you're doing
all the other things like trying to get proper
sleep and exercise, social connection, nutrition,
et cetera, sunlight in the morning, of course. Can't leave that out. But if you were going to
devote five minutes a day to a stress reduction
practice that is now supported by data to translate
to reductions in stress around the clock,
the data say that you would want to invest that
in cyclic sighing, that is, double inhale through
the nose, extended exhale through the mouth until
your lungs are empty, then repeat for
five minutes a day. You, of course, if you
like, could do meditation. It still had positive
effects, meaning it reduced stress, although
not as much as cyclic sighing. You could do box
breathing if you want for the purpose
of reducing stress. All the practices we
explored did reduce stress. But cyclic sighing performed
for five minutes a day had the most robust
and pervasive effect in reducing stress, improving
mood, and improving sleep. That's the first
message of the study. The second takeaway is that
one physiological sigh-- that's right just one
physiological sigh, where you inhale deeply
through the nose another inhale through the
nose to maximally inflate the alveoli of the
lungs, and then you exhale to completely lungs
empty and then go back to normal breathing,
is the fastest way to introduce a level
of calm and to reduce your overall levels of
stress in real time. And this is very important. I think that out
there these days, we hear a lot about stress
reduction techniques. And most all of the stress
reduction techniques that have been
explored, everything from massage to meditation
to breathwork to a hot shower to a foot rub,
will calm you down. The question is, do
they calm you down just during that practice? Great if it does. But does it also translate
to reduced levels of stress at other times
in the 24-hour cycle and other positive
effects as well? So one physiological sigh
is a very efficient way to adjust that ratio of
sympathetic to parasympathetic activation and immediately
bring about calm. So it's excellent for
real-time control of stress. The other thing about
physiological sighs is that it's not a hack. It's not the application of a
breathing practice to something that it wasn't intended for. In fact, physiological
sighs were not discovered by me at all. They were discovered
by physiologists in the 1930s, who found that
when people underbreathe, they have a buildup of carbon
dioxide in their system. And even though carbon
dioxide is essential for life, you don't want too much
of it in your system. And that people, whether or
not they were asleep or awake, would engage a physiological
sigh spontaneously, subconsciously. They would do this double
inhale through the nose and extended exhale
through the mouth. And that did not just eliminate
excessive carbon dioxide from the system. It also rebalanced the
oxygen-carbon dioxide ratio in the proper ways. In fact, it's
observed in animals. You might see this in
animals that are tired. When animals or
humans get tired, they tend to start
underbreathing a little bit, and that can often disrupt
the balance of carbon dioxide and oxygen. And right
before a dog will go down for a nap, for instance,
you'll notice that it'll do this double inhale, exhale. people when they are sleeping,
if they hold their breath for a period of time,
which, frankly, all of us do periodically
throughout sleep, they will engage a spontaneous
physiological sigh. During the daytime, we are often
holding our breath, especially nowadays-- and there's
a study on this that we'll talk about a
little bit later-- where when people text message
or they're emailing, although nowadays people are
mainly on social media and text messaging, they often
are holding their breath. They will follow a breath
hold by a physiological sigh because during that
breath hold, they're building up the level of
carbon dioxide in their system. Now, mind you, I spent
close to a half an hour telling you that most people
are overbreathing at rest, and that's also true. But people often will
shift from overbreathing to underbreathing, which
is a terrible pattern. So physiological sighs done
either as a one-off, one physiological sigh to clamp
stress or reduce stress in real time, or repeatedly
over five minutes as a practice that you do each day is
going to be not just the most effective way to
approach reducing stress around the clock and in real
time but also the one that's highly compatible with the
way that the neural circuits that control breathing
were designed. The physiological sigh has some
other very useful applications. One of the more, I would say,
useful ones, at least to those of you that exercise,
is going to be the use of physiological
sigh in order to remove the
so-called side stitch. So if you've ever been running
or swimming or exercising and you felt a cramp
on your right side, chances are, despite what your
high school PE coach told you, that raising your
arms above your head or drinking less water
before you exercise is not going to get
rid of that cramp. And here's why. It's not a cramp at all. If you recall the cervical
3, 4, and 5 nerves that give rise to the phrenic nerve
and go down and innervate your diaphragm, well,
as I mentioned before, a certain number of
those nerve fibers actually course into the
diaphragm and go up underneath. And if you recall
earlier, I also said that the diaphragm sits
right on top of the liver. In other words, you actually
have a sensory innervation of the diaphragm, the deep
diaphragm, and the liver. And there's something called
referenced pain, which is what people
generally experience when they have that side stitch
on their right-hand side. So if you're ever
exercising and you feel a cramp on your
right-hand side, it's possible that
it's a genuine cramp. But more likely is the fact
that that phrenic nerve sensory innervation is now
being carried up to your brain and you are detecting some local
or referenced pain in the liver and in the diaphragm. Now, that doesn't
necessarily mean you're doing anything wrong,
although you might not be breathing properly for
running at that moment, and that's what gave rise to it. It could be some spasming
of the phrenic nerve or some inefficient
breathing during running. We had an entire series on
fitness with Dr. Andy Galpin. One of those episodes
included a lot of information on breathing. It was the episode on
endurance, although breathing was a topic that was thread
through multiple episodes in that series. You can find that series
at HubermanLab.com. Talks a lot about how to
breathe during running, how to breathe during
weightlifting, et cetera. But the point for now
is that if ever you're experiencing that
right-side side stitch, I encourage you to perform
the physiological sigh. And the good news is you can
perform it while still running or while still
swimming, although I suppose with swimming,
you might have to make some adjustments
because, of course, you don't want to inhale
water, or while cycling or any type of activity. If you perform that
physiological sigh generally two or three times,
what will occur is that because of
changes in the firing of the phrenic nerve, and in
particular because of changes in the sensory feedback
from the sensory component of the phrenic nerve
back to the brain, you will experience an
alleviation of the pain from that right-side
side stitch. In other words, you can
get rid of side cramps doing physiological
sighs during activities, in particular during
running activities. Now, I should also mention that
if you're experiencing a side stitch on the
left-side, chances are that has to do with excessive
air or fluid in your stomach. And there are
reasons for that that also have to do with the way
that the phrenic nerve is-- it's bilateral and
branches to both sides and is catching sensory input
on the left side from some of the local organs and sensory
innervation of those organs. But if you have
right-side side stitch, the physiological
sigh done two or three times while still running ought
to relieve that side stitch. Now, as long as we're
talking about breathing and the phrenic nerve
and the relationship between the phrenic nerve and
your liver and your stomach and some of the other
organs in that neighborhood, we should talk about the
relationship between breathing and heart rate. This is an incredibly
important topic, so much so that I perhaps
should have brought it up at the beginning of the episode. But nonetheless, you now know
what your diaphragm does. When you inhale, your
diaphragm moves down. That's right. When you contract your
diaphragm, it moves down. It creates space for
your lungs to inhale. And when you exhale,
your diaphragm moves up. Well, when you inhale and
your diaphragm moves down, what happens is there's
more space created in the thoracic cavity and
particularly if you're also breathing deeply and you're
using those intercostal muscles to expand your ribs. As a consequence,
the heart actually gets a little bit bigger. It's a temporary
enlargement in the heart. But it's a real enlargement. And as a consequence,
whatever blood is in the heart is now in a larger volume
because the heart got bigger. And as a consequence, that
blood is moving more slowly through that larger volume
for a short period of time. But nonetheless, it's
moving more slowly. Your nervous system detects
that and sends a neural signal to the heart to speed
the heart rate up. In other words, inhales
increase heart rate. The opposite is true
when you exhale. When you exhale, your
diaphragm moves up. Your rib cage tends
to move inward a bit. And you compact the heart. You reduce the volume
of the heart overall. When you reduce the volume
of the heart overall, blood flow through
the heart accelerates because it's a smaller volume. So a given unit
of blood is going to move more quickly
through that small volume. Your nervous system detects
that and sends a signal to slow the heart down. So just as inhales
speed the heart up, exhales slow your
heart rate down. Now, of course, even though
you can double up on inhales or even triple up on inhales,
sooner or later, if you inhale, you're going to have to exhale. And the converse is
also true, of course. So what does this mean in terms
of controlling your heart rate? Well, let's say you are
going in for a blood draw, or you're going out on
stage and you're stressed. Well, I would encourage you to
do a physiological sigh, maybe two physiological sighs to
bring your level of calm up and your level of stress down. Nonetheless, if
you have any reason why you want to quickly
reduce your heart rate or accelerate your heart rate
for sake of physical work output or to calm yourself
down additionally, not just use the physiological
sigh, well, then you can take advantage of this
relationship between inhales and exhales
controlling heart rate. If you want to increase
your heart rate, you can simply inhale
longer and more vigorously relative to your exhales. And if you want to
decrease your heart rate, well, then you're going to
make your exhales longer and/or more vigorous
than your inhales. In fact, this process, which
is called respiratory sinus arrhythmia, is the basis of what
we call heart rate variability. Heart rate variability
involves the vagus nerve, the 10th cranial nerve, which
is a parasympathetic nerve that is associated with
a calming aspect of the autonomic nervous system,
slowing your heart rate down by extending your exhales. And it really forms the basis
of most all breathing practices. If you look at any
breathing practices, whether or not it's Wim Hof
breathing, Tummo breathing, Kundalini breathing,
Pranayama breathing, physiological sighing, cyclic
sighing, and on and on and on, if you were to measure the
ratio of inhales to exhales and the vigor of inhales to
exhales, what you would find is that each one would create a
net increase or a net decrease in heart rate that could be very
accurately predicted by whether or not that breathing practice
emphasized inhales, emphasized exhales, or had those two
features, inhale and exhale, be of equal duration
and intensity. In fact, if you wanted to
equilibrate your heart rate, what you would do is you
would do box breathing because inhale,
hold, exhale, hold is, by definition, creating
equal duration inhales and exhales of essentially
equivalent vigor. When you do a
physiological sigh, you're doing two
big inhales, which is going the speed
your heart rate up just a little bit, but then
a long extended exhale. The exhale in the end is much
longer than the two inhales even when combined. And so you get a net decrease in
heart rate, the calming effect. And then practices such as Tummo
breathing or Wim Hof breathing or cyclic hyperventilation,
[HYPERVENTILATES] deep inhales and exhales, the inhales
are more vigorous compared to the more passive
exhales-- are going to lead to
increases in heart rate. So the relationship between
breathing and heart rate is an absolutely lockstep
one where your heart rate follows your breathing. Your heart rate
and your breathing are in an intimate
discussion with one another, but where always and
forever your inhales increase your heart rate,
your exhales decrease it. Now, this feature,
which physicians call respiratory
sinus arrhythmia, or we sometimes hear about more
often nowadays as heart rate variability, is something
that people in sport have known about for
a very long time. It's why, for instance, that
marksmen will exhale just prior to taking a shot. That's particularly
true for people that compete in the biathlon,
where they cross country ski. So their heart rate
is up, up, up, up, up. Then they'll get to the
point where they actually have to shoot a target,
and they'll exhale, and then they'll
shoot the target. This is also why, for instance,
if you want to bring your heart rate down very quickly between
rounds of martial arts, there are a number of
different ways to do that. But an extended exhale of any
kind or, frankly, any breathing practice that emphasizes
exhales is going to bring your heart rate down. This has been incorporated in
a number of different contexts, including sport, military. It's also now being incorporated
in a clinical context for people who feel a
panic attack coming on. I'm very gratified to learn that
the physiological sigh is now being explored as a tool
to prevent panic attacks and anxiety attacks. This is prior to the
panic attack, people bringing their heart
rate down, again, through those extended exhales. So learning to
extend your exhale is really a terrific
skill to master, and it's a very easy
skill to master, frankly. Why do I say a skill? Well, remember what
I said earlier, which is that humans
inhale actively and most typically
will passively exhale, just let the air [EXHALES] drop
out of them at whatever rate, depending on how much
air they inhaled. Actively exhaling, that is,
actively relaxing the diaphragm and actively relaxing
those intercostal muscles of the chest, those ones
that are, I should say, between the ribs,
is a skill that you can very quickly
acquire and will allow you to use
that relationship between the phrenic nerve,
the diaphragm, and the size of the heart, the heart
volume, and all that stuff to really take control
of heart rate quickly. So that if you feel like your
heart is racing too much-- and, frankly, a
lot of people have a lot of what's called
interoceptive awareness, especially anxious people. They can really
sense what's going on in their body, other
people less so. Like, oh my god,
my heart's beating. It's ready to jump out of my
chest, and I don't like that. I don't like that. [EXHALES] Big, long exhale. It doesn't matter if you do it
through the nose or the mouth. Big, long exhale is
going to allow you to slow your heart rate down. Let's talk about hiccups. Everybody experiences
hiccups from time to time. I think most people would
agree that one hiccup is sort of funny. Two hiccups in a
row is really funny. And three hiccups
in a row is where it starts to be concerning,
in part because hiccups can be kind of painful. You can experience pain in
your gut or your lower abdomen and sometimes in
your chest as well. And it feels kind of intrusive. It gets in the way of
having conversation or just sitting there and relaxing. Fortunately, there's a simple
way to get rid of hiccups. And you can arrive at
that simple technique if you understand a
little bit about what gives rise to hiccups. The reason we get
hiccups at all is because we experience a
spasm of the phrenic nerve. The phrenic nerve,
as you recall, is a nerve that emanates
from the cervical region, to be specific C3, 4, and 5. Those spinal nerves go down,
of course, behind the heart and innervate the
diaphragm, which is the muscle that when it
contracts, it moves down and allows the lungs to fill. And then when you
relax the diaphragm, then the diaphragm moves
up, and the lungs shrink or they expel air,
so-called exhalation. Now, the phrenic nerve also
has that sensory branch. So it's not just involved
in controlling the diaphragm at the motor level. It's also sensing things
deep within the diaphragm and in the liver as well
because the liver sits right below the diaphragm. So a hiccup has that
painful sensation from time to time because there's
a rapid sensory feedback or a signal, rather, of a
sharp sensation of contraction within the diaphragm. And that's relayed
back to the brain. And you consciously perceive
that as a little bit of pain. And then, of course, the
hiccup is [HICCUPS] the hiccup, which is the spasming
of the phrenic nerve that you experience more
or less in your throat. But all this really is happening
along the phrenic nerve and toward the diaphragm. What this all means
is that if you can stop the phrenic nerve from
spasming, you can stop hiccups. There are a lot of
approaches that people have tried to take to eliminate
spasming of the phrenic nerve. You'll hear that breathing
into a bag, which is one way to reingest or
reinhale carbon dioxide that otherwise would be expelled out
into the environment, can help. That's a very indirect method. It rarely works, frankly,
because it really has to do more with
adjusting your breathing to try and adjust the
activity of the phrenic nerve. It's a really roundabout way
of trying to alleviate hiccups. Some people will
experience relief from drinking from
a glass of water from the opposite
side of the glass. So you have to tilt
over at the waist. It's a kind of messy approach. Again, it doesn't tend to
work a lot of the time. For some people, it
works every time. But for most people,
it doesn't work at all. However, there is
a technique that can reliably eliminate hiccups. And it's a technique that takes
advantage of hypercontracting the phrenic nerve over
a short period of time so that it then subsequently
relaxes or alleviates the spasming of
the phrenic nerve. And that simple method is to
inhale three times in a row. This is a very unusual
pattern of breathing. But what it involves is
taking a big, deep inhale through your nose. Then before you exhale any
air, take a second inhale through the nose, however
brief that inhale might be, and then a third even micro
or millisecond long inhale through your nose to
get that third inhale. And then hold your breath
for about 15 to 20 seconds, and then slowly exhale. So even though I'm not
experiencing any hiccups right now. I will demonstrate the method
for eliminating hiccups so that you're all
clear on how to do it. OK, here I go. [INHALES DEEPLY] [INHALES] [INHALES] [EXHALES] OK, so it's three inhales
all through the nose. And it is true that that
second and third inhale takes some physical
effort to really get additional air into the
lungs without exhaling first. It feels like-- the only
way I can describe it really is as a sharp second
and third inhale because you really
have to engage the musculature of those
intercostal muscles and the diaphragm
in order to do it. And then that long exhale can be
through the nose or the mouth. But I find it particularly
relaxing or even pleasant to do it through the nose. This method of three inhales
through the nose followed by a long exhale through
the nose or mouth will eliminate hiccups right
away because what it does is it hyperexcites the
phrenic nerve three times in a row, a very unnatural
pattern for the phrenic nerve to fire. And then it undergoes
a hyperpolarization, as we call it, in which
the phrenic nerve actually stands a much lower probability
of getting activated again for some period of
time afterwards. So it is important
that you try and return to normal cadence of breathing
after doing this three inhales followed by a long exhale. If you need to perform
it a second time in order to eliminate hiccups because
they're simply not going away, that's fine. You can do that. But as far as we
know, this is the most efficient and science-supported
way to eliminate hiccups. Now, up until now
I've been talking about breathing techniques,
and I've mainly focused on breathing techniques
that emphasize the exhale, whether or not it's the
carbon dioxide tolerance test, whether or not
it's cyclic sighing or the physiological sigh
that you use in real time to reduce stress. One thing that we haven't
talked about so much is cyclic hyperventilation. Cyclic hyperventilation,
as you recall, is a bout of 25 or
so breaths inhaling deeply through the nose and then
passively exhaling or sometimes actively exhaling,
typically through the mouth. So it might look like this. [HYPERVENTILATES] That's a very
active inhale through the nose and exhale through the mouth. It can also be
done active inhale through the nose, passive exhale
through the mouth, like so. [HYPERVENTILATING] In any event, that pattern
of breathing repeated for 10 to 25 breaths
greatly increases levels of autonomic arousal. In fact, it's known to deploy
adrenaline from the adrenals. And in our study, we had people
then expel all their air, so breathe out, hold their
breath for 15 to 30 seconds, and then repeat for a
period of five minutes. That did lead to some very
interesting and positive physiological changes in
terms of stress mitigation, although not as
significant as was observed with cyclic sighing,
as I talked about earlier. Now, there is a lot of interest
in cyclic hyperventilation for sake of, for instance,
extending breath holds. This has become popular in part
because of the so-called Wim Hof method, which
is a method that combines breathing,
cyclic hyperventilation, followed by lungs full or
lungs empty breath holds, depending on which variant
of the Wim Hof method one is using. Separately-- and I really
want to emphasize separately-- the Wim Hof method also
involves deliberate cold exposure, which, as all
of you know, I'm a big fan of and we've done episodes
of this podcast on. And we have toolkits on
deliberate cold exposure for increasing dopamine
levels, epinephrine levels, immune system
function, et cetera. Wim Hof method also
incorporates that. And it has a
mindfulness component. I do want to caution
people that any time you're doing cyclic
hyperventilation, you want to be very cautious about
not doing it in or near water because it does greatly increase
the risk of shallow water blackout. And that's because when you
do cyclic hyperventilation, you are expelling, you're
exhaling more carbon dioxide than usual. And what I haven't told you yet
is that the trigger to breathe is actually an increase
in carbon dioxide. What I mean by that is
you have a small set of neurons in your
brainstem that can detect when carbon dioxide
levels in your bloodstream reach a certain level. And when they reach that level,
they trigger the gasp reflex and/or the hunger for breathing. In other words, we don't
breathe because we crave oxygen, although we do need oxygen,
of course, in order to survive and for our brain to function
and our bodily organs to function. But our brain is wired such that
it has a threat sensor, which is carbon dioxide levels
are getting too high, and that's what triggers
the motor reflex to breathe and to, in some
cases, gasp for air, depending on how
starved for air we are. So if you do cyclic
hyperventilation, whether or not
it's Wim Hof method or whether or not
it's Tummo method-- again, these things are similar. They're not exactly the same. There are other
breathing methods that incorporate cyclic
hyperventilation. What you're doing
is you're getting rid of a lot of carbon
dioxide, and therefore, you're removing the impulse
or lowering the impulse to breathe so that when you
enter that breath hold phase after the hyperventilation, it's
a much longer period of time before you feel the
anxiety and the hunger and the impulse to breathe. That's one of the real
benefits of any technique that incorporates cyclic
hyperventilation, is that rather than reduce
your stress level in real time, it actually does the opposite. It increases your stress level. It increases your levels
of autonomic arousal. But you're doing
it deliberately. And then during those breath
holds, what's happening is you have a lot of
adrenaline circulating in your system
because of the way that hyperventilation triggers
the release of adrenaline from your adrenal glands. It also triggers the
release of epinephrine, which is the same as
adrenaline, from a little brain area called locus
coeruleus, which makes you feel more alert. And then during
those breath holds and in the subsequent rounds
of cyclic hyperventilation, people experience what it is
to have a lot of adrenaline in their system. But they are
controlling the release of that adrenaline, which is
far and away different than when life events are triggering
that adrenaline. So what it really is is a
form of self-induced stress inoculation. And I do think
there are benefits to practicing cyclic
hyperventilation because it does allow you to learn how
to self-deploy adrenaline and epinephrine
from locus coeruleus and from the adrenals. Or I got that
backwards-- adrenaline from your adrenals
and epinephrine from locus coeruleus. And it allows you
to explore what it is to maintain calm
state of mind and body when you have a
lot of adrenaline in your system, which
certain studies are starting to show can allow people
to be able to lean into the stressful
aspects of life. And let's be honest, life
is stressful in any event. And we're all going
to experience stress at some point or another. And when we do, we
want to make sure that we're not overtaken by
the release of adrenaline from the adrenals, that
sudden surge of epinephrine from locus coeruleus. So doing cyclic hyperventilation
maybe one or two times per week-- again,
25 breaths, active inhale, passive or active exhale. Do expect to feel tingly because
of that reduction in carbon dioxide from exhaling so much. Do expect to feel a
little bit agitated. Be very careful
doing this if you're somebody who has anxiety
attacks or somebody who has panic attacks or
disorders of any kind. But if you don't and you
want to explore this, you'll notice you start
to feel really ramped up. And then during
the breath holds, which, again, can be done
by exhaling and stopping for some period of time,
15, maybe even 60 seconds, is a time in which
you can explore how to remain mentally calm. Some people even choose
to do math problems or think of things in a
kind of structured way while they have a lot of these
hormone neurotransmitters circulating at high levels in
their system, in other words, as a way to learn to manage your
mind and body under conditions of stress. Now, if you are somebody who's
using deliberate cold exposure, either cold showers or ice
baths or cold immersion, I often get asked
how best to breathe during those different
types of activities. Really, there's no
best way to breathe. Although if you wanted
to turn those activities into their own form
of stress inoculation, again, please don't use
cyclic hyperventilation. That's dangerous. I don't recommend it whatsoever. But you can try to actively
slow your breathing, that is, to make sure that you're
engaging in rhythmic breathing. Now, up until now I've said
that rhythmic breathing is the default.
Pre-Botzinger nucleus controlling rhythmic
breathing is the default and that doubling up
on inhales and exhales is something that happens when
you deliberately take over the action of
pre-Botzinger complex. Now, that's true
99% of the time. However, there are
certain conditions, such as conditions of heightened
state of emotional arousal-- if you think about
somebody who's been crying, oftentimes they'll
do the double inhale, exhale [INHALES SHAKILY]
or triple inhales. Or if somebody is very, very
afraid, it's all inhales. So it does sometimes
happen spontaneously. Actually, when we get
into very cold water, there's a very robust
decrease in the activation of the prefrontal
cortex, which is the area of brain real estate
right behind the forehead that controls structured
thinking, your ability to reason and make sense
of what's going on. If you get into
really cold water, you should not expect that
brain region to work or at least not work very well at all for
the first 20 or 30 seconds that you're in the cold water. From the time you
get into cold water, because here we're talking
about deliberate cold exposure, I encourage you to try
and control your breathing and make it rhythmic, that is,
inhales follow exhales follow inhales follow
exhales, even if they have to be fast inhale
exhale, inhale, exhale. Why? Because the default when we get
into a stressful circumstance, emotionally or physically
stressful circumstance, is that rhythmic breathing stops
and that parafacial nucleus takes over and it's
[INHALES RAPIDLY],, and it's that kind
of panicky mode. And by simply controlling
our breath, again, even if it's fast
from inhale to exhale and making sure that we're
alternating inhales and exhales rhythmically-- and
what you'll find is that you'll be
able to navigate that what would otherwise be
a very stressful circumstance and make it less stressful
or maybe even pleasant. And that skill
definitely translates to other aspects
of life in which you're hit square in the face
with something stressful. You'll notice your breathing
and your pattern of breathing switching to multiple
inhales or breath holding, essentially departing
from rhythmic breathing. And by quickly returning
to rhythmic breathing and maybe even trying
to slow the breathing and extend those exhales,
you'll find that you can very quickly calm down. Next, I'd like to discuss what
I find to be an absolutely fascinating topic. It's also one that's highly
useful in the world, which is how your specific
patterns of breathing relate to your ability to learn
and to remember information, how it can modulate fear,
and a number of other aspects of how your brain functions. This is a literature that's
been reviewed recently in a lot of exquisite
detail in a beautiful review by Jack Feldman, who
I mentioned earlier, one of the pioneers of the
neuroscience of breathing. The title of the review is
"Breathing Rhythm and Pattern and Their Influence on Emotion." Again we'll, provide a link
to this review in the show note captions. This review includes discussion
of several studies, one in particular that I'll get
into in a bit of detail, that describes the following. Right now, I just want
you to breathe regularly, meaning rhythmically. You can inhale and
exhale through your mouth or through your nose. I'd prefer that you do
it through your nose because nasal
breathing, unless you need to breathe through your
mouth because of hard exercise or eating or talking,
is always going to be the better way to go. Nasal breathing improves
the aesthetic of your face. That's been shown. We'll talk about that just
briefly in a few minutes. Nasal breathing
improves the amount of oxygen you can
bring into your system, et cetera, et cetera. OK, so just breathe. Inhale, exhale, inhale, exhale. And know that
during your exhales, your pupil, that is, the pupil
of your eye, is getting bigger. And as you exhale,
it's getting smaller. In addition, when you inhale,
your reaction time to anything that happens around you-- a
car swerving in front of you, something that you might detect
in the periphery of your vision or hear off in the distance-- increases significantly compared
to when you're exhaling. In addition, when
you are inhaling, your ability to remember
things, especially things that take a bit
of effort to remember, and your ability to
learn new information is significantly greater than
it is when you're exhaling. Now, as you hear all that,
you're probably thinking, OK, how do I just inhale? Well, of course, that's not
going to be the best approach. You need to exhale as well
for all the reasons you now are well aware of. But what these findings
really illustrate-- and I should mention
these findings are all carried out in humans. So these relate to some
stuff in animal studies. But what I just described has
been shown in human studies consistently. When we inhale
and, in particular, when we inhale through
our nose, our brain is not functioning in the
same way as when we exhale. Now, that doesn't
mean that our brain is functioning in a
deficient way when we exhale. It just doesn't function
as well as it relates to memory retrieval,
memory formation, and some other
aspects of cognition. Now, you might be asking, why
in the world would this be? Well, I wasn't consulted
at the design phase, and anyone that tells
you that they were you should back away from quickly. But one reasonable explanation
for why our brain functions better, at least in the context
of what I just talked about, when we inhale is because the
olfactory system is actually the most ancient sensory system
of all the sensory systems we have. So before vision, before
audition, before touch, before all of that,
the olfactory system is the most ancient system. And the olfactory
system, of course, is designed to detect
chemicals in the environment. And so if you imagine
an early organism that perhaps we evolved
from or perhaps we didn't but nonetheless
that we share some features of, at least in
terms of olfactory function, in order to get that chemical
information into the brain, you need to inhale. You need to bring
that information in. Now, for aquatic animals, they
could take it in through water. But for animals that are
terrestrial that live on land, they would have to get
it through the air. So inhalation, we know,
activates certain regions of the so-called
piriformis cortex. These are areas of the
neocortex that are more ancient, as well as increasing
the activity of brain areas such as the hippocampus,
which is a brain area involved in learning and memory. In fact, one of the studies
that illustrates this most beautifully is a study
that was published in The Journal of
Neuroscience in 2016. By the way, Journal
of Neuroscience is a very fine journal. And the title of this paper
is "Nasal Respiration Entrains Human Limbic Oscillations and
Modulates Cognitive Function." This is a paper that followed
up on an earlier paper that showed that when people
breathe in through their nose, their recognition and
their discrimination of different odors was far
greater than when they breathe in through their mouth. Now, that result
was interesting, but it was also sort of a
duh because you smell things with your nose, not your mouth. You taste things
with your mouth, and you speak with
your mouth, and there are bunch of other things
you can do with your mouth. But nonetheless, that
study pointed to the idea that the brain is different
during nasal inhalations versus nasal
exhalations versus mouth inhalations versus exhalations. What it basically showed
is that the brain ramps up its levels of activity,
and that signal to noise that we talked about
earlier, if you recall, that ability for the
brain to detect things in the environment, is
increased during inhalations. But because that earlier study
focused on smell, on olfaction, there was a bit of
a confound there. It was hard to separate
out the variables. So this paper, the one I just
mentioned, "Nasal Respiration Entrains Human and Limbic
Oscillations and Modulates Cognitive Function," did not
look at detection of odors. Rather, it looked at things
like reaction time or fear. And basically, what it found is
that reaction time is greatly reduced when people
are inhaling. So they had people look
at fearful stimuli. They looked at their reaction
time to fearful stimuli, in other words, their
ability to detect certain kinds of stimuli. And they were given a lot of
different kinds of stimuli. So they had to be able to
discriminate between one sort of-- oops, excuse me. By the way, folks,
for those listening, I just bumped the microphone,
getting rather animated here. What the subjects
had to do was detect one type of stimulus
versus another stimulus that they were being exposed to. And what they found is
if people were inhaling as that fear-inducing stimulus
was presented, their reaction time to notice it was
much, much faster. And they related that to
patterns of brain activity, and they were able to do that
because they were actually recording from
the brain directly from beneath the skull. And they were able to
do that because they had some patients that had
intracranial electrodes embedded in their brain
for sake of trying to detect epileptic seizures. So there's a lot to
this study and a lot that we could discuss. But the basic takeaway is
that when people are inhaling, that is, when
they're drawing air in through their
nose in particular, their ability to
detect what's going on in the world
around them is greatly enhanced and not just
for fear but also for surprise of all sorts. So when people are
inhaling, their ability to detect novel stimuli,
things that are unexpected or that are unusual
in their environment, is significantly increased. Again, we'll put a link
to this study as well. I find it to be one of the
more interesting studies in this realm, although there
are now many additional studies that support this
statement that I made earlier, which is
that during inhalation, also called
inspiration, there are a number of very fast
physiological changes, such as changes
in pupil diameter, changes in the activity
of the hippocampus, this memory encoding and
retrieval area of the brain, and other areas of the brain. So what's the tool
takeaway from this? If you are sitting down to read
or research or study or you really want to learn
some information-- maybe you're listening to a
podcast or some other sorts of information that
you want to retain-- it actually makes
sense to increase the duration or the intensity
of your inhales as you do that. The more that you're inhaling
relative to exhaling in terms of duration, the more that
your brain is in this focused mode and this mode of being
able to access and retrieve information better. Now, there's one
caveat to this that I think is important because
I know a number of people listen to this podcast
for sake of gleaning tools not just for
cognitive enhancement but for physical enhancement. It turns out that when
you are inhaling air, you're actually less
able or, I should say, less efficient at generating
voluntary movements. Now, that might
come as a surprise. Up until now, we've basically
been talking about inhalation is great, almost to the
point where you wonder like, is the exhalation
good for anything? You don't want to overbreathe
and kick out too much carbon dioxide. Well, of course exhalation
is great for things. In fact, if you're somebody
that's played baseball or softball, what are you told? That you should
exhale on the swing to generate the maximum
amount of power. If you're somebody who has
done martial arts of any kind, was traditional Western
boxing, as you strike, that's where people
typically do the hiya, laying the sort of
classic karate type thing. That's more of a movie thing. I don't know whether or not
people actually use the hiya. But in boxing, oftentimes people
will do [EXHALES SHARPLY].. They'll do a rapid exhalation,
a forceful exhalation, keeping in mind, again, that
inhales typically are active. They engage the
diaphragmatic muscle. They engage those
intercostal muscles. Whereas exhales
tend to be passive unless we take active
control of the exhale. And, indeed, our
ability to generate fast, directed, so-called
volitional, voluntary movements is greatly enhanced if we do
them during the exhale, not the inhale. Now, with all of that
said, I haven't yet really talked about mouth
versus nasal breathing. And it really can be a
fairly short discussion because what abundant data now
show and has been beautifully described in the book called
Jaws, A Hidden Epidemic-- this is a book that was written
by Paul Ehrlich and Sandra Kahn, my colleagues at
Stanford School of Medicine. It has an introduction and a
foreword from Jared Diamond and from the great
Robert Sapolsky. So some real heavy
hitters on this book. What that book
really describes is that whenever possible,
meaning unless you're speaking or eating or you're
exercising or other activities require some change in
your pattern of breathing, we should really all be striving
to breathe through our nose, not through our mouth. And that relates
to the increased resistance to breathing
through the nose we talked about earlier. Again, I'll say it a third
time, that increased resistance through the nose allows you to
inflate your lungs more, not less. The other thing that
breathing through your nose allows you to do is it both
warms and moisturizes the air that you bring into
your lungs, which is more favorable
for lung health than breathing
through the mouth. Hard breathing through
the mouth or simply mouth breathing at all is
actually quite damaging or can be, I should
say, quite damaging to some of the respiratory
functions of your lungs. That, of course, does not mean
that you shouldn't breathe hard through your mouth when
you're running or sprinting or exercising hard. But you don't want
mouth breathing to be the chronic default
pattern that you follow. Nasal breathing is
the best pattern of breathing to follow
as a default state. Another aspect of
nasal breathing that's really beneficial is
that the gas nitric oxide is actually created
in the nasal passages. It's a gas that can
cause relaxation of the smooth muscles that
relate to the vasculature not just of your nose
but of your brain and for all the
tissues of your body. This is why nasal breathing
and not mouth breathing is great for when you want
to relieve congestion. So a lot of these things
seem counterintuitive. Your nose is stuffed. So that mainly makes people
breathe through their mouth. But it turns out that
breathing through your nose will allow some dilation of the
vasculature, more blood flow, dilation of the nasal passages,
and delivery of nitric oxide to all the tissues of your body. And that dilation of
the small capillaries that innervate essentially
every organ of your body allow the delivery
of more nutrients and the removal of carbon
dioxide and other waste products from those
tissues more readily than if you're not
getting enough-- excuse me-- nitric
oxide into your system. So a lot of reasons to
be a nasal breather. If you want to check out that
book Jaws, A Hidden Epidemic, it's a terrific read. And it also shows some
absolutely striking pictures, twin studies and so
forth, and some before and afters of people and
the aesthetic changes that they experienced when
they shifted from being a mouth breather to a nose breather. These are striking
examples that have been observed over and over again. When people mouth
breath, there's an elongation of the jaw,
drooping of the eyelids, and the entire jaw
structure really changes in ways that are
not aesthetically favorable. Fortunately, when people switch
to becoming nasal breathers-- and, of course, that
takes some encouragement either by mouth taping or doing
their cardiovascular exercise with mouth closed or by
doing the sorts of exercises that we talked about earlier. When they switch to becoming
nasal breathers by default, the aesthetic changes that
occur are very dramatic and very favorable,
including elevation of the eyebrows, not
in an artificial sense or in a kind of outrageous
way, but elevation of the cheekbones,
sharpening of the jaw, and, most notably, improvements
of the teeth and the entire jaw structure. In fact, one simple
test of whether or not you can be an efficient
nasal breather and whether or not you've been
nasal breathing efficiently or most of the time in the
past or whether or not you've been relying more on
mouth breathing that was described in
the book Jaws is you should be able
to close your mouth and breathe only
through your nose. Again, this is at rest, not
during exercise necessarily, though you might do
it during exercise. But close your mouth,
put your tongue, on the roof of
your mouth, and it should fit behind your teeth. And you should be able to
nose breathe in that position. Now, many people won't
be able to do that. But fortunately, as
I mentioned earlier, if you nasal breathe, that is,
you deliberately nasal breathe when at rest for
some period of time, you will experience an increased
ability to nasal breathe. And you should also experience
some addition of space within the palate of your
mouth to allow your tongue to sit more completely on
the roof of your mouth. This is especially
true for children that perform this technique. Again, I refer you to the
book Jaws, A Hidden Epidemic. It's an absolutely
spectacular book. You can also just look online
"before and after Jaws, Hidden Epidemic" and look at
some of the changes in facial structure
that occur when people move from mouth to
nasal breathing, and it's really quite striking. So during today's
episode, per always, we covered a lot of information. First, we talked about
the mechanical aspects of breathing-- the lungs, the
diaphragm, the trachea, and so forth. We also talked about the
chemical aspects of breathing, that really breathing is
a way that we bring oxygen to our cells and that we
get the correct levels or, I should say, we maintain
the correct levels of carbon dioxide in our system, neither
too much nor too little, in order to allow
oxygen to do its magic and to allow carbon
dioxide to do its magic. Because as you learned
during today's episode, carbon dioxide is not
just a waste byproduct. It has very critical
physiological functions. You need to have
enough of it around. And therefore, you don't want
to overbreathe, especially at rest. We talked about
a tool to measure how well you manage carbon
dioxide, the so-called carbon dioxide tolerance test,
and various exercises that you can use
simply by breathing to decrease your
stress in real time, decrease your stress
chronically around the clock. Obviously, that's a good thing--
improve sleep, improve mood. How to increase
breath hold times and why you might
want to do that. Also how to eliminate hiccups. We talked about how
to breathe in order to eliminate the
side stitch or side cramp that you might
experience during exercise and how to breathe in
order to improve learning and memory, reaction time,
and various other aspects of cognitive and
physical function. I do realize it's a
lot of information. But as always, I
try and give you information that is clear,
hopefully interesting as well, and actionable toward a
number of different endpoints. So if you're somebody
that's just now starting to think about the
application of breathwork, I would encourage you to please,
yes, do that carbon dioxide tolerance test. That will give you some
window into how well or how poorly you're
managing breathing. And then here's the great news. The great news is
that breathwork, that is, deliberate
respiration practices, are very effective at
creating change very quickly. In some cases, such as the
use of the physiological sigh or cyclic hyperventilation,
those changes can be experienced the
first time and every time because, again,
these are not hacks. These are aspects of
your breathing apparati, including the mechanical
stuff and the neural stuff and the gas exchange stuff,
all of which you were born with and that are available
to you at any moment. So all you really have to do
is explore them and deploy them as you feel necessary. If you're learning from
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interest in science. [MUSIC PLAYING]
Been waiting for an episode on this. Going to do a Huberman/Attia crossover and listen to this during a long Zone 2 training session this morning.
Oh nice. I picked up The Oxygen Advantage from the library last week too so maybe I’ll have a breathing method festival this week.
Can someone post the synopsis from the podcast?
As a nasal breathing freak, kinda excited for this one. I can maintain nasal breathing while running with HR at 170-180, and refuse to sleep if I can’t breathe through my nose due to congestion lol
I don’t quite understand the physics of what he’s saying about nose breathing leading to greater air uptake due to a higher pressure differential caused by the smaller intake diameter. How do we square this with the fact that people switch to mouth breathing at a high enough exercise intensity to get higher air intake? I think I’m not quite grasping some nuance here.
Edit: I was pondering this more and think I understand now. With nasal breathing are moving less air per unit time but at a higher pressure which allows more volume per breath as you can fill the lungs fuller. Mouth breathing you’re moving more air per unit of time but at lower pressure, so can’t fill the lungs as full but can keep up with the air supply needed for increased metabolic demand.
Medlife crisis lambasting this on twitter was funny. Huberman definitely seems like he's running out of things to talk about. Still love him but damn
Transcript of this episode with timestamps : https://podscript.ai/podcasts/huberman-lab-podcast/how-to-breathe-correctly-for-optimal-health-mood-learning-performance/