- I used to think that sleeping was a complete waste of time. Your eyes are closed. Your body is motionless. I mean, how could sleeping be productive? You're literally doing nothing. I thought Dr. Strange was so cool because while he was sleeping, he'd
cast an astral projection form of himself to keep productive. In high school, I would pull all-nighters, sometimes doing homework but
mostly playing video games. In college, I would pull
all-nighters studying for my exams. Little did I know that
I probably would've been a better student and a better gamer if I had taken my sleep more seriously. Well, obviously, I was wrong, but it's not for the
reason that you'd expect. I'm not about to tell you that
sleeping is more productive because it helps you
recover energy for tomorrow. I'm sure you already knew that. It's more than that. If you look at the science of sleep, you'll realize that not
only is sleep productive, it might be the most productive
thing that you do all day. Hey, guys, if you're new to
the channel, my name is Mike. I make videos with my brother, Mattie. We're both doctors, and we
love talking about the science behind productivity and learning. New videos every week. Subscribe, and let's hang out. So recently, I started
my first job as a doctor, and half of my shifts
take place at nighttime between the hours of
5:00 p.m. and 8:00 a.m. At first, I thought it was fine. I mean, you get paid substantially more for working at night. Plus, when you work at night, you get more days off to recover, which meant that I could
work on making videos and music on my days off. But the hours quickly caught up with me. Sometimes I felt almost
hungover the next day. Sometimes it took me
multiple days to recover and reset my circadian rhythm. But the worst part was
that on my days off, I was unmotivated to do any
work, and I felt such brain fog, and I had a hard time
remembering and focusing. And this really bothered me. Like, what's the point of
having all these extra days off when you can't even use 'em? So I started to explore
the science of sleep, and what I found was
awakening, pun unintended. While we're sleeping,
we turn off our bodies but not our brains. During a full night of sleep, which is about seven to nine hours, our brains transitioned
between three different types of sleep, light sleep,
deep sleep, and REM sleep. We cycle through all three of these phases approximately every 90 minutes, but the important thing to
note is that every cycle is a little different. For example, the first sleep cycles right when you fall asleep
have more deep sleep, and the last sleep cycles
right before you wake up have more light sleep. So why does this matter? Well, some of you guys
know that I love analogies, so let me try to use an
analogy to convey to you just how productive our
brains are during sleep. And the analogy I'm gonna
use is about note-taking, (clears throat) RemNote. So you can think of deep sleep like taking and storing notes. So during the day, you've
collected all these notes into your little notebook. That little notebook in the
brain is called the hippocampus. Your notebook is just a
temporary storage space. During deep sleep, your brain
attempts to file away each of your new notes into a more
permanent place in your brain into the specific areas where they belong. So what happens if you
decide to stay up late and miss out on the first sleep cycle? Remember, these first cycles
are heavy in deep sleep. Well, you would risk not
properly storing away the hard-earned notes that
you collected that day. Basically, going to sleep
late means you don't give your brain the chance to save your work. And those notes could be lost forever because right after deep
sleep comes light sleep. Light sleep is like the janitor. It goes through your notebook and gets rid of all the leftover notes and papers that you didn't care to save because after being awake all day long, your notebook gets full, and light sleep's job is to clean it out and make more room to
prepare your hippocampus to learn new things the next day. When I stay up late trying
to cram new information, I sometimes find myself
rereading the same paragraph over and over again. My hippocampus, or my notebook, is full. I don't have the capacity to
cram any more notes in there. See, in college, I would
wake up super early to be productive and study, like I would wake up at 5:00
a.m. and try to get ahead. Well, what happens is if
you wake up too early, you lose out on your last sleep cycles, the ones that have the
most of your light sleep. So you might find it
difficult to learn new things because you haven't given
your brain the chance to clean out your notebook
and make room for new notes. So waking up early and only
getting like five hours of sleep is actually counterproductive. Finally, let's talk about REM sleep. During REM sleep, your
brain is making connections between all the old and new
notes that you've stored in your filing cabinets. And for all you RemNote fans
out there, no pun intended, REM sleep is when all the
bi-directional linking happens. You're trying to make sense
of all your stored memories and make new connections. That's why you sometimes
hear about all the artists or musicians or mathematicians
who had vivid dreams and wake up discovering
some new creative idea or some new breakthrough in their field. So just to recap, deep sleep
helps us save information, light sleep helps us
learn new information, and REM sleep helps us make
sense of our information. If you don't get a full night's sleep and you miss out on the
important stages of deep, light, and REM sleep, you'll remember less, you'll learn less and
you'll understand less. So based on the science of sleep cycles, you'll come to realize how important it is to get a full seven to nine hours of sleep when it comes to learning
and productivity. Now, when we're planning our sleep, a lot of us forget that lying in bed for seven hours doesn't mean
you're actually sleeping for seven hours. You could be laying there doom scrolling through social media or
tossing and turning for hours. I mean, I've had many nights
when I was physically lying in bed for seven hours, yet I only got like four
real hours of sleep. So the solution to this
is to train your body to fall asleep faster and to stay asleep. And there are a lot of a natural
ways that you can do this, like using pills and supplements,
technology, paid products, some of which are amazing and
some of which are expensive. Maybe I'll do a different
video covering those topics, but in this video, I'm gonna
take it back to the natural and fundamental methods, which also happened to cost nothing. So these natural habits are based on a simple sleep framework,
which is comprised of three factors, temperature,
timing, and light. Let's go through each one,
starting with temperature. So our inner body temperature is coldest in the middle of the night, and as we get closer to waking up, our body temperature automatically
rises and rises and rises until boom, you get
this boost of cortisol, and then you naturally wake up. When nighttime approaches, our body temperature starts to drop, and this makes us sleepy
to get ready for bed again. So now that we know how our
body temperature naturally works for sleep, how do we affect change? Well, an easy fix is to make
sure that your bedroom is cool. - Your body needs to
drop its core temperature by about two to three degrees
Fahrenheit to fall asleep and then to stay asleep, and it's the reason you
will always find it easier to fall asleep in a room
that's too cold than too hot. - Use fans or use less blankets if you get really hot
at night when you sleep. One of my favorite things to
do is to take a warm shower before bedtime 'cause when
hot water hits the skin on the outside of your body, you react by trying to cool down from the inside of your body. Therefore, taking a warm shower causes your body's temperature
to drop in response. The opposite is true for cold showers. The cold water makes your body react by heating up your inner body temperature. That's why you see people taking
cold showers in the morning to wake themselves up. Next, let's talk about timing. Our brain is conditioned
by habits and rituals, and if you go to sleep at
the same time every day, preferably in the same bed every day, your brain gets used to it and helps you establish a
regular circadian rhythm. - Regularity is probably
the most important thing I can tell you. Go to bed at the same time,
wake up at the same time, no matter whether it's
the weekend, weekday. Regularity is key. - Take myself, for example. Depending on what kind
of night shift I'm on, I'm forced to sleep at a different time, and I'm assigned to a different call room with a different bed. So over time, I found it harder
and harder to fall asleep because I've lost the regularity. And even when I get home, I'm unable to sleep during the daytime. And finally, let's talk about light. When we view light, like
when light hits our eyeballs, there are certain chemical reactions that happen in our brain that kinda resets our circadian rhythm. The simple way to think about
this is you want as much light as is safely possible early in the day, morning and throughout the day, and you want as little
light coming into your eyes, artificial or sunlight,
after say 8:00 p.m. And certainly, you do not want
to get bright light exposure to your eyes between
11:00 p.m. and 4:00 a.m. - So the goal is to get the
right kind of light exposure at the right time in
order to get good sleep. After you wake up, make sure there is plenty
of light around you, and the best way is to have
natural light just pour into your bedroom, or if you don't have that, go
outside or onto your balcony for like five to 10 minutes
with a cup of coffee if you want. Then at night, you wanna do the opposite. You wanna limit the amount of light that's hitting your eyeballs. That way, you can get ready for bed. So let's put all three of these together. An easy way to clean up your sleep habits is to use a night routine. Routine is where timing comes in. Have established bedtime,
and keep it regular. About an hour before you plan to sleep, start wrapping up your work and start turning down the lights and try to avoid too much
light coming from screens. And finally, it might be helpful to take a quick, warm
shower to rinse your body, bring down your body temperature and get you feeling nice and
clean before jumping into bed. So as you can see, getting enough quality sleep
makes you more productive, and it makes you smarter. Now, if you want a more
in-depth, step-by-step approach to changing your habits, check out our free course on Skillshare. Link in the description below. But if being smarter and
more productive is not enough to inspire you to get better sleep, then consider sleeping
in order to live longer. But that's a discussion for another video. In the meantime, check out
this video where I talk about the type of sleep
that you want to avoid. You can watch it by tapping
on the screen right here. (upbeat music)
