We spend one-third
of our lives sleeping and still we donât know why we sleep. We know some functions,
but overall itâs still a mystery. From the beginning of time, all living beings have been
governed by the need for sleep. Sleep is considered
one of the critical, necessary components to life. If you donât sleep, if an
animal doesnât sleep, it dies. Yet for many modern-day humans, a good night's sleep
has become elusive. Being exposed to
light, even at low-levels, has an adverse effect on sleep ... even just the equivalent of a couple
candles a meter away from you. You need to know how
to switch off at night. And, above all, never
use a screen after 8pm. Thatâs one of the reasons
that has contributed to this epidemic of sleep
deficiency that is in our society. Today, lack of sleep
affects all age groups. Insomnia is very common. Itâs estimated that nearly
10% of adults around the world are severely insomniac. In the space of 50 years, weâve lost some one-and-a-half
hours of sleep per night. Scientists around the world
are racing to find solutions. But how do you recover sleep
thatâs been lacking for so long? Anything's worth a try, from
the most natural remedies, to the most high-tech! I donât face the night
like Iâm not going to sleep. I donât have that
anymore. Thatâs gone! In just two generations, weâve lost
around 90 minutes of sleep each night. Today, the average European
sleeps less than 7 hours a night. Worse still: One out of three 18- to 35-year-olds get fewer than six
hours of rest a night. One reason is the
omnipresence of blue light. It doesnât just bother us
when the time comes to sleep; it also throws our
everyday lives out of sync. Adolescents fall
asleep later and later. Half of them suffer greatly from
sleep deprivation or âsleep debtâ. Today, the per-capita exposure
to light is about ten times more than it was 50 years ago. So lighting is ubiquitous. You know, we would have
one lamp in the living room and electricity was so expensive. I
remember my father would be like: Turn off the light! Are
you paying for this? And now, itâs so much
cheaper to keep the lights on that the ceilings are
covered with built-in lights and, when you switch on, youâre being bathed in
blue-enriched light, in many cases. And youâre not tired. We share in common
with many other species â plants, animals, insects â that the light-dark cycle is the
most important synchronizer of our internal biological clock. Professor Charles Czeisler is the
father of modern âchronobiologyâ â the science of our
bodiesâ internal rhythms. Heâs investigated the effects
of natural and artificial light. Since the dawn of time, most living species have been
downright bombarded with the white light emitted by the sun. White light is composed
of a palette of colors. They range from red to violet,
but the blue tones predominate. LEDs could not make white
light because no-one knew how to make a blue LED. So, when the scientists
discovered how to make a blue LED that has
created an entire revolution. Before then, we used incandescent
lightbulbs with heated filaments. These were replaced
with energy-saving LEDs. And this is where the
problem lies today... Since the advent of blue LEDs, each bulb in our homes emits
the white light of a small sun. All our screens use
this same technology. They flood us with blue
light, without us noticing it. Now, the electric light
to which weâre exposed, in terms of resetting our internal
clock, is like light on steroids. It has this tremendous peak
in the blue part of the spectrum. Itâs telling the brain: âOh my goodness, itâs
the middle of the daytime!â Our main biological clock
is located in the brain, right behind the optic nerve. It is synchronized by sunlight,
and controls all our bodily rhythms. This clock is set to a 24-hour cycle: the time it takes the Earth to
complete one rotation on its axis. So what happens if we are
constantly exposed -- day and night â to light that is not sunlight, but
which the brain interprets as such? As we have reduced the strength of the synchronizing
effect of solar light, and increased the disruptive
effect of electric light, it has dispersed us, because
we donât think about it. We turn on the lights to
do things in the evening. After the sun sets,
we turn on the light. We donât think about the fact
that when we turn on the light, it is shifting our circadian
rhythms to a later hour. So, all of us on average, compared to where we would
have been 200 years ago, we have shifted ourselves about
three to five time zones westward. Weâve actually studied
people, here in Boston, who are living in the same city and their internal clocks
are twelve hours apart. So, I mean thatâs just
a mind-boggling finding. So one personâs internal
clock will be on Hawaiian time, and the other personâs biological
clock will be on Paris time, and theyâre both living in Boston! And then we wonder why weâre having
trouble falling asleep at night. This is precisely what Professor Claude Gronfier is
trying to understand. In his lab, he conducts
isolation experiments to determine participantsâ
photosensitivity. Our experiment is designed
to answer the question: With a light intensity
equal to whatâs in this room â so, around 150 to 200 lux, or what you might have in
your kitchen after sundown â how long does it take for
this light to activate the brain? To find the answer, Professor
Gronfier studies the effect of light on test subjects who spend
three days in total isolation, with no temporal reference
points â and no sleep for 34 hours. I'll let you settle in.
This is your room. I hope you were told
to take off your watch. Youâre not wearing one? No. I just have my
phone, but I'll turn it off. Ok, LoĂŻc. We're going to close the
door and start the experiment. We'll open it again on
Thursday, okay? See you! Let me show you
what we're looking at. We want to calculate
the size of your pupils when theyâre exposed to light. Once the light starts to
bother you, click this button. Various kinds of light activate
different kinds of photoreceptors. The participant is subjected to
this same lighting every 2 hours. This helps us determine if
there are certain times of day when weâre more affected
by light than others. Our results show that it
takes between 2 and 5 minutes for light to activate the brain. The pupils constrict rapidly, the heart rate shoots up, as
does the body temperature. So clearly, light activates
many parts of the body. Melatonin is the hormone
that induces sleep. Itâs produced
naturally in the brain â and is particularly
sensitive to light. We've been able to show that
even very low levels of light, between 1 and 2 lux - the equivalent of a couple of
candles a metre away from you â can reduce melatonin
secretion by 10%. So we've gone from thinking that very high levels
of light were necessary, to observing effects
at very low levels. For instance, the light you're
exposed to in bed in the evening emitting from a cell
phone, tablet, or computer. Incessant light pollution has
an impact on society as a whole. Day and night, swarms of people work in shifts to
meet growing production demands. There are 25 million shift
workers in the United States alone. The consequences are dramatic. Shift workers who continuously
shift from daytime to nighttime, flight attendants who are flying
continuously across time zones, they have an increased risk of cancer. People who sleep five hours a
night or less have a 300 percent increased risk of calcification
of the coronary arteries. Weâve shown that
when resident physicians work extended duration shifts, they make significantly
more serious medical errors. They stab themselves more
often with needles or scalpels. The more senior physicians
have an increased risk of making a serious error
in a patient during surgery. They have a 170
percent increased risk of having a motor vehicle
crash driving home from work. So, there are many adverse
effects of insufficient sleep and extended work hours. For those who cannot
escape shift work, an otherwise healthy lifestyle can
help improve their quality of sleep. Nutrition, for example,
plays an essential role in stabilizing our sleep-wake rhythm. Eve Van Cauter is an endocrinologist
and metabolism specialist. Sheâs headed a vast study on the links between sleep disorders and obesity. When you start analyzing
hormonal data over the 24-hour cycle, you recognize that there are some
events that have a major impact. And the one event that has
the biggest impact is sleep. We are the only mammalian
species that sleep-deprives itself, so itâs a behavior that is
completely abnormal and artificial. We started inquiring
about whether this behavior could actually be involved
in the epidemic of obesity, which affects all industrialized
countries on every continent. Two hormones
regulate our appetite: Leptin decreases appetite,
while ghrelin increases it. That was just amazing, that these two molecules
measured in the blood were able to predict how much
more an individual would be hungry due to that sleep restriction. We know from previous studies that sleep restriction is
associated with an increased intake of high-carbohydrate
and high-fat foods, so one of the questions I have is: What is involved in this increased
drive for highly palatable foods? When thereâs not enough
sleep, everything goes wrong. So leptin goes wrong,
ghrelin goes wrong and endocannabinoid
is dysregulated. And thereâs not a single system that
is not affected by the lack of sleep. So, our study addresses
that issue of how dietary intake can help synchronize or
desynchronize the peripheral organs that are sensitive to dietary
intake, which is many, many of them,
from the brain clock. Claudia is slightly overweight. Sheâs agreed to take
part in Eve Cauterâs study. Sheâll spend one week at home, then another week
at the hospitalâs lab. The goal is to better
regulate her meals, to allow the brain to rest at
night and help her sleep better. Eating too often
keeps the body awake, which upsets the essential
fasting phase during the night. So we have you sleep in
the lab around the same times that you sleep at home. Weâll ask you to wear
this watch the whole time. You will press this button
on the side when you wake up and when you go to bed. And then we have something
called the constant glucose monitor. Are you ready? One, two, three. There it is, thatâs it. So every night, weâre
going to wand the sensor and weâll be able to
see what youâve eaten, when youâve eaten across the day, and what your glucose
levels were. OK? Awesome. Dark, sleep, fast. These three things have to be aligned for our biological clock
to be able to control temporal organization
in all the organs. The clock in the brain is
synchronized by the light-dark cycle, but the clock in the
liver doesnât see the light. So what is synchronizing
the clock in the liver, in the pancreas, in muscle
and so on... is caloric intake. The experiment is being
carried out on several subjects, under different conditions. As Claudia settles into her room, Eve Van Cauter and Erin
Hanlon analyze the results of one of their first participants,
who arrived a week earlier. So this subject was the first subject and he was randomized to
the extended overnight fast. And his biggest meal,
always in the evening. And fairly late, starting at 8;
for an American thatâs late. And day after day, this
is the mean of five days, you cannot see where
the overnight fast is. It looks like his glucose
levels are all over the place across the 24-hour cycle. And then you can see that
he is definitely prediabetes. The lower curve
is our intervention. And there we can really see
that we changed the glucose levels to a clear low overnight
fast, breakfast, lunch, dinner... So Iâm really excited. As a result, the
patient's quality of sleep has also improved markedly. The brain is a glucose guzzler. It needs glucose,
itâs its main fuel. And it uses more glucose
than any other organ. As soon as you fall asleep,
your brain is not using as much, so the metabolism is
slowed down drastically. So what happens
when you eat very late? Instead of having the
glucose go down in three hours, it takes five hours, six hours. So most of the night, you
have high glucose levels. The signal to the brain
is that we are awake. Sleeping over
high glucose levels is going to deteriorate
sleep quality. This study points to a
terrible vicious circle: The more often we eat at the
wrong times, the less we sleep. And the less we sleep,
the hungrier we become. How can our brains rest if our food
intake is so frequent and so heavy, that it simulates us
being permanently awake? Clearly, our bodies have been unable to adapt to our modern-day lifestyle. Too many changes in
the space of just a century deeply affected our
circadian rhythm. Similarly, our bodies have not
been able to grow accustomed to the increasingly
sedentary nature of our lives. At the University of Caen,
Professor Damien Davenne conducts research
on biological rhythms. Heâs looking to determine
the impact of physical activity on the quality of nighttime sleep. The homo sapiens are designed
to move, to exert themselves. Up until the 20th century, burning 3,000 to 4,000 calories
a day was nothing unusual. This high energy turnover was
enough to keep people in good health. We want to see if
isolated physical activity at a specific time during the day has immediate
consequences that night. Physical activity triggers the
secretion of waking hormones, which need to be eliminated
in order to sleep well. And the more intensive
the physical activity â a squash match, for example, thatâs very demanding
and requires a lot of energy â the harder it is to sleep afterwards. Before we can get
a good night's sleep, we need to release pressure and
return our temperatures to normal. We started asking ourselves what type of physical
activity could improve sleep, and we concluded that
it was aerobic exercise. Aerobic exercise is a
form of endurance training. While performing it, muscles
draw oxygen from cells â unlike during quicker, more
high intensity exercises. Once the physical activity is done, professor Davenne
analyses the subjectâs sleep. Weâre looking to see if
his sleep is more intense, his deep sleep in particular. Right now heâs still awake, with
considerable muscular activity, but heâs falling asleep quite quickly. These are what we call spindles;
they occur as we fall asleep. The optimal time for physical
activity is the late afternoon. Then, its effect on
our sleep is ideal. Endurance sports carried
out in the late afternoon help realign our internal clock, making it much easier
to fall asleep at night, and improving the
quality of deep sleep. These days, the combination
of abundant artificial light, a poor diet and the lack of exercise are the root causes of sleeplessness. Other factors, in particular
stress and anxiety, also play a role. One-third of Franceâs population
regularly have trouble sleeping. 6 million combat their
insomnia with medication. I've been an insomniac
since I was 20. I know it started before then, but that was when I
started taking sleeping pills. âHappy to see me? You
were all alone, werenât you? Come on, letâs go for a walk!â I know that, in order to sleep well, I should to be in a
completely dark room, and only go to bed when
once Iâm ready to fall asleep. But I start watching
TV right after dinner. And I don't watch in the living
room, I go to my bedroom, and take my computer
and my phone with me. I know these arenât the best
conditions for me to fall asleep. But I canât help myself,
these are the moments I savor. My dream would be
to give up the pills. Worldwide, 600 million
people suffer from poor sleep. One in five Americans admits
to having taken sleeping pills. In Europe, Spain holds the
record, just ahead of France, where 131 million packets
of sleeping pills are sold each year. Trouble falling asleep, jolting
awake in the middle of the night, stress, anxiety... insomnia has a number
of causes and effects. Insomnia is defined
by strict criteria: trouble sleeping, at
least three times a week, over a period of at
least three months, with the consequences severe enough to have an impact the following day. Tell me a bit about
your trouble sleeping! If I donât take pills, I donât
sleep. I lie awake all night. Ok! And whatâs your goal? Iâd like to do without
sleeping pills entirely. Getting myself off them
would be wonderful! So what we're going to do
is to record your sleep cycle to try to understand exactly what
happens when you fall asleep, and while youâre sleeping. Then we can assess, bit by bit, how to
help you sleep without - or using far fewer sleeping pills. Bonjour, Madame!
- Bonjour! Ready for your polysomnography? Yes. See you later! Iâll take you to the sleep lab. This will register your eye
movements while you sleep. Depending on the
stage of sleep youâre in, your eyes move
in different ways. This device will record your sleep, and tomorrow morning
weâll download the data. A number of sleep
cycles occur in one night. One complete cycle lasts about
90 minutes and contains 4 stages: falling asleep, light
sleep, deep sleep, and the REM phase of rapid-eye
movement during which we dream. This cycle is repeated 4 to 7
times in the course of a normal night. So, itâs very important to
go to bed when youâre tired. The test showed you have
great difficulties falling asleep. It took you nearly 45 minutes. And then you woke up frequently
during the first part of the night. That canât be normal. No, itâs not. It means your sleep
is easily disrupted and fragile. This here is the
spectral analysis we use to measure your brain
waves while you sleep. Here we see very rapid waves, almost as fast as at
the start of the night. They show that the brain
hasnât completely settled down. In your deep sleep cycle, the waves become much
longer and more restorative, but unfortunately thereâs
not enough of them. Thatâs quite typical for insomniacs. So, I have trouble falling asleep and when I finally
do, Iâm still awake? Yes. While you sleep you keep
having periods of wakefulness, which get longer and
longer as the night goes on. It seems that, at least this night, the medication wasnât
effective enough. As the name suggests, a sleeping pill is a
drug that induces sleep. But thatâs not true. Itâs not really sleep,
but a light narcosis. The patient is half-dozing. The most common sleeping
aides are benzodiazepines, from the family of drugs
used as minor tranquilizers. They have sedative, hypnotic
and amnestic properties. They numb the entire
brain, inhibit memory and are extremely addictive. Theoretically, sleeping pills should
only be prescribed for four weeks â sedatives for 12 weeks â maximum. Yet the reality is quite different. When benzodiazepine was first
discovered, people were thrilled. While I was studying we were told
to prescribe as much as we wanted for however long we wanted. It took decades before we learned about its long-term, chronic toxicity. And thatâs the problem. Itâs not toxic right away, only when you take it
over a long period of time. Sleep disorders affect
people of all ages. But itâs the older generations who suffer the most and seek
medical help most frequently. In Lyon, psychiatrist Patrick Lemoine heads group therapy sessions for
the French association for insomnia. France is the country with the
second-highest consumption of sleeping pills in Europe. Nothingâs worse than a
symptom-centric therapy: âYouâre in pain? Take a painkiller!
Canât sleep? Take a sleeping pill! Youâre anxious? Use a sedative!â
We should be treating the cause! I wake up a night and wander around. I canât sleep at all! My insomnia manifests
itself in nightly waking states I just canât get a handle on. When I was young, I slept normally. Then I had my fourth child, who
suffers from Down Syndrome. Theyâre 53 now, but Iâm
still constantly worried. Insomnia is always caused
by a sense of insecurity. Why does this person feel
unsafe? Why is she afraid to sleep? What has kept her
vigilant all these years? Thatâs what we need to understand. Could illness or
anguish be causing it? I know when my
trouble sleeping started. When was that? We can talk about
that here? I was very ill. I didnât think I could
talk about that here. Wouldnât illness be a good
reason to feel uncertain? Well.... yes! The most common cause of
sleep disorders is depression. And treating depression
with sleeping pills just worsens the depression. At the sleep center
of his hospital in Paris, Professor LĂŠger prescribes Nathalie
two different kinds of treatment. Sheâll start with
mindfulness exercises, which should help with
the drug withdrawal. Our goal is for you to get a better
sense of your current feelings, thoughts and experiences, so
you struggle against them less. I understand. Then letâs stand up! Keep your eyes open... ...and slowly raise your arm. Can you feel the
position of your arm? Yes ! Now lower it and
raise the other arm. Do you feel it? Now lower it and this time try raising your arm
only in your imagination. Okay. Retrace this posture
with your eyes closed. Can you feel your arm moving,
though youâre not really lifting it? A bit. Yes. Youâre using your sensory imagination. Youâre imagining a
movement of your body... Mindfulness meditation
involves focusing on the present â without letting other
thoughts distract you. I recommend you keep practicing. This training helps
us work on ourselves. It helps us to accept our
thoughts and feelings which, in your case, will lead
to a better nightâs sleep. Professor LĂŠger also
prescribes light therapy. These sessions
primarily use blue light, because this color amplifies
the positive effects of natural light and increases alertness
during the daytime. Phototherapy also
regulates the biological clock and helps combat depression. The principle of phototherapy
is help to re-synchronize your biological clock,
your wake-sleep rhythm. You can start pedaling! If Iâd known, Iâd have worn trainers! Not to worry, you can
bring them next time. Pedal at your own rhythm, that's it. It isn't a marathon
or the Tour de France. Look at the wall;
look at the blue light. This is an alternative to medication. Enjoy your session. Thanks, see you later! During the day, exposure to natural light
combined with physical exercise improves the quality of our nights. So, our day-time activity
clearly influences how we sleep. I believe there are just
two clinics in France with resynchronization
rooms like this â one in Strasbourg
and this here in Paris. While this treatment is not
covered by public health insurance, itâs very effective for a
whole range of patients. Poor sleep can even be a risk
factor for Alzheimer's disease... ...as Professor Maiken
Nedergaard has discovered. The brain is so stressed
out during normal wake time that it cannot do its
normal housekeeping, and we speculated that this might be the biological foundation for sleep. The purpose of sleep is to clean
the brain of all the waste product that builds up during wakefulness. Nobody had really looked in
the brain on how does the brain get rid of waste products. So weâre starting to wonder, would glial cells
be involved in that? Glial cells nourish our neurons, supplying
them with oxygen and nutrients. However, thanks to Maiken
Nedergaard's discoveries, we now know another major
purpose these cells serve: In the brain, the arteries
are surrounded by space in which cerebrospinal
fluid circulates freely. When we fall into a deep sleep, glial cells open canals
which release this fluid. It washes over the neurons,
clearing away the waste thatâs collected there
during our waking hours. So these cells are
key to brain cleansing. And once itâs transported
out of the brain, itâs dumped back into
the blood circulation, and you can regard the liver as
our professional recycling plant. Doug Kelley is an engineer
specializing in fluid mechanics. Heâs constructed the first model
which shows how this cleansing system operates in the brain
of a sleeping mammal. Hereâs the middle cerebral artery at the surface of the
brain of a live mouse. Blood is flowing through
it, but of course our interest is the cerebral spinal fluid thatâs flowing through
the spaces around it. So that is really what is
happening when weâre asleep. We have all these
many milliliters of fluid running through
our brain to clean it. This flow is much more efficient
when we are in deep sleep. If you are in lighter stages
of sleep, or if youâre awake, it does not work. So, the deeper your
sleep, the longer your sleep, the better you clean the brain. Maiken Nedergaard has discovered that the waste being washed
away is an amyloid beta protein. Its accumulation is
directly associated with the development
of Alzheimer's, a disease which already affects
some 50 million people worldwide. And that number keeps growing. Once we get elderly,
and sleep less well, clearly we start to accumulate
some of this waste product. And those waste products are viewed by the brainâs
immune system as a foreign object, because they are not
supposed to be there, and the brain will start an
immune response to remove it. And that immune
response, on long term, is actually very damaging
for the nerve cells. You have an increased risk
of developing Alzheimerâs if you donât sleep. The medical industry has spent
billions of dollars trying to block the production of beta-amyloid, hoping that would cure
Alzheimerâs disease. It didnât work at all, simply because it is
not a production problem; itâs a clearance problem. These discoveries could lead to new
and far more effective treatments â for Alzheimerâs and sleep disorders. But, in the race for new remedies, alternative treatments
are also being studied. Inspired by meditation and yoga, this Paris-based
company has reinvented the concept of cardiac coherence. All of these methods
have one thing in common: slow breathing and
concentrating on an external point. We wanted to concentrate
the best of all approaches into one simple product
thatâs accessible to everyone. We wanted to develop a simple device. Today thereâs a lot of talk of
high-tech, connected products. But we wanted a disconnected product. To fall asleep, you must be offline. To turn it on, you simply
swipe it with your finger, and it projects a circle
of light on the ceiling. Now we synchronize our
breathing with the light. When the pool of light
grows larger, we breathe in. When it shrinks, we breathe out. And we do that for a long as possible. The exercise lasts eight minutes. By slowing down their breathing, this
little device helps patients relax. Itâs now recommended by many doctors. We didnât really
invent anything new. People have been talking about
cardiac coherence for years. Even skippers use it. Anyone sailing solo
can only take micro-naps and must learn how
to fall asleep quickly. Naps are actually an
important key to better rest. At the Sleep and Cognition
Lab at the University of California, Irvine, theyâre studying
this tried-and-true method. Sara Mednick is a
professor of psychology here. She uses neuroscience
research to demonstrate the central role naps can
play in sleep management. The purpose of the research
weâre doing at UC Irvine is to understand what are
the basic mechanisms of sleep that support cognitive function,
including emotion regulation, memory, creativity, alertness. We look at what is the brain activity using electroencephalography or EEG, to look at specific sleep features
that occur during that sleep period, either a nap or a nighttime sleep, and see how those sleep
features relate to the improvement in performance that we see
before and after the sleep. Ok, now weâll set you
to sleep. Time for a nap. So, a nap we would
say is anything from, say, five minutes to about three hours. The ideal nap time is usually about
six hours after youâve woken up. If you nap earlier than that period, youâre going to have
a nap that has more rapid eye movement
sleep, REM sleep. If you nap later, youâre
going to have a nap that has more slow-wave sleep. These are two very
important sleep cycles, and they contribute to very different
types of performance improvement, so really it also depends on
how you want to tailor your nap to suit the goals of your sleep. If you wanted to
have more, sort of, steady help in terms of
learning your history lesson, maybe you want a sleep
with more slow-wave sleep and you donât really need REM sleep. Versus, if youâre somebody who has
to come up with some creative ideas, that will require REM sleep. If you wanted to just have a
quick alertness reset button, booster, then you would just
have these short power naps, these thirty-minute naps, and you
could do that anytime during the day. Finding sleep is about
finding a healthy lifestyle: sleeping and eating at regular
times, getting enough exercise and, of course, avoiding screens and blue light in the
evenings as much as possible. By respecting sleep and
our circadian rhythms, we can strengthen our memory. And put fatigue and stress to bed.
I was watching this on my phone in bed, better bookmark it for tomorrow