Nova (1974–…): Season 47, Episode 4 - Mysteries of Sleep - full transcript
Scientists study why animals and humans need to sleep, what happens to the brain during sleep, and the role sleep plays in memory, trauma, and emotion regulation.
Sleep. We all do it. But why?
Sleep remains one of
those remarkable puzzles.
We've known the functions
of eating, drinking,
and reproducing
for thousands of years.
However, sleep
remains a mystery.
Why do some people ruminate
all night,
and other people,
they see the pillow,
they're gone?
Cutting-edge research is
now giving us a new view
inside the sleeping brain.
How can we boost and enhance
sleep quality, sleep quantity?
It's really, right now,
the tip of the iceberg.
If you've ever thought of sleep
as a waste of time,
think again.
The more we learn about sleep,
the more we realize
that we can't dismiss it.
Getting a good night's sleep
is possibly the single
most important thing
you can do every day.
"Mysteries of Sleep,"
next, on "NOVA."
Major funding for "NOVA"
is provided by the following:
one of the most enduring
mysteries in all of science.
We spend a third of our lives
asleep,
in this kind of unconscious,
unresponsive, immobile state.
I mean, we can't do
any of the things
that we think are important
for our lives, like eat,
care for our young, mate.
Why do we spend
a third of our lives
in such an unproductive
and defenseless state?
What is that thing
that sleep does
to our brain and our body
every single night
is very much an open question.
A question that has baffled
scientists for centuries.
It's like this big black hole.
We don't really understand
why is it that we sleep
and what happens in our brain
when we're asleep.
But in the last decade,
sleep researchers
have started to unravel
the mysteries of sleep,
and what they are discovering
is mind-boggling.
Many people think that when
we sleep, we are unconscious,
so the brain is
sort of shut off.
But the more we explore it,
the more it's clear
that the brain is not shut off.
In fact, we find that
the brain is just as active
when we're asleep
as when we're awake.
'S just active
in different ways.
You're not either aware
or not aware,
you're neither not conscious
or unconscious.
It's a whole spectrum.
So, what exactly is sleep?
And why do we need it?
One thing that is for certain,
when it comes to sleep,
we've got a lot of company.
What we're fast learning
is that sleep isn't a luxury;
sleep is a biological necessity.
I find it fascinating,
because every animal sleeps,
every animal
that we've studied...
from worms to jellyfish
to sea slugs.
Even the octopus, whose genome
is so different from our own,
they sleep about as much time
as we do.
Sleep is one of the most
essential elements of life,
actually.
Sleep and life evolved
hand-in-hand.
Evolution has come up
with a variety of ways
to get some shut-eye.
Some animals are vulnerable
when they sleep.
And other animals are not.
And the animals that are
vulnerable when they sleep
don't sleep very much.
If animals live in the open,
they obviously have to be alert.
And they can't sleep as deeply.
You know, if a giraffe slept
the same way a lion slept,
there wouldn't be any giraffes.
Now, on the other hand,
there are animals
like the big brown bat,
which is the champion sleeper...
sleeps 20 hours a day.
It sleeps on cave walls,
so it's pretty much
invulnerable there.
But perhaps one
of nature's most innovative
sleep solutions
is found under the sea.
One of the really cool animals
that people study
is the dolphin, which actually
has unihemispheric sleep.
Half of the brain has
a sleep-like state
and the other half has
a wake-like state,
so the animal has to have
one hemisphere awake.
In fact, if you anesthetize
dolphins, they stop breathing.
And in the fur seals, such as
the one swimming behind us,
when the right hemisphere
is asleep, the left flipper,
which is controlled
by the right hemisphere,
is inactive,
and the body's posture
is asymmetric.
So by looking at a fur seal,
you can tell
which hemisphere is asleep.
Fur seals and dolphins
aren't alone.
Human sleep is equally complex,
weird, and mysterious.
I would say my favorite animal,
in terms of how animals sleep,
are humans.
Human sleep is very broad.
Each individual has their own
personal experiences with sleep.
So, what exactly is happening
inside our brains when we sleep?
We've really entered a different
world once we're asleep.
I actually think
that the whole night
is a really magical event.
With the help of volunteers
like five-year-old Jaime Lopez,
sleep researcher Rebecca Spencer
gathers clues
to how this magical event
unfolds.
Just slip this on,
just like last time.
To study sleep, we equip Jaime
with a sleep cap...
Shake, shake, shake, shake,
shake, shake, shake.
...with an array of electrodes
to record brain activity.
- Yeah.
- There you go.
The way our brain supports
everything that it does,
from controlling our body
to regulating emotion,
having memories,
is through the electrical
activity of neurons.
These are brain cells
connected to one another
via these tiny passages
that are called synapses.
One neuron emits a neurochemical
called a neurotransmitter
to this passage,
and it's picked up
by the next neuron,
much like passing the baton
in the Olympics.
This signal,
passed from neuron to neuron,
can be picked up by the
electrodes in Jaime's cap
with one of the
most powerful tools
in a sleep researcher's
toolbox...
the E.E.G.,
the electroencephalogram.
What this screen is
showing is the recordings
from each of those electrodes
in the cap that we put on Jaime.
Right now, in wake,
for instance,
you know, you can see
the brain waves here.
The vertical lines on the chart
represent five seconds
of Jaime's sleep.
What's important is
that as you get drowsy,
those waves slow down,
and they become
what we call alpha waves.
And as the sleep gets deeper,
the waves become
slower and slower,
and in the deepest parts
of sleep,
activity's dominated
by slow waves,
these massive waves
occurring across the brain
that are like a tsunami.
It's almost
like a football stadium,
where all of the individuals
in the stadium
before the game
are all sort of speaking to
each other at different moments,
at different times.
That's what seems to happen
when you're awake.
But when you go into
the deeper stages of sleep,
all of a sudden,
the crowd starts
to synchronize its activity.
They all start to chant in time.
Thousands of neurons,
firing in unison.
That's your deep sleep.
That's when it's hard
to wake you up.
When you wake up someone
who's been in slow-wave sleep,
and we ask them what they
were thinking, they will say,
"I don't know,
I wasn't thinking anything,
"I was asleep... leave me alone,
go away,"
and they'll push you off.
But Jaime...
along with the rest of us...
doesn't stay in deep,
slow-wave sleep all night.
At a certain point,
his brain waves change.
After about 50 or 60 minutes,
your brain will start
to rise back up.
And then it will pop up and
have a short REM sleep period.
Turns out that those two types
of sleep, non-REM and REM,
will play out in a battle
for brain domination
throughout the night.
And that sort of cerebral war
is going to be won and lost
every 90 minutes.
We spend most of the night
in non-REM sleep.
The rest of the time we spend
in the mysterious stage
of REM sleep.
It's hard to investigate
REM sleep
without investigating dreams,
because more than 80% of REM
periods would include a dream.
Dreams tend to be emotional.
One idea is that we dream
to simulate potentially
negative events
so that we're prepared for them.
I had a dream,
when my daughter was very young,
that she fell
into the swimming pool...
she was near drowning.
After that, I put my daughters
into swim lessons,
and water safety has been
important to me.
It's not that we do not dream
in the other sleep stages...
we do...
but the most vivid ones
are in, in REM sleep.
REM sleep is named
for the rapid eye movements
we make when we dream.
We believe that every time
the eyes move in a dream,
it's a special moment
where we sort of switch
to the next dream scene,
if you will.
As we switch
from one dream to the next,
our brain waves are doing
something downright strange.
With REM sleep, the brain waves
look just like waves
from when you're awake.
We have this paradox
that it's a state of sleep,
but yet our brain is
in a state of activation.
But perhaps the strangest
feature of this stage of sleep
is what's happening
in your body.
During REM sleep,
our brain actually sends
the instructions
to the different muscles
to move our body
as if we were awake.
But lower down
in the brain stem,
these instructions
are disrupted.
They are not relayed
to the body,
and the body remains paralyzed.
Otherwise, if we had a dream
where we fly above the city,
we would literally
jump out of the window.
From the dreams of REM sleep,
we cycle back
into non-REM sleep,
including the deepest stage
of sleep, slow-wave.
In the first half of the night,
the majority of those cycles
are comprised
of deep, non-REM sleep.
Yet, as you push through to
the second half of the night,
now that ratio balance shifts;
and instead, the majority
of those cycles
are comprised of much more
rapid-eye-movement sleep...
dream sleep...
and a lot less
deep, non-REM sleep.
What is crazy about this is,
the pattern is
so absolutely reliable
in virtually everybody,
every night.
It speaks to a fundamental,
genetically driven program
that is essential
for being a human being.
You have to go through this.
But if every one of us
needs a night full
of both slow-wave and REM sleep,
why is it such a struggle
for so many of us
to get some shut-eye?
The search for answers
has become
a multibillion-dollar industry,
selling us everything
from sleeping pills
to ergonomic pillows.
And if they don't do the trick,
there are more than 3,000
sleep clinics nationwide,
a number that keeps on growing.
Are you up all night tossing,
turning, mind racing,
trouble getting to sleep,
trouble staying asleep?
Drew Ackerman has
created a podcast
to help the sleep-deprived
get their Zs.
The idea for the show
really sprang
from my childhood insomnia.
When I was a kid, I lost
the ability to fall asleep.
For me, it was anxiety-related.
My parents tried to help,
but because they could sleep,
I think there was,
like, this disconnect.
It's, like, "Oh, try to relax,
try to just think
about something nice,"
and I just couldn't do that.
Whatever's keeping you awake,
thoughts,
you know,
things you're thinking about...
Drew's goal is to be
as boring as possible.
I'm going to tell you all
a bedtime story.
I want you to get comfortable.
The podcast is not
straightforward,
it's full of nonsense.
I have a unique hobby,
my dog and I.
We listen to recordings
of people knocking on doors.
It gives people permission
not to listen,
or to only kind of listen.
I want no social pressure
on the listener
to pay attention to me at all.
And there's no shortage
of people
eager to tune out.
Each month,
the show gets downloaded
a little bit
over three million times.
What I'm going to do is,
I'm going to send my voice
across the deep dark night.
People that listen to the
podcast share that feeling...
I don't know if desperation
might be a strong word...
but that feeling where
you're just lying there in bed,
and you feel alone.
How many people listen
to the podcast
because they have trouble
falling asleep?
Like, if you want,
raise your hand.
Having trouble falling asleep
or staying asleep
are symptoms of the most common
sleep disorder on the planet.
Ten percent of all people suffer
from chronic insomnia.
Insomnia is a 24-hour disorder.
It's not only sleep complaints,
these persons also feel tensed
all day.
It's not that common
that you're a very happy,
completely unanxious insomniac.
- Are you ready?
- Right.
Is there a way
to decode what goes awry
in an insomniac's brain?
On the outskirts of Amsterdam,
at the Netherlands Institute
for Neuroscience,
Eus van Someren
is trying to find out,
with the help of lifelong
insomniacs like Reiny Metz.
I drop off to sleep very easily.
But after two hours, I wake up,
and then it's difficult
to go back to sleep.
If it's one night,
well, I can manage that.
Two nights is okay,
but when it's five nights
in a row,
it's a bit much,
and then you get
very, very tired,
not only physically,
but also mentally.
It makes me anxious, or angry,
or, you know, frightened.
Reiny sleeps in Eus's lab,
wearing a high-tech E.E.G. net
that contains hundreds
of more electrodes
than you'll find
in the standard cap.
We measure sleep overnight
with a special E.E.G. net
with 256 E.E.G. channels,
and they cover all of the head.
The more electrodes he uses,
the more activity
he can record...
more clues to what's going on
in Reiny's brain.
Okay, Reiny,
we recorded your E.E.G...
Yeah.
...during your sleep.
The next morning,
he shows her the results.
So, you go into REM sleep here.
Yeah. And REM sleep
is the part of sleep
where the most vivid dreams are.
Now, what I wanted to show you
is that, you see that it's not
many seconds into REM sleep,
and then already something
is happening here.
Well, you recognize it.
I don't have to explain that
this looks different than this.
Oh, yes, certainly.
It's just maybe
two seconds or so
that it's really,
it's off, it's different.
And this is what
we call an arousal.
Yeah.
Where you exchange sleep
for something that's
really wake-like.
And this is something
that is so typical
for people like you
that sleep bad.
But you do see this in
many patients. Yeah.
Okay.
Usually, if you had
a good sleep,
if you slept on it, as we say,
things feel a bit better.
But if there is this profile,
that there is some
restlessness... Yeah.
...occurring during
REM sleep,
then, for some reason...
we try to find out...
this whole process
of feeling better the next day
doesn't work as well.
What we observed,
which was fascinating,
if we add up
all the pieces of sleep
as suggested by the E.E.G.,
many people with insomnia
have about six-and-a-half,
maybe seven hours of sleep,
but this is not
how these people experience it.
Maybe they just experience
large parts of the night
really as ongoing rumination,
worrying, thinking.
So, it may not feel
like a good night of sleep,
but it's not the same as being
completely sleep-deprived.
So, is there a connection
between these disruptions
in REM sleep
and the anxiety
so many insomniacs feel
when they're awake?
To try to find out, Eus comes up
with an out-of-the-box idea,
based on personal experience.
Back in the 1990s,
Eus played guitar
in a popular Dutch rock band.
I remembered a few things from
being in the recording studio.
I heard my own guitar playing,
and even if it was a tiny
little bit, you know, off-tune,
it made me shiver.
Embarrassment is
a powerful emotion.
He decides to put it to a test.
A karaoke test.
We asked people
to sing along karaoke,
but they couldn't hear
themselves sing.
If you don't hear yourself well,
it's also difficult to correct
if you go out of tune.
Um, you hear that
over the headphone,
you have the headphone on...
He does the same thing
with good sleepers.
Next, Eus puts them in an fMRI.
So, in the MRI scanner,
we had them listen to
their own embarrassing singing.
As Reiny listens to her singing,
the fMRI detects activity
in a part of the brain
called the amygdala.
We have two,
one in each hemisphere.
I sometimes call the amygdala
the siren of the brain
or the alarm bell of the brain.
So, if there is something
that we should pay attention to,
because it's dangerous
or important,
then the amygdala activates.
So, they heard themselves
sing really, really out of tune.
Their amygdala
was very upset about that,
so, you know,
the alarms went off.
♪ Gloria ♪
The alarms go off for both
insomniacs and good sleepers.
This is no surprise for Eus.
But his test isn't over yet.
We ask them to stay
all night in the sleep lab,
and we did the same
the next morning.
We again put them
in the MRI scanner.
Good sleepers,
it was not that bad anymore.
A good sleeper's amygdala
calms down.
But that doesn't happen
in the insomniac.
For them, the story
was very different,
because the more REM sleep
they had,
the worse it got.
So, instead of the amygdala
becoming adapted overnight,
many people with insomnia,
the next morning,
the amygdala could even
ring much louder.
You're just loaded with distress
that you take to the next day
and the next day
and the next day.
If we could change
that restless REM sleep,
maybe this will help people
get rid of distress.
But insomniacs
aren't the only ones
to suffer
from restless REM sleep.
Researchers are also exploring
its impact
on post-traumatic
stress disorder.
PTSD is essentially
a memory-based disorder.
An individual has
one or more very stressful,
traumatic experiences,
and they become fearful
of anything
that reminds them
of that trauma.
Like the smell of a wildfire
or the deafening sounds
of combat...
traumas so powerful, they can
even haunt us when we sleep.
People with post-traumatic
stress disorder,
they're afraid to go to sleep,
or they don't sleep very well
because of the nightmares.
Once these nightmares
get established,
they often can persist
for, for decades.
In her lab at U.C.L.A.,
Gina Poe is searching for ways
to prevent these recurring
nightmares from taking shape.
One of the things
that we have to do
to study the effects
of trauma on sleep
is, we have to expose animals
to a traumatic stressor.
How you doing?
It's the least favorite
part of my job,
but there's no other way
to study it.
The rats are placed in a chamber
where they hear a tone...
Followed by a shock.
It certainly is not a strong
enough shock to cause them harm
or blister their feet
or anything,
and it only lasts one second,
but it's enough to make them
squeak and jump,
to say, "What, what was that?"
Over the next hour and a half,
the rats hear the tone
and receive the shock.
So they associate that tone
with the fear of being shocked.
Then they're taken back
to their nests
to get some Zs.
But their sleep is anything
but restful.
We have found that
the REM dream state of sleep
after a rat has
experienced a trauma
can be hyperactive.
It's kind of like REM sleep
on steroids
in the way that it is
in people with post-traumatic
stress disorder.
So Gina comes up
with a novel idea.
After the shock,
half the rats go right to sleep.
The other half are kept awake
for about six hours.
In that time,
they eat, they play,
and get a chance to calm down
before they, too,
get some shut-eye.
The next day, we bring them back
into a slightly
different environment.
So, it smells different,
it has different colors,
different lighting.
In fact, the only thing
that remains the same
is the tone that came
before the shock.
When the rat that went straight
to sleep hears the tone,
it freezes.
As soon as they hear the sound,
animals with PTSD will freeze.
But what happens to the rat
that's been allowed to calm down
before going to sleep?
Will it have the same response?
When it hears the tone,
it also freezes... at first.
But then it seems to realize
the shock isn't coming.
And it will start walking around
and sniffing
and exploring,
as rats normally do.
Because they realize they're
not going to be shocked here.
Delaying sleep after a trauma
may lessen the impact
of disturbing experiences
and even prevent the nightmares
of PTSD from taking shape...
that is, in rats.
But will it help us humans?
Gina is taking her work
outside the lab,
conducting a study
with firefighters,
asking them to delay sleep
after a traumatic event.
With firefighters,
we can ask them to do
whatever it is they do
to best relax and
calm themselves after a trauma.
For some, it might be
meditation or prayer.
For others, it might be
listening to music
that they love
or going for a run.
We're going to see
if that helps us
prevent post-traumatic
stress disorder.
I used to be asked a lot,
"Why do you sleep?
What's the function of sleep?"
But I think we should
be asking the question,
"What are the functions
of sleep?"
We spend about 20% of the night
in REM sleep.
The rest of the time,
your brain is in non-REM sleep,
part of which is spent producing
those big, slow waves.
But what are they for?
One of the first scientific
experiments to find clues
was conducted back in 1924
at Cornell University
by psychologists John Jenkins
and Karl Dallenbach.
Using a group of college
students as guinea pigs,
they found that when their
students learned something new,
they had a much better
chance of remembering it
if they slept on it.
So, they found that sleep...
rather than simply being
a dormant state
where nothing too much happens
within the brain...
sleep may be important
for memory.
But then it raised all sorts
of questions about why,
and so we've been trying
to answer the question of why
since then.
At the University of Arizona,
experimental psychologist
Rebecca Gomez,
along with grad student
Katherine Esterline,
search for the "why"
with the help of a younger
generation of students.
- Toddlers.
- Three, four, five.
- Are you ready?
- Yeah!
How does sleep help them learn
and remember new words?
Wow, a zet.
We're teaching children
novel words
for completely novel objects.
Look at these.
We use this completely
new information
so we can measure
the brain's ability
to form completely novel,
completely new memories.
Hey, a beev.
So, in essence,
we're measuring
brute-force memory.
What's this?
The kids are shown four objects
they've never seen before
that have been given nonsense
names like zet...
A zet.
- Mup...
- Cool, a mup.
- Beev...
- Hey, a beev.
And toap.
A toap.
Toap.
They get a chance
to look at the objects.
Look at these.
And even touch them.
Then, half of the toddlers
go home for their afternoon nap,
while the other half
don't nap for hours...
or perhaps not at all.
The next day, they're back.
Where's the zet?
How much do they remember?
What we found is
that the children who nap
soon after learning...
Mup.
...remember the words
about 80% of the time.
Toap.
Where's the zet?
In contrast, the kids who went
through a long period of time
before they napped...
Where's the zet?
...only remembered the words
about 30% of the time.
Where's the toap?
This?
So, you see a huge difference
between 80% of the time
and 30% of the time,
and that's the difference
the nap makes.
Where's the mup?
Right here.
Why did a nap
make all the difference?
The key lays inside a tiny organ
found deep within the brain...
the hippocampus.
We have one in each hemisphere,
and they play a critical role in
helping us learn and remember.
So, think of it this way.
I have a little filing drawer
beside my desk.
And, throughout the day,
as papers come in,
I toss them in this drawer.
It's my mail that came today,
it's some papers
that I had from a class.
That's my temporary storage.
The hippocampus is like
that short-term filing drawer,
a mishmash of information
getting squeezed in,
and there's a limited amount
of room there for that.
But at the end of the day,
I could take that information
and turn around to
my whole huge filing cabinet,
which in this case
is the cortex.
The cortex, it's bigger,
and it has a really nice
sorting mechanism.
You can sort things
by their visual components,
by their auditory components.
That memory becomes
easier to find.
So the role of slow-wave sleep
is to take that information
that's been stuffed
into the hippocampus
and help move it to
its more efficient filing system
out in the cortex.
Things that you learned
yesterday
are now transferred
to a safer storage location.
But second when you wake up
in the morning,
your hippocampus has
now been cleared out,
and you have
a refreshed capacity
for new-file acquisition
all over again.
And that brings us back
to our toddlers
and the power of the midday nap.
Why does it make
such a big difference?
Why is it so important
for toddlers
to clear out
that short-term filing drawer?
Researchers have a theory.
Young children, their brains
are still developing,
and in fact,
the hippocampus is still
in the process of developing
all across the childhood years.
So it does seem
that the hippocampus,
when it's young and immature,
such as in infancy
and early childhood,
perhaps those memories need
to be stored more frequently
or moved to the cortex
more frequently.
But that doesn't mean
naps are just for kids.
It's interesting to think
that as you get older,
you actually see napping
start to return
in a number of individuals.
And there may be
a good reason why.
Most older adults report two
frustrating things about aging...
"I can't remember things
like I used to,
and I can't sleep
like I used to."
Napping could be one way
of helping maintain memories.
There are probably multiple
different reasons
why the aging brain
simply can't learn
and remember as effectively.
And I think we're identifying
that sleep is one
of those critical ingredients.
So, this is the sleep
of an older adult.
You should start seeing
these waves slowing down
and getting higher in amplitude.
That would be
what we're looking for
for slow-wave sleep.
And so far, I'm not seeing any.
Still looking.
They're asleep, but they're not
getting the slow wave
that, in a young adult,
you might expect to see by now.
And it seems to be
that the quality
of the sleeping brain waves
that you have,
the depth of those brain waves,
and the sort of,
the size of those brain waves
accurately predicts how well
you're able to hit the save
button on those memories.
Is there a way to improve
those big, slow waves
to increase our ability
to hit that save button?
Sleep researchers are
exploring a radical idea.
One of the things
that we're most interested in
is, how can we boost and enhance
sleep quality, sleep quantity,
by using, you know,
not pharmacology, but sound.
80-year-old Marion Smith is
participating in a sleep study.
To track the quality
of her slow waves,
a single electrode is placed
on her forehead.
Marion will hear carefully timed
pulses of sound
through this headband
equipped with tiny speakers.
Well, have a good night,
I'll see you tomorrow.
Our patient, Miss Smith,
is now clearly sleeping.
She is now getting deeper sleep.
By examining the brain waves
produced by a single electrode,
Phyllis has all the information
she needs
to assess the quality
of Marion's slow waves.
These are these big, slow waves,
but there are very few of them.
And this is quite typical
of an older person
who has low-amplitude
slow waves,
and they don't occur,
like, in a train.
Next, a specially designed
computer algorithm
measures the waves
to determine the best time
to deliver a particular sound...
...the pulsing of pink noise.
And we do very brief,
like, 50 milliseconds
of this very short burst
of pink noise.
And we do it five on, five off
as long as the person
is still in deep sleep.
Think of the sound waves
produced by pink noise
giving Marion's brain waves
a little push,
like a kid on a swing
or the movement of a ball
in a balance pendulum.
And what you try to do is
sing in time
with these brain waves.
But by stimulating them,
you're trying to boost
the size of those brain waves.
It's beautiful.
This is what we want them
all to look like,
these very large,
with strong upstate waves.
Even after you stop stimulating,
you can see the increase
in these slow waves.
Phyllis is finding that
a little push goes a long way.
What we're seeing here
is not only that we can
increase the amplitude...
that means the height
of these slow waves,
which is really important...
but we can also increase
the train.
So, we could prolong
the amount of slow waves.
Which is wonderful,
because it's hopeful
that the brain,
even if you're old,
is capable of boosting
these slow waves.
Not only might boosting
slow waves improve memory,
new research is revealing
that during this stage of sleep,
the brain may be doing
some critical housekeeping.
It was discovered that the brain
is actually actively
flushing out cellular waste
while we sleep.
Just like when we visit Paris,
and we see them
clean the streets at 5:00 a.m.,
our brain, it cleans out
all the waste
during this offline period.
There could be a potential link
between sleep and
neurodegenerative diseases,
like Alzheimer's disease.
And it could all come down
to this brain-cleaning process
that happens specifically
during slow-wave sleep.
We have to do a lot more work
in this area.
It's really, right now,
the tip of the iceberg.
While researchers
explore new ways
to help us get
the sleep we need,
millions of Americans
fight the urge,
staying up way past bedtime,
lured by the trappings
of technology.
Nearly everyone sooner or later
will experience some sleep loss
in their life.
The invasion of television
into the home 50 years ago,
and now computers
and telephones,
basically, we need to shut
that stuff off.
Somewhere between infancy
and even childhood,
we in Western,
industrialized nations,
we start to abandon the notion
that sleep is useful,
and, if anything,
take the opposite approach
and believe that sleep
should be short-changed.
Back in 1964,
17-year-old Randy Gardner broke
the Guinness world record
for staying awake
11 days straight.
One of these young men holds
an unusual world record.
What is your name, please?
My name is Randy Gardner.
My name is Randy Gardner.
The experiment won him
first place
in his high school science fair
and caught the attention
of a nation.
He ended up on "To Tell
the Truth,"
you know, a TV show.
And supposedly
the most written-about story
in the world
after JFK and the Beatles.
Number Two,
how did you pass the time
when the other people
were sleeping?
Well, there were always, there
was always someone with me,
the two boys that helped me...
one would sleep,
and one would stay awake
with me.
Bruce McAllister was
one of those boys.
It wasn't the science of it
that interested the world.
The world was interested
in the drama.
The experiment moved beyond
high school science
when sleep researcher
William Dement joined the team.
And he brought
a portable E.E.G.,
which no one had ever seen
before.
They sent the E.E.Gs.
to a supercomputer,
a Cray computer in Arizona,
and that computer concluded
that his...
Parts of his brain were sleeping
while others were awake.
His brain was catnapping
in pieces.
That is how the human brain
survived this.
While Randy looked wide awake,
parts of his brain weren't...
what neuroscientists now call
a microsleep.
A microsleep is
something that may happen
after we've been awake
for a very long time,
and our brain needs sleep
so desperately
that we may fall
for a very short interval
of three to 15 seconds, just...
And we've all seen this
when our eyes shut down,
and we nod to sleep for
just a few seconds like this.
We're all very polite and sort
of pretend we don't see it,
but as we're talking to someone
and they start to fall asleep,
we notice that they're losing
muscle tone,
so they start to slump, and the
head will start to fall over,
and the eye,
the lids are coming down,
and then we'll see
the eyes roll in the head.
If you're holding a steering
wheel and driving,
you might notice that your arms
are starting to slack
a little bit on the wheel.
It only takes 200 milliseconds
when you're not paying attention
that the car is going
in the wrong direction.
When you're sleep-deprived,
your brain will fall asleep...
whether you notice or not.
That's because biology
takes the wheel.
Two different processes
drive you to sleep.
The first is
your circadian rhythm,
your biological clock.
One of the signals
that's keeping you awake
during the day
is the circadian clock.
Think of the circadian clock as
kind of an internal alarm clock.
Back in 1938,
in a landmark experiment,
sleep researcher
Nathaniel Kleitman
takes one of his students
to live in an underground cave.
They spend a month
without sunlight,
testing the power
of that internal alarm clock.
Even without light,
the clock keeps ticking.
But add light,
and the cycle can shift.
Every day, you get
a little light in the morning,
it moves your clock
in one direction.
You get a little light
in the evening,
it moves your clock
in the other direction,
so it can delay and advance.
And by doing this,
it maintains your internal clock
in synchrony with that
of your external environment.
This clock controls the release
of a key chemical
that has the power
to make you feel sleepy:
melatonin, also known
as the hormone of darkness.
Melatonin goes up at night,
and it stays up
during the entire night
until probably
the early morning hours,
and then begins its decline.
By the time that we normally
would be waking up,
melatonin levels are
very, very low.
But sleepiness isn't just
controlled by melatonin.
Another chemical,
called adenosine,
may also play a role.
Some researchers believe
it starts to build
from the moment you wake up,
and, like an hourglass,
fills with the passage of time,
gradually increasing
our need for sleep,
called "sleep pressure."
We see a very strong association
between the levels of adenosine
and being sleepy
and between the level of sleep
and reducing that adenosine.
Sleep is the perfect way to
clear adenosine from the brain
and start fresh.
Many of us are trying
to block the effects
of that adenosine every day
by our consumption of caffeine.
Caffeine binds
to these adenosine receptors,
so it kind of blocks
the effects of sleep pressure,
so that we're,
we're not feeling it.
It's still there, but we're just
not feeling the effects of it.
But drinking coffee will work
for just so long.
If you choose
not to go to sleep tonight,
and you stay up all night,
that sleep pressure
will continue to build.
And as that sleep pressure
builds,
it will impair
your thought processes,
it will impair your memory.
More than 60% of our population
may not be getting
sufficient amount of sleep,
but also sufficient quality
of sleep.
For firefighter Matt Reinhold,
who often works a 72-hour
shift...
...a good night's sleep
is hard to come by.
The alarm will go off
and the lights will come on.
It's a, it's a startlement.
You know, right off the bat,
you're woken up.
There's times where we'll run
five, six, seven,
eight calls after midnight.
I have never been
in a deep sleep
here at this firehouse.
Fatigue starts to set in.
All I want to go and do
is go lay down,
but then the alarm's
going off again
for a medical down the street.
Lack of sleep definitely
makes you more snippy,
you become more agitated,
more irritated.
The communication factor
may go out the window,
because you don't want to talk,
because you're tired,
because of what you're afraid
of what you might say.
The irritability takes a toll.
There was a study that compared
a group of participants
only allowed to sleep
for five hours a night,
and then there was another group
that were allowed to sleep
for the whole eight hours,
but were woken up
every now and then
and kept awake for an hour.
And after four days like this,
the effects on mood and anxiety
were actually much stronger
in the interrupted group.
Sleeping in fits and starts
wreaks havoc
on your entire system.
That fragmenting of sleep
is extremely destructive
for wake functioning and health.
It is almost as though
you didn't get sleep.
So, the consolidation of sleep
is easily as important
as the duration of the sleep.
Quality is as important
as quantity.
There's something
about the loss of sleep
that breaks down
your mind and your body.
If you lose sleep, you will
experience memory deficits,
and you will experience
cognitive deficits.
However, there's also
an interesting caveat to that:
losing sleep may affect
one person one way
and another person another way.
There are some individuals
which tend to be resilient
against the negative effects
of sleep loss.
One of the current focuses
of our field
is to understand
the cause of that resilience
and whether there is
a genetic component.
Could the ability
to recover from sleep loss
be determined by our genes?
In 2017, the Nobel Prize
in Physiology or Medicine
was awarded to three scientists
who discovered a group of genes
that drive
your biological clock.
There are genes
such as the clock gene,
the period gene,
the cryptochrome gene.
But the gene that intrigues
neuroscientist Ketema Paul
is called BMAL1.
For those of you that know
that clocks used to have gears,
BMAL1 is the primary gear
of the clock.
In his lab at U.C.L.A.,
Ketema is exploring
the role BMAL1 may play
in our ability to recover
from sleep loss.
To do it, he makes use
of a classic memory test.
You put a mouse
in an environment
and present two objects.
In this case, two orange blocks.
The mouse spends time
getting familiar with them.
After that, we take them out
and sleep-deprive them
for six hours.
While the mouse is kept awake,
one of the orange blocks
is replaced with a new object,
a blue cylinder.
After six hours,
the sleep-deprived mouse is
put back in the chamber.
Like humans, mice are
naturally curious...
they're drawn to new things.
So a well-rested mouse
will spend more time
exploring the new object,
the blue cylinder.
But that doesn't happen
with this sleepy mouse.
If you sleep-deprive a mouse,
and you put it
in the same environment,
it will spend
equal amounts of time
between the familiar object
and the novel object,
because its memory
of the familiar object
was impaired by the sleep loss.
It seems not to remember
the orange block.
But what happens if Ketema
repeats the memory test
with a mouse that has been
genetically modified
to express higher levels
of BMAL1?
Will this dialed-up mouse
have a better memory?
Or will the results be the same?
The mouse is now
exploring the area in which
the novel object is in.
Another approach
to the novel object.
More exploration
around the arena.
A third approach
to the novel object,
sniffing,
exploring the novel object.
So the mouse is clearly spending
more time with the novel object,
and it suggests
that the sleep deprivation
did not impair
the memory of this mouse,
which suggests
that overexpressing BMAL1
does make that mouse
resilient to sleep loss,
and it preserves its memory
after sleep deprivation.
But this is not
the only surprise,
because it turns out
BMAL1 works in mysterious ways.
So the B in BMAL1
stands for "brain,"
the M in BMAL1
stands for "muscle."
BMAL1 is a gene
that's found in the brain
and in skeletal muscle.
And the resilient mice were
ones that had BMAL1 boosted
in their muscles,
not in their brains.
The result we got
was really a surprise.
Sleep is a mental process.
And that's kind of,
as a trained neurobiologist,
how I had been looking at it
before that.
As Ketema continues
his research,
he will try to find out
how genes in skeletal muscle
could influence how we sleep
and store memories.
Hopefully this will lead
to more effective therapies
for people that are unable
to get sufficient sleep
and people that need to function
in spite
of not getting enough sleep.
Because when it comes
to not getting enough sleep,
the people hardest-hit are often
the ones we depend on the most.
Sleep deprivation
of first responders
leads to issues of increased
isolation and depression
and has enormous impacts,
not on just your psychology,
but on your physical well-being,
as well.
Former E.M.S. worker
Susan Farren
and retired firefighter
Ron Shull
are working
with first responders,
educating them on ways
to manage their sleep,
on and off the job.
We want to give you guys
some tools and some techniques
and modalities to kind of
help you sleep better.
In the last ten or 20 years,
we've discovered
that sleep is essential
for proper brain function.
It's important for our health,
for our immunity,
for our memory...
Toap.
...and for our well-being.
I think that's where the phrase
"sleep on it" comes from,
is that we wake up, and we think
differently about a problem.
We think differently about that
person that we were angry at.
We just generally
feel better about our day
if we've had
a really good night's sleep.
I think sleep's one of the
sweetest things you can get.
It's like a great meal
or seeing a good friend.
As a citizen in our society
that wants people to be safe,
the best thing I can say is,
"Don't sacrifice your sleep.
"Protect your sleep
like you protect your food,
"like you protect
your resources,
"like you protect
your environment.
It may save your life."
To order this program on DVD,
visit ShopPBS
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Episodes of "NOVA" are available
with Passport.
"NOVA" is also available
on Amazon Prime Video.
Sleep remains one of
those remarkable puzzles.
We've known the functions
of eating, drinking,
and reproducing
for thousands of years.
However, sleep
remains a mystery.
Why do some people ruminate
all night,
and other people,
they see the pillow,
they're gone?
Cutting-edge research is
now giving us a new view
inside the sleeping brain.
How can we boost and enhance
sleep quality, sleep quantity?
It's really, right now,
the tip of the iceberg.
If you've ever thought of sleep
as a waste of time,
think again.
The more we learn about sleep,
the more we realize
that we can't dismiss it.
Getting a good night's sleep
is possibly the single
most important thing
you can do every day.
"Mysteries of Sleep,"
next, on "NOVA."
Major funding for "NOVA"
is provided by the following:
one of the most enduring
mysteries in all of science.
We spend a third of our lives
asleep,
in this kind of unconscious,
unresponsive, immobile state.
I mean, we can't do
any of the things
that we think are important
for our lives, like eat,
care for our young, mate.
Why do we spend
a third of our lives
in such an unproductive
and defenseless state?
What is that thing
that sleep does
to our brain and our body
every single night
is very much an open question.
A question that has baffled
scientists for centuries.
It's like this big black hole.
We don't really understand
why is it that we sleep
and what happens in our brain
when we're asleep.
But in the last decade,
sleep researchers
have started to unravel
the mysteries of sleep,
and what they are discovering
is mind-boggling.
Many people think that when
we sleep, we are unconscious,
so the brain is
sort of shut off.
But the more we explore it,
the more it's clear
that the brain is not shut off.
In fact, we find that
the brain is just as active
when we're asleep
as when we're awake.
'S just active
in different ways.
You're not either aware
or not aware,
you're neither not conscious
or unconscious.
It's a whole spectrum.
So, what exactly is sleep?
And why do we need it?
One thing that is for certain,
when it comes to sleep,
we've got a lot of company.
What we're fast learning
is that sleep isn't a luxury;
sleep is a biological necessity.
I find it fascinating,
because every animal sleeps,
every animal
that we've studied...
from worms to jellyfish
to sea slugs.
Even the octopus, whose genome
is so different from our own,
they sleep about as much time
as we do.
Sleep is one of the most
essential elements of life,
actually.
Sleep and life evolved
hand-in-hand.
Evolution has come up
with a variety of ways
to get some shut-eye.
Some animals are vulnerable
when they sleep.
And other animals are not.
And the animals that are
vulnerable when they sleep
don't sleep very much.
If animals live in the open,
they obviously have to be alert.
And they can't sleep as deeply.
You know, if a giraffe slept
the same way a lion slept,
there wouldn't be any giraffes.
Now, on the other hand,
there are animals
like the big brown bat,
which is the champion sleeper...
sleeps 20 hours a day.
It sleeps on cave walls,
so it's pretty much
invulnerable there.
But perhaps one
of nature's most innovative
sleep solutions
is found under the sea.
One of the really cool animals
that people study
is the dolphin, which actually
has unihemispheric sleep.
Half of the brain has
a sleep-like state
and the other half has
a wake-like state,
so the animal has to have
one hemisphere awake.
In fact, if you anesthetize
dolphins, they stop breathing.
And in the fur seals, such as
the one swimming behind us,
when the right hemisphere
is asleep, the left flipper,
which is controlled
by the right hemisphere,
is inactive,
and the body's posture
is asymmetric.
So by looking at a fur seal,
you can tell
which hemisphere is asleep.
Fur seals and dolphins
aren't alone.
Human sleep is equally complex,
weird, and mysterious.
I would say my favorite animal,
in terms of how animals sleep,
are humans.
Human sleep is very broad.
Each individual has their own
personal experiences with sleep.
So, what exactly is happening
inside our brains when we sleep?
We've really entered a different
world once we're asleep.
I actually think
that the whole night
is a really magical event.
With the help of volunteers
like five-year-old Jaime Lopez,
sleep researcher Rebecca Spencer
gathers clues
to how this magical event
unfolds.
Just slip this on,
just like last time.
To study sleep, we equip Jaime
with a sleep cap...
Shake, shake, shake, shake,
shake, shake, shake.
...with an array of electrodes
to record brain activity.
- Yeah.
- There you go.
The way our brain supports
everything that it does,
from controlling our body
to regulating emotion,
having memories,
is through the electrical
activity of neurons.
These are brain cells
connected to one another
via these tiny passages
that are called synapses.
One neuron emits a neurochemical
called a neurotransmitter
to this passage,
and it's picked up
by the next neuron,
much like passing the baton
in the Olympics.
This signal,
passed from neuron to neuron,
can be picked up by the
electrodes in Jaime's cap
with one of the
most powerful tools
in a sleep researcher's
toolbox...
the E.E.G.,
the electroencephalogram.
What this screen is
showing is the recordings
from each of those electrodes
in the cap that we put on Jaime.
Right now, in wake,
for instance,
you know, you can see
the brain waves here.
The vertical lines on the chart
represent five seconds
of Jaime's sleep.
What's important is
that as you get drowsy,
those waves slow down,
and they become
what we call alpha waves.
And as the sleep gets deeper,
the waves become
slower and slower,
and in the deepest parts
of sleep,
activity's dominated
by slow waves,
these massive waves
occurring across the brain
that are like a tsunami.
It's almost
like a football stadium,
where all of the individuals
in the stadium
before the game
are all sort of speaking to
each other at different moments,
at different times.
That's what seems to happen
when you're awake.
But when you go into
the deeper stages of sleep,
all of a sudden,
the crowd starts
to synchronize its activity.
They all start to chant in time.
Thousands of neurons,
firing in unison.
That's your deep sleep.
That's when it's hard
to wake you up.
When you wake up someone
who's been in slow-wave sleep,
and we ask them what they
were thinking, they will say,
"I don't know,
I wasn't thinking anything,
"I was asleep... leave me alone,
go away,"
and they'll push you off.
But Jaime...
along with the rest of us...
doesn't stay in deep,
slow-wave sleep all night.
At a certain point,
his brain waves change.
After about 50 or 60 minutes,
your brain will start
to rise back up.
And then it will pop up and
have a short REM sleep period.
Turns out that those two types
of sleep, non-REM and REM,
will play out in a battle
for brain domination
throughout the night.
And that sort of cerebral war
is going to be won and lost
every 90 minutes.
We spend most of the night
in non-REM sleep.
The rest of the time we spend
in the mysterious stage
of REM sleep.
It's hard to investigate
REM sleep
without investigating dreams,
because more than 80% of REM
periods would include a dream.
Dreams tend to be emotional.
One idea is that we dream
to simulate potentially
negative events
so that we're prepared for them.
I had a dream,
when my daughter was very young,
that she fell
into the swimming pool...
she was near drowning.
After that, I put my daughters
into swim lessons,
and water safety has been
important to me.
It's not that we do not dream
in the other sleep stages...
we do...
but the most vivid ones
are in, in REM sleep.
REM sleep is named
for the rapid eye movements
we make when we dream.
We believe that every time
the eyes move in a dream,
it's a special moment
where we sort of switch
to the next dream scene,
if you will.
As we switch
from one dream to the next,
our brain waves are doing
something downright strange.
With REM sleep, the brain waves
look just like waves
from when you're awake.
We have this paradox
that it's a state of sleep,
but yet our brain is
in a state of activation.
But perhaps the strangest
feature of this stage of sleep
is what's happening
in your body.
During REM sleep,
our brain actually sends
the instructions
to the different muscles
to move our body
as if we were awake.
But lower down
in the brain stem,
these instructions
are disrupted.
They are not relayed
to the body,
and the body remains paralyzed.
Otherwise, if we had a dream
where we fly above the city,
we would literally
jump out of the window.
From the dreams of REM sleep,
we cycle back
into non-REM sleep,
including the deepest stage
of sleep, slow-wave.
In the first half of the night,
the majority of those cycles
are comprised
of deep, non-REM sleep.
Yet, as you push through to
the second half of the night,
now that ratio balance shifts;
and instead, the majority
of those cycles
are comprised of much more
rapid-eye-movement sleep...
dream sleep...
and a lot less
deep, non-REM sleep.
What is crazy about this is,
the pattern is
so absolutely reliable
in virtually everybody,
every night.
It speaks to a fundamental,
genetically driven program
that is essential
for being a human being.
You have to go through this.
But if every one of us
needs a night full
of both slow-wave and REM sleep,
why is it such a struggle
for so many of us
to get some shut-eye?
The search for answers
has become
a multibillion-dollar industry,
selling us everything
from sleeping pills
to ergonomic pillows.
And if they don't do the trick,
there are more than 3,000
sleep clinics nationwide,
a number that keeps on growing.
Are you up all night tossing,
turning, mind racing,
trouble getting to sleep,
trouble staying asleep?
Drew Ackerman has
created a podcast
to help the sleep-deprived
get their Zs.
The idea for the show
really sprang
from my childhood insomnia.
When I was a kid, I lost
the ability to fall asleep.
For me, it was anxiety-related.
My parents tried to help,
but because they could sleep,
I think there was,
like, this disconnect.
It's, like, "Oh, try to relax,
try to just think
about something nice,"
and I just couldn't do that.
Whatever's keeping you awake,
thoughts,
you know,
things you're thinking about...
Drew's goal is to be
as boring as possible.
I'm going to tell you all
a bedtime story.
I want you to get comfortable.
The podcast is not
straightforward,
it's full of nonsense.
I have a unique hobby,
my dog and I.
We listen to recordings
of people knocking on doors.
It gives people permission
not to listen,
or to only kind of listen.
I want no social pressure
on the listener
to pay attention to me at all.
And there's no shortage
of people
eager to tune out.
Each month,
the show gets downloaded
a little bit
over three million times.
What I'm going to do is,
I'm going to send my voice
across the deep dark night.
People that listen to the
podcast share that feeling...
I don't know if desperation
might be a strong word...
but that feeling where
you're just lying there in bed,
and you feel alone.
How many people listen
to the podcast
because they have trouble
falling asleep?
Like, if you want,
raise your hand.
Having trouble falling asleep
or staying asleep
are symptoms of the most common
sleep disorder on the planet.
Ten percent of all people suffer
from chronic insomnia.
Insomnia is a 24-hour disorder.
It's not only sleep complaints,
these persons also feel tensed
all day.
It's not that common
that you're a very happy,
completely unanxious insomniac.
- Are you ready?
- Right.
Is there a way
to decode what goes awry
in an insomniac's brain?
On the outskirts of Amsterdam,
at the Netherlands Institute
for Neuroscience,
Eus van Someren
is trying to find out,
with the help of lifelong
insomniacs like Reiny Metz.
I drop off to sleep very easily.
But after two hours, I wake up,
and then it's difficult
to go back to sleep.
If it's one night,
well, I can manage that.
Two nights is okay,
but when it's five nights
in a row,
it's a bit much,
and then you get
very, very tired,
not only physically,
but also mentally.
It makes me anxious, or angry,
or, you know, frightened.
Reiny sleeps in Eus's lab,
wearing a high-tech E.E.G. net
that contains hundreds
of more electrodes
than you'll find
in the standard cap.
We measure sleep overnight
with a special E.E.G. net
with 256 E.E.G. channels,
and they cover all of the head.
The more electrodes he uses,
the more activity
he can record...
more clues to what's going on
in Reiny's brain.
Okay, Reiny,
we recorded your E.E.G...
Yeah.
...during your sleep.
The next morning,
he shows her the results.
So, you go into REM sleep here.
Yeah. And REM sleep
is the part of sleep
where the most vivid dreams are.
Now, what I wanted to show you
is that, you see that it's not
many seconds into REM sleep,
and then already something
is happening here.
Well, you recognize it.
I don't have to explain that
this looks different than this.
Oh, yes, certainly.
It's just maybe
two seconds or so
that it's really,
it's off, it's different.
And this is what
we call an arousal.
Yeah.
Where you exchange sleep
for something that's
really wake-like.
And this is something
that is so typical
for people like you
that sleep bad.
But you do see this in
many patients. Yeah.
Okay.
Usually, if you had
a good sleep,
if you slept on it, as we say,
things feel a bit better.
But if there is this profile,
that there is some
restlessness... Yeah.
...occurring during
REM sleep,
then, for some reason...
we try to find out...
this whole process
of feeling better the next day
doesn't work as well.
What we observed,
which was fascinating,
if we add up
all the pieces of sleep
as suggested by the E.E.G.,
many people with insomnia
have about six-and-a-half,
maybe seven hours of sleep,
but this is not
how these people experience it.
Maybe they just experience
large parts of the night
really as ongoing rumination,
worrying, thinking.
So, it may not feel
like a good night of sleep,
but it's not the same as being
completely sleep-deprived.
So, is there a connection
between these disruptions
in REM sleep
and the anxiety
so many insomniacs feel
when they're awake?
To try to find out, Eus comes up
with an out-of-the-box idea,
based on personal experience.
Back in the 1990s,
Eus played guitar
in a popular Dutch rock band.
I remembered a few things from
being in the recording studio.
I heard my own guitar playing,
and even if it was a tiny
little bit, you know, off-tune,
it made me shiver.
Embarrassment is
a powerful emotion.
He decides to put it to a test.
A karaoke test.
We asked people
to sing along karaoke,
but they couldn't hear
themselves sing.
If you don't hear yourself well,
it's also difficult to correct
if you go out of tune.
Um, you hear that
over the headphone,
you have the headphone on...
He does the same thing
with good sleepers.
Next, Eus puts them in an fMRI.
So, in the MRI scanner,
we had them listen to
their own embarrassing singing.
As Reiny listens to her singing,
the fMRI detects activity
in a part of the brain
called the amygdala.
We have two,
one in each hemisphere.
I sometimes call the amygdala
the siren of the brain
or the alarm bell of the brain.
So, if there is something
that we should pay attention to,
because it's dangerous
or important,
then the amygdala activates.
So, they heard themselves
sing really, really out of tune.
Their amygdala
was very upset about that,
so, you know,
the alarms went off.
♪ Gloria ♪
The alarms go off for both
insomniacs and good sleepers.
This is no surprise for Eus.
But his test isn't over yet.
We ask them to stay
all night in the sleep lab,
and we did the same
the next morning.
We again put them
in the MRI scanner.
Good sleepers,
it was not that bad anymore.
A good sleeper's amygdala
calms down.
But that doesn't happen
in the insomniac.
For them, the story
was very different,
because the more REM sleep
they had,
the worse it got.
So, instead of the amygdala
becoming adapted overnight,
many people with insomnia,
the next morning,
the amygdala could even
ring much louder.
You're just loaded with distress
that you take to the next day
and the next day
and the next day.
If we could change
that restless REM sleep,
maybe this will help people
get rid of distress.
But insomniacs
aren't the only ones
to suffer
from restless REM sleep.
Researchers are also exploring
its impact
on post-traumatic
stress disorder.
PTSD is essentially
a memory-based disorder.
An individual has
one or more very stressful,
traumatic experiences,
and they become fearful
of anything
that reminds them
of that trauma.
Like the smell of a wildfire
or the deafening sounds
of combat...
traumas so powerful, they can
even haunt us when we sleep.
People with post-traumatic
stress disorder,
they're afraid to go to sleep,
or they don't sleep very well
because of the nightmares.
Once these nightmares
get established,
they often can persist
for, for decades.
In her lab at U.C.L.A.,
Gina Poe is searching for ways
to prevent these recurring
nightmares from taking shape.
One of the things
that we have to do
to study the effects
of trauma on sleep
is, we have to expose animals
to a traumatic stressor.
How you doing?
It's the least favorite
part of my job,
but there's no other way
to study it.
The rats are placed in a chamber
where they hear a tone...
Followed by a shock.
It certainly is not a strong
enough shock to cause them harm
or blister their feet
or anything,
and it only lasts one second,
but it's enough to make them
squeak and jump,
to say, "What, what was that?"
Over the next hour and a half,
the rats hear the tone
and receive the shock.
So they associate that tone
with the fear of being shocked.
Then they're taken back
to their nests
to get some Zs.
But their sleep is anything
but restful.
We have found that
the REM dream state of sleep
after a rat has
experienced a trauma
can be hyperactive.
It's kind of like REM sleep
on steroids
in the way that it is
in people with post-traumatic
stress disorder.
So Gina comes up
with a novel idea.
After the shock,
half the rats go right to sleep.
The other half are kept awake
for about six hours.
In that time,
they eat, they play,
and get a chance to calm down
before they, too,
get some shut-eye.
The next day, we bring them back
into a slightly
different environment.
So, it smells different,
it has different colors,
different lighting.
In fact, the only thing
that remains the same
is the tone that came
before the shock.
When the rat that went straight
to sleep hears the tone,
it freezes.
As soon as they hear the sound,
animals with PTSD will freeze.
But what happens to the rat
that's been allowed to calm down
before going to sleep?
Will it have the same response?
When it hears the tone,
it also freezes... at first.
But then it seems to realize
the shock isn't coming.
And it will start walking around
and sniffing
and exploring,
as rats normally do.
Because they realize they're
not going to be shocked here.
Delaying sleep after a trauma
may lessen the impact
of disturbing experiences
and even prevent the nightmares
of PTSD from taking shape...
that is, in rats.
But will it help us humans?
Gina is taking her work
outside the lab,
conducting a study
with firefighters,
asking them to delay sleep
after a traumatic event.
With firefighters,
we can ask them to do
whatever it is they do
to best relax and
calm themselves after a trauma.
For some, it might be
meditation or prayer.
For others, it might be
listening to music
that they love
or going for a run.
We're going to see
if that helps us
prevent post-traumatic
stress disorder.
I used to be asked a lot,
"Why do you sleep?
What's the function of sleep?"
But I think we should
be asking the question,
"What are the functions
of sleep?"
We spend about 20% of the night
in REM sleep.
The rest of the time,
your brain is in non-REM sleep,
part of which is spent producing
those big, slow waves.
But what are they for?
One of the first scientific
experiments to find clues
was conducted back in 1924
at Cornell University
by psychologists John Jenkins
and Karl Dallenbach.
Using a group of college
students as guinea pigs,
they found that when their
students learned something new,
they had a much better
chance of remembering it
if they slept on it.
So, they found that sleep...
rather than simply being
a dormant state
where nothing too much happens
within the brain...
sleep may be important
for memory.
But then it raised all sorts
of questions about why,
and so we've been trying
to answer the question of why
since then.
At the University of Arizona,
experimental psychologist
Rebecca Gomez,
along with grad student
Katherine Esterline,
search for the "why"
with the help of a younger
generation of students.
- Toddlers.
- Three, four, five.
- Are you ready?
- Yeah!
How does sleep help them learn
and remember new words?
Wow, a zet.
We're teaching children
novel words
for completely novel objects.
Look at these.
We use this completely
new information
so we can measure
the brain's ability
to form completely novel,
completely new memories.
Hey, a beev.
So, in essence,
we're measuring
brute-force memory.
What's this?
The kids are shown four objects
they've never seen before
that have been given nonsense
names like zet...
A zet.
- Mup...
- Cool, a mup.
- Beev...
- Hey, a beev.
And toap.
A toap.
Toap.
They get a chance
to look at the objects.
Look at these.
And even touch them.
Then, half of the toddlers
go home for their afternoon nap,
while the other half
don't nap for hours...
or perhaps not at all.
The next day, they're back.
Where's the zet?
How much do they remember?
What we found is
that the children who nap
soon after learning...
Mup.
...remember the words
about 80% of the time.
Toap.
Where's the zet?
In contrast, the kids who went
through a long period of time
before they napped...
Where's the zet?
...only remembered the words
about 30% of the time.
Where's the toap?
This?
So, you see a huge difference
between 80% of the time
and 30% of the time,
and that's the difference
the nap makes.
Where's the mup?
Right here.
Why did a nap
make all the difference?
The key lays inside a tiny organ
found deep within the brain...
the hippocampus.
We have one in each hemisphere,
and they play a critical role in
helping us learn and remember.
So, think of it this way.
I have a little filing drawer
beside my desk.
And, throughout the day,
as papers come in,
I toss them in this drawer.
It's my mail that came today,
it's some papers
that I had from a class.
That's my temporary storage.
The hippocampus is like
that short-term filing drawer,
a mishmash of information
getting squeezed in,
and there's a limited amount
of room there for that.
But at the end of the day,
I could take that information
and turn around to
my whole huge filing cabinet,
which in this case
is the cortex.
The cortex, it's bigger,
and it has a really nice
sorting mechanism.
You can sort things
by their visual components,
by their auditory components.
That memory becomes
easier to find.
So the role of slow-wave sleep
is to take that information
that's been stuffed
into the hippocampus
and help move it to
its more efficient filing system
out in the cortex.
Things that you learned
yesterday
are now transferred
to a safer storage location.
But second when you wake up
in the morning,
your hippocampus has
now been cleared out,
and you have
a refreshed capacity
for new-file acquisition
all over again.
And that brings us back
to our toddlers
and the power of the midday nap.
Why does it make
such a big difference?
Why is it so important
for toddlers
to clear out
that short-term filing drawer?
Researchers have a theory.
Young children, their brains
are still developing,
and in fact,
the hippocampus is still
in the process of developing
all across the childhood years.
So it does seem
that the hippocampus,
when it's young and immature,
such as in infancy
and early childhood,
perhaps those memories need
to be stored more frequently
or moved to the cortex
more frequently.
But that doesn't mean
naps are just for kids.
It's interesting to think
that as you get older,
you actually see napping
start to return
in a number of individuals.
And there may be
a good reason why.
Most older adults report two
frustrating things about aging...
"I can't remember things
like I used to,
and I can't sleep
like I used to."
Napping could be one way
of helping maintain memories.
There are probably multiple
different reasons
why the aging brain
simply can't learn
and remember as effectively.
And I think we're identifying
that sleep is one
of those critical ingredients.
So, this is the sleep
of an older adult.
You should start seeing
these waves slowing down
and getting higher in amplitude.
That would be
what we're looking for
for slow-wave sleep.
And so far, I'm not seeing any.
Still looking.
They're asleep, but they're not
getting the slow wave
that, in a young adult,
you might expect to see by now.
And it seems to be
that the quality
of the sleeping brain waves
that you have,
the depth of those brain waves,
and the sort of,
the size of those brain waves
accurately predicts how well
you're able to hit the save
button on those memories.
Is there a way to improve
those big, slow waves
to increase our ability
to hit that save button?
Sleep researchers are
exploring a radical idea.
One of the things
that we're most interested in
is, how can we boost and enhance
sleep quality, sleep quantity,
by using, you know,
not pharmacology, but sound.
80-year-old Marion Smith is
participating in a sleep study.
To track the quality
of her slow waves,
a single electrode is placed
on her forehead.
Marion will hear carefully timed
pulses of sound
through this headband
equipped with tiny speakers.
Well, have a good night,
I'll see you tomorrow.
Our patient, Miss Smith,
is now clearly sleeping.
She is now getting deeper sleep.
By examining the brain waves
produced by a single electrode,
Phyllis has all the information
she needs
to assess the quality
of Marion's slow waves.
These are these big, slow waves,
but there are very few of them.
And this is quite typical
of an older person
who has low-amplitude
slow waves,
and they don't occur,
like, in a train.
Next, a specially designed
computer algorithm
measures the waves
to determine the best time
to deliver a particular sound...
...the pulsing of pink noise.
And we do very brief,
like, 50 milliseconds
of this very short burst
of pink noise.
And we do it five on, five off
as long as the person
is still in deep sleep.
Think of the sound waves
produced by pink noise
giving Marion's brain waves
a little push,
like a kid on a swing
or the movement of a ball
in a balance pendulum.
And what you try to do is
sing in time
with these brain waves.
But by stimulating them,
you're trying to boost
the size of those brain waves.
It's beautiful.
This is what we want them
all to look like,
these very large,
with strong upstate waves.
Even after you stop stimulating,
you can see the increase
in these slow waves.
Phyllis is finding that
a little push goes a long way.
What we're seeing here
is not only that we can
increase the amplitude...
that means the height
of these slow waves,
which is really important...
but we can also increase
the train.
So, we could prolong
the amount of slow waves.
Which is wonderful,
because it's hopeful
that the brain,
even if you're old,
is capable of boosting
these slow waves.
Not only might boosting
slow waves improve memory,
new research is revealing
that during this stage of sleep,
the brain may be doing
some critical housekeeping.
It was discovered that the brain
is actually actively
flushing out cellular waste
while we sleep.
Just like when we visit Paris,
and we see them
clean the streets at 5:00 a.m.,
our brain, it cleans out
all the waste
during this offline period.
There could be a potential link
between sleep and
neurodegenerative diseases,
like Alzheimer's disease.
And it could all come down
to this brain-cleaning process
that happens specifically
during slow-wave sleep.
We have to do a lot more work
in this area.
It's really, right now,
the tip of the iceberg.
While researchers
explore new ways
to help us get
the sleep we need,
millions of Americans
fight the urge,
staying up way past bedtime,
lured by the trappings
of technology.
Nearly everyone sooner or later
will experience some sleep loss
in their life.
The invasion of television
into the home 50 years ago,
and now computers
and telephones,
basically, we need to shut
that stuff off.
Somewhere between infancy
and even childhood,
we in Western,
industrialized nations,
we start to abandon the notion
that sleep is useful,
and, if anything,
take the opposite approach
and believe that sleep
should be short-changed.
Back in 1964,
17-year-old Randy Gardner broke
the Guinness world record
for staying awake
11 days straight.
One of these young men holds
an unusual world record.
What is your name, please?
My name is Randy Gardner.
My name is Randy Gardner.
The experiment won him
first place
in his high school science fair
and caught the attention
of a nation.
He ended up on "To Tell
the Truth,"
you know, a TV show.
And supposedly
the most written-about story
in the world
after JFK and the Beatles.
Number Two,
how did you pass the time
when the other people
were sleeping?
Well, there were always, there
was always someone with me,
the two boys that helped me...
one would sleep,
and one would stay awake
with me.
Bruce McAllister was
one of those boys.
It wasn't the science of it
that interested the world.
The world was interested
in the drama.
The experiment moved beyond
high school science
when sleep researcher
William Dement joined the team.
And he brought
a portable E.E.G.,
which no one had ever seen
before.
They sent the E.E.Gs.
to a supercomputer,
a Cray computer in Arizona,
and that computer concluded
that his...
Parts of his brain were sleeping
while others were awake.
His brain was catnapping
in pieces.
That is how the human brain
survived this.
While Randy looked wide awake,
parts of his brain weren't...
what neuroscientists now call
a microsleep.
A microsleep is
something that may happen
after we've been awake
for a very long time,
and our brain needs sleep
so desperately
that we may fall
for a very short interval
of three to 15 seconds, just...
And we've all seen this
when our eyes shut down,
and we nod to sleep for
just a few seconds like this.
We're all very polite and sort
of pretend we don't see it,
but as we're talking to someone
and they start to fall asleep,
we notice that they're losing
muscle tone,
so they start to slump, and the
head will start to fall over,
and the eye,
the lids are coming down,
and then we'll see
the eyes roll in the head.
If you're holding a steering
wheel and driving,
you might notice that your arms
are starting to slack
a little bit on the wheel.
It only takes 200 milliseconds
when you're not paying attention
that the car is going
in the wrong direction.
When you're sleep-deprived,
your brain will fall asleep...
whether you notice or not.
That's because biology
takes the wheel.
Two different processes
drive you to sleep.
The first is
your circadian rhythm,
your biological clock.
One of the signals
that's keeping you awake
during the day
is the circadian clock.
Think of the circadian clock as
kind of an internal alarm clock.
Back in 1938,
in a landmark experiment,
sleep researcher
Nathaniel Kleitman
takes one of his students
to live in an underground cave.
They spend a month
without sunlight,
testing the power
of that internal alarm clock.
Even without light,
the clock keeps ticking.
But add light,
and the cycle can shift.
Every day, you get
a little light in the morning,
it moves your clock
in one direction.
You get a little light
in the evening,
it moves your clock
in the other direction,
so it can delay and advance.
And by doing this,
it maintains your internal clock
in synchrony with that
of your external environment.
This clock controls the release
of a key chemical
that has the power
to make you feel sleepy:
melatonin, also known
as the hormone of darkness.
Melatonin goes up at night,
and it stays up
during the entire night
until probably
the early morning hours,
and then begins its decline.
By the time that we normally
would be waking up,
melatonin levels are
very, very low.
But sleepiness isn't just
controlled by melatonin.
Another chemical,
called adenosine,
may also play a role.
Some researchers believe
it starts to build
from the moment you wake up,
and, like an hourglass,
fills with the passage of time,
gradually increasing
our need for sleep,
called "sleep pressure."
We see a very strong association
between the levels of adenosine
and being sleepy
and between the level of sleep
and reducing that adenosine.
Sleep is the perfect way to
clear adenosine from the brain
and start fresh.
Many of us are trying
to block the effects
of that adenosine every day
by our consumption of caffeine.
Caffeine binds
to these adenosine receptors,
so it kind of blocks
the effects of sleep pressure,
so that we're,
we're not feeling it.
It's still there, but we're just
not feeling the effects of it.
But drinking coffee will work
for just so long.
If you choose
not to go to sleep tonight,
and you stay up all night,
that sleep pressure
will continue to build.
And as that sleep pressure
builds,
it will impair
your thought processes,
it will impair your memory.
More than 60% of our population
may not be getting
sufficient amount of sleep,
but also sufficient quality
of sleep.
For firefighter Matt Reinhold,
who often works a 72-hour
shift...
...a good night's sleep
is hard to come by.
The alarm will go off
and the lights will come on.
It's a, it's a startlement.
You know, right off the bat,
you're woken up.
There's times where we'll run
five, six, seven,
eight calls after midnight.
I have never been
in a deep sleep
here at this firehouse.
Fatigue starts to set in.
All I want to go and do
is go lay down,
but then the alarm's
going off again
for a medical down the street.
Lack of sleep definitely
makes you more snippy,
you become more agitated,
more irritated.
The communication factor
may go out the window,
because you don't want to talk,
because you're tired,
because of what you're afraid
of what you might say.
The irritability takes a toll.
There was a study that compared
a group of participants
only allowed to sleep
for five hours a night,
and then there was another group
that were allowed to sleep
for the whole eight hours,
but were woken up
every now and then
and kept awake for an hour.
And after four days like this,
the effects on mood and anxiety
were actually much stronger
in the interrupted group.
Sleeping in fits and starts
wreaks havoc
on your entire system.
That fragmenting of sleep
is extremely destructive
for wake functioning and health.
It is almost as though
you didn't get sleep.
So, the consolidation of sleep
is easily as important
as the duration of the sleep.
Quality is as important
as quantity.
There's something
about the loss of sleep
that breaks down
your mind and your body.
If you lose sleep, you will
experience memory deficits,
and you will experience
cognitive deficits.
However, there's also
an interesting caveat to that:
losing sleep may affect
one person one way
and another person another way.
There are some individuals
which tend to be resilient
against the negative effects
of sleep loss.
One of the current focuses
of our field
is to understand
the cause of that resilience
and whether there is
a genetic component.
Could the ability
to recover from sleep loss
be determined by our genes?
In 2017, the Nobel Prize
in Physiology or Medicine
was awarded to three scientists
who discovered a group of genes
that drive
your biological clock.
There are genes
such as the clock gene,
the period gene,
the cryptochrome gene.
But the gene that intrigues
neuroscientist Ketema Paul
is called BMAL1.
For those of you that know
that clocks used to have gears,
BMAL1 is the primary gear
of the clock.
In his lab at U.C.L.A.,
Ketema is exploring
the role BMAL1 may play
in our ability to recover
from sleep loss.
To do it, he makes use
of a classic memory test.
You put a mouse
in an environment
and present two objects.
In this case, two orange blocks.
The mouse spends time
getting familiar with them.
After that, we take them out
and sleep-deprive them
for six hours.
While the mouse is kept awake,
one of the orange blocks
is replaced with a new object,
a blue cylinder.
After six hours,
the sleep-deprived mouse is
put back in the chamber.
Like humans, mice are
naturally curious...
they're drawn to new things.
So a well-rested mouse
will spend more time
exploring the new object,
the blue cylinder.
But that doesn't happen
with this sleepy mouse.
If you sleep-deprive a mouse,
and you put it
in the same environment,
it will spend
equal amounts of time
between the familiar object
and the novel object,
because its memory
of the familiar object
was impaired by the sleep loss.
It seems not to remember
the orange block.
But what happens if Ketema
repeats the memory test
with a mouse that has been
genetically modified
to express higher levels
of BMAL1?
Will this dialed-up mouse
have a better memory?
Or will the results be the same?
The mouse is now
exploring the area in which
the novel object is in.
Another approach
to the novel object.
More exploration
around the arena.
A third approach
to the novel object,
sniffing,
exploring the novel object.
So the mouse is clearly spending
more time with the novel object,
and it suggests
that the sleep deprivation
did not impair
the memory of this mouse,
which suggests
that overexpressing BMAL1
does make that mouse
resilient to sleep loss,
and it preserves its memory
after sleep deprivation.
But this is not
the only surprise,
because it turns out
BMAL1 works in mysterious ways.
So the B in BMAL1
stands for "brain,"
the M in BMAL1
stands for "muscle."
BMAL1 is a gene
that's found in the brain
and in skeletal muscle.
And the resilient mice were
ones that had BMAL1 boosted
in their muscles,
not in their brains.
The result we got
was really a surprise.
Sleep is a mental process.
And that's kind of,
as a trained neurobiologist,
how I had been looking at it
before that.
As Ketema continues
his research,
he will try to find out
how genes in skeletal muscle
could influence how we sleep
and store memories.
Hopefully this will lead
to more effective therapies
for people that are unable
to get sufficient sleep
and people that need to function
in spite
of not getting enough sleep.
Because when it comes
to not getting enough sleep,
the people hardest-hit are often
the ones we depend on the most.
Sleep deprivation
of first responders
leads to issues of increased
isolation and depression
and has enormous impacts,
not on just your psychology,
but on your physical well-being,
as well.
Former E.M.S. worker
Susan Farren
and retired firefighter
Ron Shull
are working
with first responders,
educating them on ways
to manage their sleep,
on and off the job.
We want to give you guys
some tools and some techniques
and modalities to kind of
help you sleep better.
In the last ten or 20 years,
we've discovered
that sleep is essential
for proper brain function.
It's important for our health,
for our immunity,
for our memory...
Toap.
...and for our well-being.
I think that's where the phrase
"sleep on it" comes from,
is that we wake up, and we think
differently about a problem.
We think differently about that
person that we were angry at.
We just generally
feel better about our day
if we've had
a really good night's sleep.
I think sleep's one of the
sweetest things you can get.
It's like a great meal
or seeing a good friend.
As a citizen in our society
that wants people to be safe,
the best thing I can say is,
"Don't sacrifice your sleep.
"Protect your sleep
like you protect your food,
"like you protect
your resources,
"like you protect
your environment.
It may save your life."
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