Thank you very much.
00:00
Well, I would like
to start with testicles.
00:02
Men who sleep five hours a night
00:09
have significantly smaller testicles
than those who sleep seven hours or more.
00:11
In addition, men who routinely sleep
just four to five hours a night
00:20
will have a level of testosterone
00:25
which is that of someone
10 years their senior.
00:27
So a lack of sleep
will age a man by a decade
00:33
in terms of that critical
aspect of wellness.
00:36
And we see equivalent impairments
in female reproductive health
00:41
caused by a lack of sleep.
00:46
This is the best news
that I have for you today.
00:51
From this point, it may only get worse.
00:56
Not only will I tell you
about the wonderfully good things
00:58
that happen when you get sleep,
01:01
but the alarmingly bad things
that happen when you don't get enough,
01:03
both for your brain and for your body.
01:08
Let me start with the brain
01:11
and the functions of learning and memory,
01:13
because what we've discovered
over the past 10 or so years
01:16
is that you need sleep after learning
01:20
to essentially hit the save button
on those new memories
01:23
so that you don't forget.
01:26
But recently, we discovered
that you also need sleep before learning
01:28
to actually prepare your brain,
01:34
almost like a dry sponge
01:37
ready to initially soak up
new information.
01:39
And without sleep,
the memory circuits of the brain
01:43
essentially become
waterlogged, as it were,
01:46
and you can't absorb new memories.
01:49
So let me show you the data.
01:52
Here in this study, we decided
to test the hypothesis
01:54
that pulling the all-nighter
was a good idea.
01:58
So we took a group of individuals
02:02
and we assigned them
to one of two experimental groups:
02:04
a sleep group
and a sleep deprivation group.
02:08
Now the sleep group, they're going to get
a full eight hours of slumber,
02:11
but the deprivation group,
we're going to keep them awake
02:16
in the laboratory, under full supervision.
02:18
There's no naps or caffeine, by the way,
so it's miserable for everyone involved.
02:21
And then the next day,
02:26
we're going to place those participants
inside an MRI scanner
02:28
and we're going to have them
try and learn a whole list of new facts
02:32
as we're taking snapshots
of brain activity.
02:36
And then we're going to test them
02:39
to see how effective
that learning has been.
02:41
And that's what you're looking at
here on the vertical axis.
02:44
And when you put
those two groups head to head,
02:48
what you find is a quite significant,
40-percent deficit
02:51
in the ability of the brain
to make new memories without sleep.
02:56
I think this should be concerning,
03:01
considering what we know
is happening to sleep
03:02
in our education populations right now.
03:05
In fact, to put that in context,
03:08
it would be the difference
in a child acing an exam
03:10
versus failing it miserably -- 40 percent.
03:13
And we've gone on to discover
what goes wrong within your brain
03:18
to produce these types
of learning disabilities.
03:22
And there's a structure that sits
03:26
on the left and the right side
of your brain, called the hippocampus.
03:28
And you can think of the hippocampus
03:32
almost like the informational
inbox of your brain.
03:34
It's very good at receiving
new memory files
03:38
and then holding on to them.
03:41
And when you look at this structure
03:44
in those people who'd had
a full night of sleep,
03:46
we saw lots of healthy
learning-related activity.
03:49
Yet in those people
who were sleep-deprived,
03:54
we actually couldn't find
any significant signal whatsoever.
03:57
So it's almost as though sleep deprivation
had shut down your memory inbox,
04:02
and any new incoming files --
they were just being bounced.
04:07
You couldn't effectively
commit new experiences to memory.
04:11
So that's the bad that can happen
if I were to take sleep away from you,
04:18
but let me just come back
to that control group for a second.
04:22
Do you remember those folks
that got a full eight hours of sleep?
04:26
Well, we can ask
a very different question:
04:30
What is it about the physiological
quality of your sleep
04:32
that restores and enhances
your memory and learning ability
04:38
each and every day?
04:41
And by placing electrodes
all over the head,
04:43
what we've discovered
is that there are big, powerful brainwaves
04:46
that happen during
the very deepest stages of sleep
04:51
that have riding on top of them
04:54
these spectacular bursts
of electrical activity
04:57
that we call sleep spindles.
05:00
And it's the combined quality
of these deep-sleep brainwaves
05:03
that acts like a file-transfer
mechanism at night,
05:07
shifting memories from a short-term
vulnerable reservoir
05:11
to a more permanent long-term
storage site within the brain,
05:16
and therefore protecting them,
making them safe.
05:20
And it is important that we understand
05:25
what during sleep actually transacts
these memory benefits,
05:27
because there are real medical
and societal implications.
05:32
And let me just tell you about one area
05:36
that we've moved this work
out into, clinically,
05:38
which is the context of aging
and dementia.
05:42
Because it's of course no secret
that, as we get older,
05:46
our learning and memory abilities
begin to fade and decline.
05:50
But what we've also discovered
05:55
is that a physiological signature of aging
is that your sleep gets worse,
05:56
especially that deep quality of sleep
that I was just discussing.
06:03
And only last year,
we finally published evidence
06:08
that these two things,
they're not simply co-occurring,
06:11
they are significantly interrelated.
06:14
And it suggests
that the disruption of deep sleep
06:18
is an underappreciated factor
06:22
that is contributing
to cognitive decline or memory decline
06:24
in aging, and most recently
we've discovered,
06:28
in Alzheimer's disease as well.
06:31
Now, I know this is remarkably
depressing news.
06:36
It's in the mail. It's coming at you.
06:40
But there's a potential
silver lining here.
06:42
Unlike many of the other factors
that we know are associated with aging,
06:45
for example changes
in the physical structure of the brain,
06:50
that's fiendishly difficult to treat.
06:54
But that sleep is a missing piece
in the explanatory puzzle
06:57
of aging and Alzheimer's is exciting
07:01
because we may be able
to do something about it.
07:04
And one way that we are
approaching this at my sleep center
07:08
is not by using
sleeping pills, by the way.
07:12
Unfortunately, they are blunt instruments
that do not produce naturalistic sleep.
07:15
Instead, we're actually developing
a method based on this.
07:21
It's called direct current
brain stimulation.
07:24
You insert a small amount
of voltage into the brain,
07:28
so small you typically don't feel it,
07:31
but it has a measurable impact.
07:33
Now if you apply this stimulation
during sleep in young, healthy adults,
07:36
as if you're sort of singing in time
with those deep-sleep brainwaves,
07:43
not only can you amplify
the size of those deep-sleep brainwaves,
07:47
but in doing so, we can almost
double the amount of memory benefit
07:52
that you get from sleep.
07:57
The question now
is whether we can translate
07:59
this same affordable,
potentially portable piece of technology
08:01
into older adults and those with dementia.
08:06
Can we restore back
some healthy quality of deep sleep,
08:10
and in doing so, can we salvage
aspects of their learning
08:15
and memory function?
08:19
That is my real hope now.
08:21
That's one of our moon-shot
goals, as it were.
08:24
So that's an example
of sleep for your brain,
08:29
but sleep is just
as essential for your body.
08:32
We've already spoken about sleep loss
and your reproductive system.
08:37
Or I could tell you about sleep loss
and your cardiovascular system,
08:41
and that all it takes is one hour.
08:46
Because there is a global experiment
performed on 1.6 billion people
08:49
across 70 countries twice a year,
08:55
and it's called daylight saving time.
08:59
Now, in the spring,
when we lose one hour of sleep,
09:02
we see a subsequent 24-percent increase
in heart attacks that following day.
09:06
In the autumn,
when we gain an hour of sleep,
09:14
we see a 21-percent
reduction in heart attacks.
09:18
Isn't that incredible?
09:23
And you see exactly the same profile
for car crashes, road traffic accidents,
09:26
even suicide rates.
09:32
But as a deeper dive,
I want to focus on this:
09:36
sleep loss and your immune system.
09:39
And here, I'll introduce these delightful
blue elements in the image.
09:43
They are called natural killer cells,
09:47
and you can think of natural killer cells
almost like the secret service agents
09:51
of your immune system.
09:56
They are very good at identifying
dangerous, unwanted elements
09:57
and eliminating them.
10:02
In fact, what they're doing here
is destroying a cancerous tumor mass.
10:05
So what you wish for
is a virile set of these immune assassins
10:10
and tragically, that's what you don't have
if you're not sleeping enough.
10:18
So here in this experiment,
10:23
you're not going to have your sleep
deprived for an entire night,
10:25
you're simply going to have your sleep
restricted to four hours
10:29
for one single night,
10:32
and then we're going to look to see
what's the percent reduction
10:34
in immune cell activity that you suffer.
10:37
And it's not small -- it's not 10 percent,
10:40
it's not 20 percent.
10:43
There was a 70-percent drop
in natural killer cell activity.
10:45
That's a concerning state
of immune deficiency,
10:51
and you can perhaps understand
why we're now finding
10:57
significant links between
short sleep duration
11:00
and your risk for the development
of numerous forms of cancer.
11:04
Currently, that list includes
cancer of the bowel,
11:09
cancer of the prostate
and cancer of the breast.
11:12
In fact, the link between a lack of sleep
and cancer is now so strong
11:17
that the World Health Organization
11:23
has classified any form
of nighttime shift work
11:25
as a probable carcinogen,
11:29
because of a disruption
of your sleep-wake rhythms.
11:33
So you may have heard of that old maxim
11:37
that you can sleep when you're dead.
11:40
Well, I'm being quite serious now --
11:42
it is mortally unwise advice.
11:44
We know this from epidemiological studies
across millions of individuals.
11:48
There's a simple truth:
11:53
the shorter your sleep,
the shorter your life.
11:55
Short sleep predicts all-cause mortality.
11:58
And if increasing your risk
for the development of cancer
12:04
or even Alzheimer's disease
12:09
were not sufficiently disquieting,
12:11
we have since discovered
that a lack of sleep will even erode
12:15
the very fabric of biological life itself,
12:19
your DNA genetic code.
12:24
So here in this study,
they took a group of healthy adults
12:28
and they limited them
to six hours of sleep a night
12:31
and then they measured the change
in their gene activity profile
12:37
relative to when those same individuals
12:41
were getting a full eight hours
of sleep a night.
12:43
And there were two critical findings.
12:47
First, a sizable and significant 711 genes
12:50
were distorted in their activity,
12:55
caused by a lack of sleep.
12:57
The second result
was that about half of those genes
12:59
were actually increased in their activity.
13:03
The other half were decreased.
13:05
Now those genes that were switched off
by a lack of sleep
13:08
were genes associated
with your immune system,
13:11
so once again, you can see
that immune deficiency.
13:15
In contrast, those genes
that were actually upregulated
13:19
or increased by way of a lack of sleep,
13:22
were genes associated
with the promotion of tumors,
13:24
genes associated with long-term
chronic inflammation within the body,
13:28
and genes associated with stress,
13:33
and, as a consequence,
cardiovascular disease.
13:36
There is simply no aspect of your wellness
13:41
that can retreat at the sign
of sleep deprivation
13:44
and get away unscathed.
13:48
It's rather like a broken
water pipe in your home.
13:50
Sleep loss will leak down
into every nook and cranny
13:53
of your physiology,
13:57
even tampering with
the very DNA nucleic alphabet
14:00
that spells out
your daily health narrative.
14:03
And at this point, you may be thinking,
14:09
"Oh my goodness,
how do I start to get better sleep?
14:12
What are you tips for good sleep?"
14:15
Well, beyond avoiding
the damaging and harmful impact
14:18
of alcohol and caffeine on sleep,
14:22
and if you're struggling
with sleep at night,
14:25
avoiding naps during the day,
14:27
I have two pieces of advice for you.
14:30
The first is regularity.
14:33
Go to bed at the same time,
wake up at the same time,
14:35
no matter whether
it's the weekday or the weekend.
14:39
Regularity is king,
14:42
and it will anchor your sleep
14:45
and improve the quantity
and the quality of that sleep.
14:47
The second is keep it cool.
14:52
Your body needs to drop
its core temperature
14:56
by about two to three degrees
Fahrenheit to initiate sleep
14:58
and then to stay asleep,
15:02
and it's the reason
you will always find it easier
15:04
to fall asleep in a room that's too cold
15:07
So aim for a bedroom temperature
of around 65 degrees,
15:11
or about 18 degrees Celsius.
15:15
That's going to be optimal
for the sleep of most people.
15:17
And then finally,
in taking a step back, then,
15:22
what is the mission-critical
statement here?
15:25
Well, I think it may be this:
15:30
sleep, unfortunately,
is not an optional lifestyle luxury.
15:32
Sleep is a nonnegotiable
biological necessity.
15:39
It is your life-support system,
15:44
and it is Mother Nature's
best effort yet at immortality.
15:48
And the decimation of sleep
throughout industrialized nations
15:54
is having a catastrophic impact
on our health, our wellness,
15:59
even the safety and the education
of our children.
16:04
It's a silent sleep loss epidemic,
16:08
and it's fast becoming one of the greatest
public health challenges
16:11
that we face in the 21st century.
16:14
I believe it is now time for us
to reclaim our right
16:20
to a full night of sleep,
16:25
and without embarrassment
16:27
or that unfortunate stigma of laziness.
16:30
And in doing so, we can be reunited
with the most powerful elixir of life,
16:34
the Swiss Army knife
of health, as it were.
16:42
And with that soapbox rant over,
16:46
I will simply say, good night, good luck,
16:49
I do hope you sleep well.
16:54
Thank you very much indeed.
16:56
David Biello: No, no, no.
Stay there for a second.
17:08
Good job not running away, though.
I appreciate that.
17:10
So that was terrifying.
17:13
Matt Walker: You're welcome.
DB: Yes, thank you, thank you.
17:14
Since we can't catch up on sleep,
what are we supposed to do?
17:18
What do we do when we're, like,
tossing and turning in bed late at night
17:23
or doing shift work or whatever else?
17:27
MW: So you're right,
we can't catch up on sleep.
17:30
Sleep is not like the bank.
17:32
You can't accumulate a debt
17:33
and then hope to pay it off
at a later point in time.
17:35
I should also note the reason
that it's so catastrophic
17:38
and that our health
deteriorates so quickly,
17:41
first, it's because human beings
are the only species
17:44
that deliberately deprive
themselves of sleep
17:47
for no apparent reason.
17:50
DB: Because we're smart.
17:52
MW: And I make that point
because it means that Mother Nature,
17:53
throughout the course of evolution,
17:58
has never had to face the challenge
of this thing called sleep deprivation.
18:00
So she's never developed a safety net,
18:05
and that's why when you undersleep,
18:08
things just sort of implode so quickly,
both within the brain and the body.
18:10
So you just have to prioritize.
18:15
DB: OK, but tossing and turning in bed,
18:18
MW: So if you are staying in bed
awake for too long,
18:22
you should get out of bed
and go to a different room
18:27
and do something different.
18:30
The reason is because your brain
will very quickly associate your bedroom
18:32
with the place of wakefulness,
18:36
and you need to break that association.
18:38
So only return to bed when you are sleepy,
18:41
and that way you will relearn
the association that you once had,
18:44
which is your bed is the place of sleep.
18:47
So the analogy would be,
18:50
you'd never sit at the dinner table,
waiting to get hungry,
18:52
so why would you lie in bed,
waiting to get sleepy?
18:55
DB: Well, thank you for that wake-up call.
18:59
MW: You're very welcome.
Thank you very much.
19:02