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Sleep Is Your Superpower | Matt Walker | TED — Transcript

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0:00Thank you very much.
0:02Well, I would like to start with testicles.
0:06(Laughter)
0:09Men who sleep five hours a night
0:11have significantly smaller testicles than those who sleep seven hours or more.
0:17(Laughter)
0:20In addition, men who routinely sleep just four to five hours a night
0:25will have a level of testosterone
0:27which is that of someone 10 years their senior.
0:33So a lack of sleep will age a man by a decade
0:36in terms of that critical aspect of wellness.
0:41And we see equivalent impairments in female reproductive health
0:46caused by a lack of sleep.
0:51This is the best news that I have for you today.
0:53(Laughter)
0:56From this point, it may only get worse.
0:58Not only will I tell you about the wonderfully good things
1:01that happen when you get sleep,
1:03but the alarmingly bad things that happen when you don't get enough,
1:08both for your brain and for your body.
1:11Let me start with the brain
1:13and the functions of learning and memory,
1:16because what we've discovered over the past 10 or so years
1:20is that you need sleep after learning
1:23to essentially hit the save button on those new memories
1:26so that you don't forget.
1:28But recently, we discovered that you also need sleep before learning
1:34to actually prepare your brain,
1:37almost like a dry sponge
1:39ready to initially soak up new information.
1:43And without sleep, the memory circuits of the brain
1:46essentially become waterlogged, as it were,
1:49and you can't absorb new memories.
1:52So let me show you the data.
1:54Here in this study, we decided to test the hypothesis
1:58that pulling the all-nighter was a good idea.
2:02So we took a group of individuals
2:04and we assigned them to one of two experimental groups:
2:08a sleep group and a sleep deprivation group.
2:11Now the sleep group, they're going to get a full eight hours of slumber,
2:16but the deprivation group, we're going to keep them awake
2:19in the laboratory, under full supervision.
2:21There's no naps or caffeine, by the way, so it's miserable for everyone involved.
2:26And then the next day,
2:28we're going to place those participants inside an MRI scanner
2:32and we're going to have them try and learn a whole list of new facts
2:36as we're taking snapshots of brain activity.
2:39And then we're going to test them
2:41to see how effective that learning has been.
2:44And that's what you're looking at here on the vertical axis.
2:48And when you put those two groups head to head,
2:51what you find is a quite significant, 40-percent deficit
2:56in the ability of the brain to make new memories without sleep.
3:01I think this should be concerning,
3:02considering what we know is happening to sleep
3:05in our education populations right now.
3:08In fact, to put that in context,
3:10it would be the difference in a child acing an exam
3:13versus failing it miserably -- 40 percent.
3:18And we've gone on to discover what goes wrong within your brain
3:22to produce these types of learning disabilities.
3:26And there's a structure that sits
3:28on the left and the right side of your brain, called the hippocampus.
3:33And you can think of the hippocampus
3:34almost like the informational inbox of your brain.
3:38It's very good at receiving new memory files
3:41and then holding on to them.
3:44And when you look at this structure
3:46in those people who'd had a full night of sleep,
3:49we saw lots of healthy learning-related activity.
3:54Yet in those people who were sleep-deprived,
3:57we actually couldn't find any significant signal whatsoever.
4:02So it's almost as though sleep deprivation had shut down your memory inbox,
4:07and any new incoming files -- they were just being bounced.
4:11You couldn't effectively commit new experiences to memory.
4:18So that's the bad that can happen if I were to take sleep away from you,
4:22but let me just come back to that control group for a second.
4:26Do you remember those folks that got a full eight hours of sleep?
4:30Well, we can ask a very different question:
4:32What is it about the physiological quality of your sleep
4:36when you do get it
4:38that restores and enhances your memory and learning ability
4:41each and every day?
4:44And by placing electrodes all over the head,
4:47what we've discovered is that there are big, powerful brainwaves
4:51that happen during the very deepest stages of sleep
4:54that have riding on top of them
4:57these spectacular bursts of electrical activity
5:00that we call sleep spindles.
5:03And it's the combined quality of these deep-sleep brainwaves
5:07that acts like a file-transfer mechanism at night,
5:12shifting memories from a short-term vulnerable reservoir
5:16to a more permanent long-term storage site within the brain,
5:20and therefore protecting them, making them safe.
5:25And it is important that we understand
5:27what during sleep actually transacts these memory benefits,
5:32because there are real medical and societal implications.
5:36And let me just tell you about one area
5:38that we've moved this work out into, clinically,
5:42which is the context of aging and dementia.
5:46Because it's of course no secret that, as we get older,
5:50our learning and memory abilities begin to fade and decline.
5:55But what we've also discovered
5:56is that a physiological signature of aging is that your sleep gets worse,
6:03especially that deep quality of sleep that I was just discussing.
6:08And only last year, we finally published evidence
6:11that these two things, they're not simply co-occurring,
6:14they are significantly interrelated.
6:18And it suggests that the disruption of deep sleep
6:22is an underappreciated factor
6:24that is contributing to cognitive decline or memory decline
6:28in aging, and most recently we've discovered,
6:32in Alzheimer's disease as well.
6:36Now, I know this is remarkably depressing news.
6:40It's in the mail. It's coming at you.
6:42But there's a potential silver lining here.
6:45Unlike many of the other factors that we know are associated with aging,
6:50for example changes in the physical structure of the brain,
6:54that's fiendishly difficult to treat.
6:57But that sleep is a missing piece in the explanatory puzzle
7:02of aging and Alzheimer's is exciting
7:04because we may be able to do something about it.
7:08And one way that we are approaching this at my sleep center
7:12is not by using sleeping pills, by the way.
7:15Unfortunately, they are blunt instruments that do not produce naturalistic sleep.
7:21Instead, we're actually developing a method based on this.
7:24It's called direct current brain stimulation.
7:28You insert a small amount of voltage into the brain,
7:31so small you typically don't feel it,
7:33but it has a measurable impact.
7:36Now if you apply this stimulation during sleep in young, healthy adults,
7:43as if you're sort of singing in time with those deep-sleep brainwaves,
7:47not only can you amplify the size of those deep-sleep brainwaves,
7:52but in doing so, we can almost double the amount of memory benefit
7:57that you get from sleep.
7:59The question now is whether we can translate
8:01this same affordable, potentially portable piece of technology
8:06into older adults and those with dementia.
8:10Can we restore back some healthy quality of deep sleep,
8:15and in doing so, can we salvage aspects of their learning
8:19and memory function?
8:21That is my real hope now.
8:24That's one of our moon-shot goals, as it were.
8:29So that's an example of sleep for your brain,
8:32but sleep is just as essential for your body.
8:37We've already spoken about sleep loss and your reproductive system.
8:41Or I could tell you about sleep loss and your cardiovascular system,
8:46and that all it takes is one hour.
8:49Because there is a global experiment performed on 1.6 billion people
8:55across 70 countries twice a year,
8:59and it's called daylight saving time.
9:02Now, in the spring, when we lose one hour of sleep,
9:06we see a subsequent 24-percent increase in heart attacks that following day.
9:14In the autumn, when we gain an hour of sleep,
9:18we see a 21-percent reduction in heart attacks.
9:23Isn't that incredible?
9:26And you see exactly the same profile for car crashes, road traffic accidents,
9:32even suicide rates.
9:36But as a deeper dive, I want to focus on this:
9:39sleep loss and your immune system.
9:43And here, I'll introduce these delightful blue elements in the image.
9:48They are called natural killer cells,
9:51and you can think of natural killer cells almost like the secret service agents
9:56of your immune system.
9:57They are very good at identifying dangerous, unwanted elements
10:02and eliminating them.
10:05In fact, what they're doing here is destroying a cancerous tumor mass.
10:10So what you wish for is a virile set of these immune assassins
10:16at all times,
10:18and tragically, that's what you don't have if you're not sleeping enough.
10:23So here in this experiment,
10:25you're not going to have your sleep deprived for an entire night,
10:29you're simply going to have your sleep restricted to four hours
10:32for one single night,
10:34and then we're going to look to see what's the percent reduction
10:37in immune cell activity that you suffer.
10:40And it's not small -- it's not 10 percent,
10:43it's not 20 percent.
10:45There was a 70-percent drop in natural killer cell activity.
10:51That's a concerning state of immune deficiency,
10:57and you can perhaps understand why we're now finding
11:00significant links between short sleep duration
11:04and your risk for the development of numerous forms of cancer.
11:09Currently, that list includes cancer of the bowel,
11:12cancer of the prostate and cancer of the breast.
11:17In fact, the link between a lack of sleep and cancer is now so strong
11:23that the World Health Organization
11:25has classified any form of nighttime shift work
11:29as a probable carcinogen,
11:33because of a disruption of your sleep-wake rhythms.
11:37So you may have heard of that old maxim
11:40that you can sleep when you're dead.
11:42Well, I'm being quite serious now --
11:44it is mortally unwise advice.
11:48We know this from epidemiological studies across millions of individuals.
11:53There's a simple truth:
11:55the shorter your sleep, the shorter your life.
11:58Short sleep predicts all-cause mortality.
12:04And if increasing your risk for the development of cancer
12:09or even Alzheimer's disease
12:11were not sufficiently disquieting,
12:15we have since discovered that a lack of sleep will even erode
12:19the very fabric of biological life itself,
12:24your DNA genetic code.
12:28So here in this study, they took a group of healthy adults
12:32and they limited them to six hours of sleep a night
12:35for one week,
12:37and then they measured the change in their gene activity profile
12:41relative to when those same individuals
12:43were getting a full eight hours of sleep a night.
12:47And there were two critical findings.
12:50First, a sizable and significant 711 genes
12:55were distorted in their activity,
12:57caused by a lack of sleep.
12:59The second result was that about half of those genes
13:03were actually increased in their activity.
13:05The other half were decreased.
13:08Now those genes that were switched off by a lack of sleep
13:11were genes associated with your immune system,
13:15so once again, you can see that immune deficiency.
13:19In contrast, those genes that were actually upregulated
13:22or increased by way of a lack of sleep,
13:24were genes associated with the promotion of tumors,
13:28genes associated with long-term chronic inflammation within the body,
13:33and genes associated with stress,
13:36and, as a consequence, cardiovascular disease.
13:41There is simply no aspect of your wellness
13:44that can retreat at the sign of sleep deprivation
13:48and get away unscathed.
13:50It's rather like a broken water pipe in your home.
13:53Sleep loss will leak down into every nook and cranny
13:57of your physiology,
14:00even tampering with the very DNA nucleic alphabet
14:03that spells out your daily health narrative.
14:09And at this point, you may be thinking,
14:12"Oh my goodness, how do I start to get better sleep?
14:15What are you tips for good sleep?"
14:18Well, beyond avoiding the damaging and harmful impact
14:22of alcohol and caffeine on sleep,
14:25and if you're struggling with sleep at night,
14:28avoiding naps during the day,
14:30I have two pieces of advice for you.
14:33The first is regularity.
14:35Go to bed at the same time, wake up at the same time,
14:39no matter whether it's the weekday or the weekend.
14:42Regularity is king,
14:45and it will anchor your sleep
14:47and improve the quantity and the quality of that sleep.
14:52The second is keep it cool.
14:56Your body needs to drop its core temperature
14:58by about two to three degrees Fahrenheit to initiate sleep
15:02and then to stay asleep,
15:04and it's the reason you will always find it easier
15:07to fall asleep in a room that's too cold
15:09than too hot.
15:12So aim for a bedroom temperature of around 65 degrees,
15:15or about 18 degrees Celsius.
15:17That's going to be optimal for the sleep of most people.
15:22And then finally, in taking a step back, then,
15:25what is the mission-critical statement here?
15:30Well, I think it may be this:
15:33sleep, unfortunately, is not an optional lifestyle luxury.
15:39Sleep is a nonnegotiable biological necessity.
15:44It is your life-support system,
15:48and it is Mother Nature's best effort yet at immortality.
15:54And the decimation of sleep throughout industrialized nations
15:59is having a catastrophic impact on our health, our wellness,
16:04even the safety and the education of our children.
16:08It's a silent sleep loss epidemic,
16:11and it's fast becoming one of the greatest public health challenges
16:14that we face in the 21st century.
16:20I believe it is now time for us to reclaim our right
16:25to a full night of sleep,
16:28and without embarrassment
16:30or that unfortunate stigma of laziness.
16:34And in doing so, we can be reunited with the most powerful elixir of life,
16:42the Swiss Army knife of health, as it were.
16:46And with that soapbox rant over,
16:49I will simply say, good night, good luck,
16:51and above all ...
16:54I do hope you sleep well.
16:56Thank you very much indeed.
16:58(Applause)
17:02Thank you.
17:03(Applause)
17:06Thank you so much.
17:08David Biello: No, no, no. Stay there for a second.
17:11Good job not running away, though. I appreciate that.
17:13So that was terrifying.
17:14Matt Walker: You're welcome. DB: Yes, thank you, thank you.
17:18Since we can't catch up on sleep, what are we supposed to do?
17:23What do we do when we're, like, tossing and turning in bed late at night
17:27or doing shift work or whatever else?
17:30MW: So you're right, we can't catch up on sleep.
17:32Sleep is not like the bank.
17:33You can't accumulate a debt
17:35and then hope to pay it off at a later point in time.
17:38I should also note the reason that it's so catastrophic
17:41and that our health deteriorates so quickly,
17:44first, it's because human beings are the only species
17:47that deliberately deprive themselves of sleep
17:50for no apparent reason.
17:52DB: Because we're smart.
17:53MW: And I make that point because it means that Mother Nature,
17:58throughout the course of evolution,
18:00has never had to face the challenge of this thing called sleep deprivation.
18:05So she's never developed a safety net,
18:08and that's why when you undersleep,
18:10things just sort of implode so quickly, both within the brain and the body.
18:15So you just have to prioritize.
18:18DB: OK, but tossing and turning in bed,
18:21what do I do?
18:22MW: So if you are staying in bed awake for too long,
18:27you should get out of bed and go to a different room
18:30and do something different.
18:32The reason is because your brain will very quickly associate your bedroom
18:36with the place of wakefulness,
18:38and you need to break that association.
18:41So only return to bed when you are sleepy,
18:44and that way you will relearn the association that you once had,
18:47which is your bed is the place of sleep.
18:50So the analogy would be,
18:52you'd never sit at the dinner table, waiting to get hungry,
18:55so why would you lie in bed, waiting to get sleepy?
18:59DB: Well, thank you for that wake-up call.
19:01Great job, Matt.
19:02MW: You're very welcome. Thank you very much.

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