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Why do we sleep?8,628,264 views | Russell Foster • TEDGlobal 2013
Circadian neuroscientistRussell Foster studies sleep and its role in our lives, examining how our perception of light influences our sleep-wake rhythms.
00:00
What I'd like to do today is talk about one of my favorite subjects, and that is the neuroscience of sleep.
00:08
Now, there is a sound --
00:11
(Alarm clock)
00:13
Ah, it worked! A sound that is desperately familiar to most of us, and of course it's the sound of the alarm clock. And what that truly ghastly, awful sound does is stop the single most important behavioral experience that we have, and that's sleep. If you're an average sort of person, 36 percent of your life will be spent asleep, which means that if you live to 90, then 32 years will have been spent entirely asleep.
00:49
Now what that 32 years is telling us is that sleep at some level is important. And yet, for most of us, we don't give sleep a second thought. We throw it away. We really just don't think about sleep. And so what I'd like to do today is change your views, change your ideas and your thoughts about sleep. And the journey that I want to take you on, we need to start by going back in time.
01:16
"Enjoy the honey-heavy dew of slumber." Any ideas who said that? Shakespeare's Julius Caesar. Yes, let me give you a few more quotes. "O sleep, O gentle sleep, nature's soft nurse, how have I frighted thee?" Shakespeare again, from -- I won't say it -- the Scottish play.
01:39
(Laughter)
01:42
From the same time: "Sleep is the golden chain that ties health and our bodies together." Extremely prophetic, by Thomas Dekker, another Elizabethan dramatist.
01:52
But if we jump forward 400 years, the tone about sleep changes somewhat. This is from Thomas Edison, from the beginning of the 20th century: "Sleep is a criminal waste of time and a heritage from our cave days." Bang!
02:07
(Laughter)
02:09
And if we also jump into the 1980s, some of you may remember that Margaret Thatcher was reported to have said, "Sleep is for wimps." And of course the infamous -- what was his name? -- the infamous Gordon Gekko from "Wall Street" said, "Money never sleeps."
02:26
What do we do in the 20th century about sleep? Well, of course, we use Thomas Edison's light bulb to invade the night, and we occupied the dark, and in the process of this occupation, we've treated sleep as an illness, almost. We've treated it as an enemy. At most now, I suppose, we tolerate the need for sleep, and at worst perhaps many of us think of sleep as an illness that needs some sort of a cure. And our ignorance about sleep is really quite profound. Why is it? Why do we abandon sleep in our thoughts? Well, it's because you don't do anything much while you're asleep, it seems. You don't eat. You don't drink. And you don't have sex. Well, most of us anyway. And so, therefore it's -- Sorry. It's a complete waste of time, right? Wrong. Actually, sleep is an incredibly important part of our biology, and neuroscientists are beginning to explain why it's so very important. So let's move to the brain.
03:31
Now, here we have a brain. This is donated by a social scientist, and they said they didn't know what it was or indeed, how to use it, so --
03:43
(Laughter)
03:46
Sorry. So I borrowed it. I don't think they noticed. OK.
03:52
(Laughter)
03:54
The point I'm trying to make is that when you're asleep, this thing doesn't shut down. In fact, some areas of the brain are actually more active during the sleep state than during the wake state. The other thing that's really important about sleep is that it doesn't arise from a single structure within the brain, but is to some extent a network property. If we flip the brain on its back -- I love this little bit of spinal cord here -- this bit here is the hypothalamus, and right under there is a whole raft of interesting structures, not least the biological clock. The biological clock tells us when it's good to be up, when it's good to be asleep, and what that structure does is interact with a whole raft of other areas within the hypothalamus, the lateral hypothalamus, the ventrolateral preoptic nuclei. All of those combine, and they send projections down to the brain stem here. The brain stem then projects forward and bathes the cortex, this wonderfully wrinkly bit over here, with neurotransmitters that keep us awake and essentially provide us with our consciousness. So sleep arises from a whole raft of different interactions within the brain, and essentially, sleep is turned on and off as a result of a range of interactions in here.
05:06
OK. So where have we got to? We've said that sleep is complicated and it takes 32 years of our life. But what I haven't explained is what sleep is about. So why do we sleep? And it won't surprise any of you that, of course, as scientists, we don't have a consensus. There are dozens of different ideas about why we sleep, and I'm going to outline three of those.
05:31
The first is sort of the restoration idea, and it's somewhat intuitive. Essentially, all the stuff we've burned up during the day, we restore, we replace, we rebuild during the night. And indeed, as an explanation, it goes back to Aristotle, so that's what -- 2,300 years ago. It's gone in and out of fashion. It's fashionable at the moment because what's been shown is that within the brain, a whole raft of genes have been shown to be turned on only during sleep, and those genes are associated with restoration and metabolic pathways. So there's good evidence for the whole restoration hypothesis.
06:06
What about energy conservation? Again, perhaps intuitive. You essentially sleep to save calories. Now, when you do the sums, though, it doesn't really pan out. If you compare an individual who has slept at night, or stayed awake and hasn't moved very much, the energy saving of sleeping is about 110 calories a night. Now, that's the equivalent of a hot dog bun. Now, I would say that a hot dog bun is kind of a meager return for such a complicated and demanding behavior as sleep. So I'm less convinced by the energy conservation idea.
06:46
But the third idea I'm quite attracted to, which is brain processing and memory consolidation. What we know is that, if after you've tried to learn a task, and you sleep-deprive individuals, the ability to learn that task is smashed. It's really hugely attenuated. So sleep and memory consolidation is also very important. However, it's not just the laying down of memory and recalling it. What's turned out to be really exciting is that our ability to come up with novel solutions to complex problems is hugely enhanced by a night of sleep. In fact, it's been estimated to give us a threefold advantage. Sleeping at night enhances our creativity. And what seems to be going on is that, in the brain, those neural connections that are important, those synaptic connections that are important, are linked and strengthened, while those that are less important tend to fade away and be less important.
07:40
OK. So we've had three explanations for why we might sleep, and I think the important thing to realize is that the details will vary, and it's probable we sleep for multiple different reasons. But sleep is not an indulgence. It's not some sort of thing that we can take on board rather casually. I think that sleep was once likened to an upgrade from economy to business class, you know, the equivalent of. It's not even an upgrade from economy to first class. The critical thing to realize is that if you don't sleep, you don't fly. Essentially, you never get there. And what's extraordinary about much of our society these days is that we are desperately sleep-deprived.
08:24
So let's now look at sleep deprivation. Huge sectors of society are sleep-deprived, and let's look at our sleep-o-meter. So in the 1950s, good data suggests that most of us were getting around eight hours of sleep a night. Nowadays, we sleep one and a half to two hours less every night, so we're in the six-and-a-half-hours every-night league. For teenagers, it's worse, much worse. They need nine hours for full brain performance, and many of them, on a school night, are only getting five hours of sleep. It's simply not enough. If we think about other sectors of society -- the aged; if you are aged, then your ability to sleep in a single block is somewhat disrupted, and many sleep, again, less than five hours a night.
09:10
Shift work. Shift work is extraordinary, perhaps 20 percent of the working population, and the body clock does not shift to the demands of working at night. It's locked onto the same light-dark cycle as the rest of us. So when the poor old shift worker is going home to try and sleep during the day, desperately tired, the body clock is saying, "Wake up. This is the time to be awake." So the quality of sleep that you get as a night shift worker is usually very poor, again in that sort of five-hour region. And then, of course, tens of millions of people suffer from jet lag. So who here has jet lag? Well, my goodness gracious. Well, thank you very much indeed for not falling asleep, because that's what your brain is craving.
09:51
One of the things that the brain does is indulge in micro-sleeps, this involuntary falling asleep, and you have essentially no control over it. Now, micro-sleeps can be sort of somewhat embarrassing, but they can also be deadly. It's been estimated that 31 percent of drivers will fall asleep at the wheel at least once in their life, and in the US, the statistics are pretty good: 100,000 accidents on the freeway have been associated with tiredness, loss of vigilance, and falling asleep -- a hundred thousand a year. It's extraordinary. At another level of terror, we dip into the tragic accidents at Chernobyl and indeed the space shuttle Challenger, which was so tragically lost. And in the investigations that followed those disasters, poor judgment as a result of extended shift work and loss of vigilance and tiredness was attributed to a big chunk of those disasters. When you're tired and you lack sleep, you have poor memory, you have poor creativity, you have increased impulsiveness, and you have overall poor judgment. But my friends, it's so much worse than that.
11:04
(Laughter)
11:06
If you are a tired brain, the brain is craving things to wake it up. So drugs, stimulants. Caffeine represents the stimulant of choice across much of the Western world. Much of the day is fueled by caffeine, and if you're a really naughty tired brain, nicotine. Of course, you're fueling the waking state with these stimulants, and then, of course, it gets to 11 o'clock at night, and the brain says to itself, "Actually, I need to be asleep fairly shortly. What do we do about that when I'm feeling completely wired?" Well, of course, you then resort to alcohol. Now alcohol, short-term, you know, once or twice, to use to mildly sedate you, can be very useful. It can actually ease the sleep transition. But what you must be so aware of is that alcohol doesn't provide sleep. A biological mimic for sleep, it sedates you. So it actually harms some of the neural processing that's going on during memory consolidation and memory recall. So it's a short-term acute measure, but for goodness sake, don't become addicted to alcohol as a way of getting to sleep every night.
12:10
Another connection between loss of sleep is weight gain. If you sleep around about five hours or less every night, then you have a 50 percent likelihood of being obese. What's the connection here? Well, sleep loss seems to give rise to the release of the hormone ghrelin, the hunger hormone. Ghrelin is released. It gets to the brain. The brain says, "I need carbohydrates," and what it does is seek out carbohydrates and particularly sugars. So there's a link between tiredness and the metabolic predisposition for weight gain: stress. Tired people are massively stressed. And one of the things of stress, of course, is loss of memory, which is what I sort of just then had a little lapse of. But stress is so much more. So, if you're acutely stressed, not a great problem, but it's sustained stress associated with sleep loss that's the problem. Sustained stress leads to suppressed immunity. And so, tired people tend to have higher rates of overall infection, and there's some very good studies showing that shift workers, for example, have higher rates of cancer. Increased levels of stress throw glucose into the circulation. Glucose becomes a dominant part of the vasculature and essentially you become glucose intolerant. Therefore, diabetes 2. Stress increases cardiovascular disease as a result of raising blood pressure. So there's a whole raft of things associated with sleep loss that are more than just a mildly impaired brain, which is where I think most people think that sleep loss resides.
13:45
So at this point in the talk, this is a nice time to think, "Well, do you think on the whole I'm getting enough sleep?" So a quick show of hands. Who feels that they're getting enough sleep here? Oh. Well, that's pretty impressive. Good. We'll talk more about that later, about what are your tips.
14:02
So most of us, of course, ask the question, "How do I know whether I'm getting enough sleep?" Well, it's not rocket science. If you need an alarm clock to get you out of bed in the morning, if you are taking a long time to get up, if you need lots of stimulants, if you're grumpy, if you're irritable, if you're told by your work colleagues that you're looking tired and irritable, chances are you are sleep-deprived. Listen to them. Listen to yourself.
14:25
What do you do? Well -- and this is slightly offensive -- sleep for dummies.
14:30
(Laughter)
14:32
Make your bedroom a haven for sleep. The first critical thing is make it as dark as you possibly can, and also make it slightly cool. Very important. Actually, reduce your amount of light exposure at least half an hour before you go to bed. Light increases levels of alertness and will delay sleep. What's the last thing that most of us do before we go to bed? We stand in a massively lit bathroom, looking into the mirror cleaning our teeth. It's the worst thing we can possibly do before we go to sleep. Turn off those mobile phones. Turn off those computers. Turn off all of those things that are also going to excite the brain. Try not to drink caffeine too late in the day, ideally not after lunch.
15:13
Now, we've set about reducing light exposure before you go to bed, but light exposure in the morning is very good at setting the biological clock to the light-dark cycle. So seek out morning light. Basically, listen to yourself. Wind down. Do those sorts of things that you know are going to ease you off into the honey-heavy dew of slumber.
15:34
OK. That's some facts. What about some myths?
15:37
Teenagers are lazy. No. Poor things. They have a biological predisposition to go to bed late and get up late, so give them a break.
15:45
We need eight hours of sleep a night. That's an average. Some people need more. Some people need less. And what you need to do is listen to your body. Do you need that much or do you need more? Simple as that.
15:58
Old people need less sleep. Not true. The sleep demands of the aged do not go down. Essentially, sleep fragments and becomes less robust, but sleep requirements do not go down.
16:11
And the fourth myth is early to bed, early to rise makes a man healthy, wealthy and wise. Well, that's wrong at so many different levels.
16:21
(Laughter)
16:23
There is no evidence that getting up early and going to bed early gives you more wealth at all. There's no difference in socioeconomic status. In my experience, the only difference between morning people and evening people is that those people that get up in the morning early are just horribly smug.
16:39
(Laughter)
16:41
(Applause)
16:44
OK. So for the last few minutes, what I want to do is change gears and talk about some really new, breaking areas of neuroscience, which is the association between mental health, mental illness and sleep disruption. We've known for 130 years that in severe mental illness, there is always, always sleep disruption, but it's been largely ignored. In the 1970s, when people started to think about this again, they said, "Yes, well, of course you have sleep disruption in schizophrenia, because they're on antipsychotics. It's the antipsychotics causing the sleep problems," ignoring the fact that for a hundred years previously, sleep disruption had been reported before antipsychotics.
17:25
So what's going on? Several groups are studying conditions like depression, schizophrenia and bipolar and what's going on in terms of sleep disruption. We have a big study which we published last year on schizophrenia, and the data were quite extraordinary. In those individuals with schizophrenia, much of the time, they were awake during the night phase and then they were asleep during the day. Other groups showed no 24-hour patterns whatsoever -- their sleep was absolutely smashed. And some had no ability to regulate their sleep by the light-dark cycle. They were getting up later and later and later and later each night. It was smashed.
18:06
So what's going on? And the really exciting news is that mental illness and sleep are not simply associated, but they are physically linked within the brain. The neural networks that predispose you to normal sleep, give you normal sleep, and those that give you normal mental health, are overlapping. And what's the evidence for that? Well, genes that have been shown to be very important in the generation of normal sleep, when mutated, when changed, also predispose individuals to mental health problems. And last year, we published a study which showed that a gene that's been linked to schizophrenia, when mutated, also smashes the sleep. So we have evidence of a genuine mechanistic overlap between these two important systems.
18:53
Other work flowed from these studies. The first was that sleep disruption actually precedes certain types of mental illness, and we've shown that in those young individuals who are at high risk of developing bipolar disorder, they already have a sleep abnormality prior to any clinical diagnosis of bipolar. The other bit of data was that sleep disruption may actually exacerbate, make worse, the mental illness state. My colleague Dan Freeman has used a range of agents which have stabilized sleep and reduced levels of paranoia in those individuals by 50 percent.
19:34
So what have we got? We've got, in these connections, some really exciting things. In terms of the neuroscience, by understanding these two systems, we're really beginning to understand how both sleep and mental illness are generated and regulated within the brain. The second area is that if we can use sleep and sleep disruption as an early warning signal, then we have the chance of going in. If we know these individuals are vulnerable, early intervention then becomes possible. And the third, which I think is the most exciting, is that we can think of the sleep centers within the brain as a new therapeutic target. Stabilize sleep in those individuals who are vulnerable, we can certainly make them healthier, but also alleviate some of the appalling symptoms of mental illness.
20:21
So let me just finish. What I started by saying is: Take sleep seriously. Our attitudes toward sleep are so very different from a pre-industrial age, when we were almost wrapped in a duvet. We used to understand intuitively the importance of sleep. And this isn't some sort of crystal-waving nonsense. This is a pragmatic response to good health. If you have good sleep, it increases your concentration, attention, decision-making, creativity, social skills, health. If you get sleep, it reduces your mood changes, your stress, your levels of anger, your impulsivity, and your tendency to drink and take drugs. And we finished by saying that an understanding of the neuroscience of sleep is really informing the way we think about some of the causes of mental illness, and indeed is providing us new ways to treat these incredibly debilitating conditions.
21:15
Jim Butcher, the fantasy writer, said, "Sleep is God. Go worship." And I can only recommend that you do the same.
21:23
Thank you for your attention.
21:25
(Applause)
Ning Zhang, Translator
xuan wang, Reviewer
00:00
我今天想和大家探讨的是 一个我很喜欢的主题， 神经科学睡眠。
00:08
现在，有一个声音—— （闹钟声）—— 哈哈，它响了—— 我们大部人对这声音都非常非常熟悉， 当然，这是闹钟声。 这个讨人厌的可怕的声音做了什么呢 它终止了我们所拥有的非常重要的一种行为体验 那就是睡眠。 如果你是一个正常人， 那么你生命的36%都将花在睡眠上， 这意味着如果你活到90岁， 那么32年的时间完完全全地都用在了睡眠上。
00:49
这32年告诉我们 在某种程度上睡眠是重要的。 但是，对于大部人来说，我们不会对睡眠这件事多加思索。 我们把它扔掉了。 关于睡眠，我们没有真正好好思考过。 所以，今天我要做的就是 改变你们对睡眠的认识， 改变你们对睡眠的想法和观点。 在带领你们开始这段旅程的时候， 我们先来个时光倒流。
01:16
“享受沉稳香甜的睡眠甘露。” 知道谁说过这话吗？ 莎士比亚的凯撒大帝。 对，我再给你们多念点引用的句子吧。 “噢，睡眠，噢，温柔的睡眠，自然界的温柔护士， 我吓坏你了吗？” 又是莎士比亚的，但我不会说出处。 那是一个苏格兰戏剧。［更正：应为亨利四世，第二部分］ （笑声） 来自同一时代： “睡眠是一个金链条 将我们的健康和身体紧联。” 托马斯·德克尔曾说过的，非常有预见性。 另一位伊丽莎白时代的剧作家。
01:52
如果我们前进400年， 关于睡眠的论调变了， 下面这一句是托马斯·爱迪生说的，在20世纪初期， “睡眠是犯罪性的时间浪费， 是原始人的遗物。” 砰。 （笑声） 如果我们再跳到1980年代， 你们有些人可能会记得撒切尔夫人 在一次采访中曾经说道“懦夫才需要睡觉。” 当然，还有名声不怎么样的人——他叫什么来着？ 对，就是声名狼藉的《华尔街》电影中的戈登·盖柯， 他说”金钱从不睡觉。“
02:26
在20世纪，我们对睡眠做了什么？ 当然，我们用托马斯·爱迪生的灯泡 侵袭了夜晚，而且我们也占领了黑暗， 并且在这个占领的过程中， 我们对待睡眠几乎象对待一种疾病。 我们把它当成敌人。 现在，最多，我想我们容忍着对睡眠的需要， 但在最坏的情况下，也许很多人认为睡眠 是一种疾病，某种程度上它需要被治愈。 我们对睡眠的无知真的是很严重。
02:58
为什么？为什么我们不想睡觉呢？ 因为，在你睡觉时， 看起来，你不做任何事情。 你不吃。你不喝。 你也没有发生性行为。 我指的是大部分人没有。 所以它是—— 抱歉。睡眠完全是浪费时间，对不对？ 错了！事实上，睡眠对我们至关重要。 神经科学家已经开始解释为什么 睡眠是那么重要。 我们来看看大脑。
03:31
这里有一个大脑。 这是一个社会学家捐赠的， 他们说他们不知道这是什么， 或者他们不知道该怎么用它，所以—— （笑声） 抱歉。 所以，被我借过来了。我觉得他们没注意到。好吧。 （笑声）
03:54
我想说的是当你在睡觉时， 大脑是不会停止的。 事实是，当人在睡眠时，大脑的某些区域 要比醒着的时候更活跃。 另外一个关于睡眠的非常重要的事是 它不会从大脑内部的单一的结构产生， 而是在某种程度上由一个网状的结构产生， 如果我们看大脑的后面—— 我喜欢这个，这是脊髓 这个点是下丘脑 在这下面是一个有趣的结构， 尤其是生物钟。 生物钟告诉我们何时该起床， 何时该睡觉， 这个结构是与下脑丘内的 其它部位互动， 与下丘脑外侧，脑侧室前视核互动。 所有这些组合在一起，他们发出预测信息 向下传送到这里的脑干。 之后，脑干再将信息发送出 并且包裹住大脑皮层，覆盖这里的这些漂亮的褶皱型的物质， 和神经递质一起让我们保持清醒 让我们有意识。 所以睡眠是从脑内 不同部位的相互作用而产生的， 根本上说，睡眠是在这里一系列互动活动的作用下 产生和停止。
05:05
好。我们讲到哪里了？ 我们已经说过睡眠是复杂的 和它占据了我们生命的32 年时间。 但我还没解释什么是睡眠。 那么我们为什么睡觉？ 它不会给你们任何一个人惊喜，当然， 科学家们还没达成一致的观点。 关于为什么我们睡觉，有几十个不同的说法， 我从中提炼出三点原因。
05:31
第一，是修复的观点 这个观点有点直观假设。 基本上，在白天我们已经燃烧用尽了所有精力， 我们需要在夜间得到修复，更换，和重新生成。 的确，作为一种解释， 这要追溯到亚里斯多德 所以也就是要追溯到2300年前。 这个观点曾经流行过。 当时流行的原因是 人们发现只有在睡眠时, 大脑内部的很多基因才会活动起来， 而且这些基因与修复 和新陈代谢的途径相关联。 所以这就为这整个修复的假设观点提供了证据。
06:06
关于节约能源的观点呢？ 这或许也是一种直观的假设。 基本上，当你睡觉时你是在保存热量。 现在，当你算个总数的话， 这个观点并没说服力。 如果你把一个晚上睡觉的与另一个熬夜的但没有做多少运动的人 放一起比较， 那么睡一晚上大约存了110 卡路里热量。 这是相当于一个热狗面包。 我要说，对于睡眠，这样一个复杂和必须的行为来说， 最后才换来一个热狗面包， 实在是有点说不过去。 所以我不太相信这种能量保存的观点。
06:46
但第三个观点很吸引我， 就是大脑处理和记忆整合。 我们知道的是，如果你试图学习某项事物， 如果你的睡眠被剥夺了的话， 那么学习这项事物的能力就被破坏了。 这真是巨大的退步。 所以睡眠和记忆的巩固也是非常重要的。 然而，我们不只是躺下来 开始回顾。 真正让人兴奋的是 我们用新颖的办法解决复杂问题的能力 被一晚上的睡眠给大大加强了。 事实上，这带给我们三倍的优势。 晚上睡觉增强了我们的创造力。 在大脑中， 那些重要的神经连接将继续工作， 那些重要的突触连接 会连接在一起并得到加强， 而那些不重要的东西 会被弱化，显得不重要了。
07:40
好，这样我们有三种解释，为什么我们要睡觉， 我认为我们需要意识到 细节是多样的，我们可能是有很多不同的原因要睡觉。 但是，睡眠不是一种放纵。 它不是某种我们可以随随便便看待的事情。 我认为睡眠可以比喻为 从经济舱升级到商务舱。 但它没到从经济舱升级到头等舱那个地步。 最关键的事是， 如果你不睡觉，就好比你无法起飞。 从根本上讲，你也无法做成任何事情， 如今，我们的社会 却拼命绝望地剥夺我们的睡眠。
08:24
所以，我们现在看看睡眠的剥夺。 社会中大部分人的睡眠都被剥夺了， 让我们看看我们的睡眠计量表。 在 50 年代，良好的数据表明我们大多数人 每晚约睡8 个小时。 如今，我们每晚少睡一个半到两个小时， 所以，我们每晚只睡6个半小时。 对于青少年来说、 情况更加糟糕。 为了大脑的充足表现，他们需要睡够9 个小时， 但他们很多人，在上学的夜晚， 只睡5个小时。 这是根本不够的。 想想社会的其他人群，老年人， 老年人的睡眠 被打断成好几部分， 加起来一晚上睡眠少于五个小时。 轮班工作的人 大概占工作人口的20%， 但人体生物钟 不会随夜间工作的要求而调整。 它和我们其他人一样拥有相同的光暗周期。 所以当可怜的轮班工人非常疲惫地回到家 试着在白天睡觉， 人体生物钟会说，"醒醒。现在应该是醒着的时间"。 所以身为一名值夜班工作者的睡眠质量 通常非常差，他们同样被划分为只睡5小时的人群里。 然后，数以千万的人们 受时差影响。 那么，在座的有谁受时差影响？ 我的天啊。 好，非常感谢您现在没睡着， 因为那是你大脑正在渴望的。
09:51
大脑还会做一件事 它会沉溺于微睡眠， 这是非自愿性的睡眠， 你根本无法控制它。 微睡眠让人尴尬， 但他们也可以致命。 据估计，31%的司机 一生中至少有一次在开车时睡着了， 在美国，统计数字显示惊人： 在高速公路上发生的10万起交通事故 与疲倦，放松警惕， 和打瞌睡有关。 平均每年10 万起。这很惊人。 另一种恐怖是 我们看到切尔诺贝利的事故 和挑战者航天飞机失事， 都是损失惨重。 随后的调查中发现 由于轮班工作者延长的工作时间所造成的 判断力差，丧失警惕和疲倦 是导致悲剧的主因。
10:48
所以，当你累了，缺觉了， 你的记忆力变差，你的创造力降低， 你容易冲动， 你的整体判断也会下降。 但我的朋友们，还有比这更糟的事呢。
11:03
（笑声）
11:06
如果大脑累了， 它渴望某种东西来唤醒它。 所以，药品，兴奋剂，和咖啡因是大多数 西方世界的选择。 大部分时间我们用咖啡因提神， 如果大脑过度劳累，就会选择尼古丁。 当然，你要保持清醒状态， 就会用这些兴奋剂， 然后，到了晚上11点时， 大脑会说，"啊，实际上， 我需要小睡一会。 当我们特困的时候，我们该做点什么呢?" 嗯，当然，你会求助于酒精。 酒精，短期内用一两次， 可以让你轻度镇静，这非常有用。 它实际上可以帮助睡眠的过渡。 但你必须意识到 酒精只会麻醉你，但它不能提供真正的睡眠， 那只是一个生物模仿性的睡眠。 它实际上会危害神经活动过程， 这包含记忆的强化 和回忆。 所以它是一个短期急性措施， 但看在上帝的份上，千万不要上瘾， 不要每晚都得依靠酒精睡眠。
12:09
另外，睡眠和体重增加有关联。 如果你每晚只睡5个小时或更少， 那么你有 50%超重的可能性。 这两者之间的关联是什么？ 睡眠缺失看起来会释放 更多的荷尔蒙生长激素（ghrelin），即饥饿激素。 饥饿激素（ghrelin）一旦被释放， 它就到达大脑，大脑就会说"我需要碳水化合物，" 它会寻找碳水化合物 特别是糖。 这就是疲倦和增重的代谢倾向 两者之间的关联。
12:42
压力。疲惫的人压力都很大。 压力造成的后果之一 是记忆丧失， 这就是为什么刚刚我跳过一小段。 但压力影响更大。 所以如果只是突然感受到压力，这不是一个很大的问题， 但如果是一个与睡眠损失相关的 持续的压力，这会是个问题。 所以，持续的压力导致免疫功能被抑制， 所以，疲惫的人更容易受到感染， 有一些很好的研究显示 轮班工作者，有较高的癌症患病率。 压力会增加血液循环中的葡萄糖。 当葡萄糖成为血管中重要成分时， 身体对葡萄糖的耐受性降低。 因此，会患上2型糖尿病。 压力会增加心血管疾病 会升高血压。 所以，有很多与睡眠损失相关的事情 并不仅仅像大多数人认为的 睡眠不足只会引起 大脑轻度受损。
13:45
现在，这个演讲是个很好的机会让我们想想， 你觉得整体上而言，你的睡眠充足吗？ 请举手让我们看看。 这里谁觉得自己睡眠充足？ 噢，非常好。 很好。我们稍后会详细谈谈你们入睡的秘诀是什么。
14:02
大部分人都会问个问题， "怎么知道我是否得到足够的睡眠?" 嗯，这不是深奥的科学。 如果早上起床你需要一个闹钟， 如果你花很长时间起床， 如果你需要大量的兴奋剂， 如果你脾气乖戾易怒， 如果你的同事告诉你 您看起来疲倦和易怒、 你很可能就是睡眠不足。 听听他们，听听你自己。
14:25
你该怎么办呢？ 这有点冒犯之意。 白痴睡眠法： 将你的卧室变成睡眠天堂。 关键的第一步是让卧室尽可能的保持黑暗， 并让室温稍微低一些。这非常重要。 实际上，至少在睡前半个小时 就需要少接受光线的照射。 光线增加警醒度，并延迟睡眠。 我们大多数人睡前做的最后一件事是什么？ 我们站在一个光线明亮的浴室 对着镜子清洁牙齿。 这是入睡前 最不适合做的事。 请关闭移动电话，计算机。 关闭所有的那些会让大脑兴奋的东西。 尽量不要在一天太晚的时间喝咖啡因 最好午餐后就不要喝了。 现在，我们降低睡前接受的光线， 但早上接受的光线 对调整生物钟的光暗周期非常有益。 所以早上要迎接晨光。 根本地说，你要听听你自己。 放轻松。做那些可以舒缓， 让你平静的 进入一个沉稳香甜的睡眠甘露的事情。
15:34
好，这是一些事实。其他的误区是什么？
15:37
青少年很懒惰，错了！可怜的孩子们。 他们的生理 倾向于晚睡晚起，所以饶了他们吧。
15:45
我们每晚需要8个小时的睡眠。 这是一个平均值。有些人需要更多，有些人需要较少。 你需要做的就是听从你的身体。 睡那么多就够了或者你还需要更多吗？ 就这么简单。
15:58
老年人需要较少的睡眠。不正确。 老年人的睡眠不会随年纪增长而减少。 从根本上讲，是睡眠变成片段式的，变得没那么沉稳了， 但睡眠的需求不会减弱。
16:11
第四个误区是， 早睡早起 使人拥有健康、 财富和智慧。 在很多层面上，这个观点都是错的。 （笑声） 没有证据表明 早睡早起给你更多的财富。 在社会经济地位上没有区别。 以我的经验， 早起和晚起的人的唯一区别在于 只是那些清晨早起的人 会沾沾自喜罢了。
16:40（笑声）（掌声）
16:44
所以，最后几分钟， 我想换个话题 和大家谈谈新的突破性的神经科学领域的发现， 这些与心理健康，精神疾病 和睡眠失调有关。 130年来，我们都知道， 重症精神疾病和失调有关 但这一认识却被大家忽视了。 在20 世纪70年代，当人们重新开始想起这件事， 他们说，"是的，精神分裂症患者当然会受到睡眠干扰 因为他们服用抗精神病药物。 是这些药物导致了睡眠问题，" 这忽视了之前一百年来的事实， 事实显示睡眠失调发生于用药之前。
17:25
所以到底怎么回事？ 有很多团队和小组正在研究 抑郁症、 精神分裂症和双重人格， 和睡眠失调的原因。 去年我们针对精神分裂症患者发表了一项重大的研究， 那些数据非同寻常。 那些患有精神分裂症的人， 很多的时间，他们在晚上睡眠的时间却是醒着的 然后他们白天睡着了。 其他团队显示他们没有遵守24小时的生理周期。 他们的睡眠完全被摧毁了。 有些人无法通过光暗周期来调节睡眠的能力。 他们起的越来越晚睡的也越来越晚 睡眠被摧毁了。
18:06
为什么会这样呢？ 让人兴奋的消息是， 精神疾病和睡眠并不是简单的关联 而是在脑部有生理上的连接。 神经网络的正常连接让你倾向于正常睡眠 正常的睡眠 与帮助你获得正常心理健康的物质重叠。 证据是什么？ 能令睡眠正常的 那些非常重要的基因 当它们变异和发生改变时， 人的心理健康也会倾向产生问题。 过去一年，我们发表了一份研究报告 表明与精神分裂症相连的基因， 当它们变异时也会摧毁睡眠。 所以我们有证据显示两大系统有某种 重要的巧妙的关联。
18:53
还有其他相关的研究。 第一是，睡眠失调会发生在 某些特定类型的精神病之前， 我们已经证明， 那些极容易患双重人格的年轻人， 他们在诊断出双重人格之前 已经有睡眠失常的表现。 其他关于睡眠失调的数据 实际上可能 会加剧精神疾病。 我的同事丹 · 弗里曼已使用一系列方法 可以稳定偏执狂患者的睡眠 减轻这些人50%的症状。
19:34
所以我们得到了什么？ 我们看到了这些令人兴奋的关联。 在神经科学领域， 通过了解这两大系统， 我们真正开始理解 睡眠和精神疾病是由脑部产生和调控的。 第二是，如果我们可以使用睡眠 并把睡眠失调作为一个早期的预警信号， 那么我们就有机会介入。 如果我们知道这些人是脆弱的 早期的干预会成为可能。 第三，也是我认为最令人兴奋的 是我们可以把脑部的睡眠中心 作为一个新的治疗目标。 稳定那些脆弱人群的睡眠 我们当然可以让他们更健康， 也会缓解精神疾病带来的不适。
20:21
我来做个总结。 我们需要认真对待睡眠。 从工业化时代前， 我们对睡眠的态度是非常不同的， 那时，我们热爱和留恋睡眠， 我们过去是理解睡眠的重要性的。 这不是什么无稽之谈。 这是对于良好的健康的正常的反应。 如果你有良好的睡眠，它能增加你的集中力， 注意力、 决策力、 创造力、 社会技能、和 健康。 如果你入睡了，它能减少你的情绪变化，你的压力， 你的愤怒，你的冲动， 也减少你喝酒和服用药物的倾向。 我们可以这样总结 对睡眠的神经科学的理解 正在改变 我们对精神疾病成因的看法， 也的确为这些极端状况的病情 提供了新的治疗方式。
21:15
幻想作家，吉姆·布契曾说， "睡眠是上帝。去崇拜它吧"。 我会建议你们也这样做。
21:23
谢谢大家的关注。
21:24 （掌声）
https://www.ted.com/talks/russell_foster_why_do_we_sleep/transcript?referrer=playlist-talks_to_inspire_you_to_go_to&autoplay=true
