One more reason to get a good night’s sleep | Jeff Iliff

翻译人员: Glimmer Wang 校对人员: Jing Peng

Sleep.

睡眠

It's something we spend about a third of our lives doing,

占用了我们一生三分之一的时间

but do any of us really understand what it's all about?

但是真正有人知道它到底是怎么回事吗？

Two thousand years ago, Galen,

两千年前

one of the most prominent medical researchers

古时候的名医

of the ancient world,

伽林提出

proposed that while we're awake,

当我们醒着的时候

our brain's motive force, its juice,

我们大脑的原动力，它的液体

would flow out to all the other parts of the body,

会流动到身体所有其他部位

animating them but leaving the brain all dried up,

维持它们的活力，但这却使大脑枯竭

and he thought that when we sleep,

并且他认为，在我们睡觉的时候

all this moisture that filled the rest of the body

这些充满了我们身体其他部位的液体

would come rushing back,

会再回到我们的大脑

rehydrating the brain

为大脑补充水分

and refreshing the mind.

并且使我们更有精神

Now, that sounds completely ridiculous to us now,

虽然这些观点如今我们听来很荒谬

but Galen was simply trying to explain

但是伽林很好的解释了那些

something about sleep

我们每天都要面对的

that we all deal with every day.

睡眠的事情

See, we all know based on our own experience

那么，根据自身的经验我们都知道

that when you sleep, it clears your mind,

如果我们睡觉了，我们的头脑会变的清醒

and when you don't sleep,

而如果我们没有睡觉

it leaves your mind murky.

大脑就会变糊涂

But while we know a great deal more about sleep now

我们现在对睡眠的了解

than when Galen was around,

比伽林那个时期多了很多

we still haven't understood why it is that sleep,

但是我们仍然不知道

of all of our activities, has this incredible

为什么在我们所有的活动中，只有睡眠

restorative function for the mind.

有如此这般可以促使我们 头脑变得清晰的功能

So today I want to tell you about

所以今天，我想给大家讲一些

some recent research

近期的研究

that may shed new light on this question.

这些研究可能会揭示这些问题。

We've found that sleep may actually be

我们发现，睡眠实际上可能是

a kind of elegant design solution

对大脑的一些最基本的要求

to some of the brain's most basic needs,

的一种简洁的解决方案，

a unique way that the brain

是大脑满足身体高需求的

meets the high demands and the narrow margins

一种独特的方式。

that set it apart from all the other organs of the body.

这种独特的方式 将它与我们身体其他器官区分开来。

So almost all the biology that we observe

所以几乎我们所研究的生物学

can be thought of as a series of problems

都可以被认为是生物体中 需要被解决的一些问题

and their corresponding solutions,

和相应的解决方案，

and the first problem that every organ must solve

并且，每个器官第一个要解决的问题

is a continuous supply of nutrients to fuel

就是提供持续不断的营养

all those cells of the body.

去供应身体的所有细胞。

In the brain, that is especially critical;

对大脑来说，这是至关重要的，

its intense electrical activity uses up

它巨大的电波活动

a quarter of the body's entire energy supply,

用尽了身体整个能量供应的四分之一

even though the brain accounts

即使大脑仅仅占据了

for only about two percent of the body's mass.

人体重量的百分之二。

So the circulatory system

所以这个循环系统

solves the nutrient delivery problem

通过血管的传输

by sending blood vessels to supply nutrients

将营养和氧气送到身体的每一个角落

and oxygen to every corner of our body.

来解决我们身体营养供应的问题

You can actually see it in this video here.

我们可以从视频中看到

Here, we're imaging blood vessels

这里，显示了活老鼠的

in the brain of a living mouse.

大脑中的血管

The blood vessels form a complex network

血管形成了一个复杂的网络

that fills the entire brain volume.

充满了整个大脑容量

They start at the surface of the brain,

它们从大脑的表层开始

and then they dive down into the tissue itself,

深入组织

and as they spread out, they supply nutrients

然后伸展开来，提供营养和氧气

and oxygen to each and every cell in the brain.

到大脑中的每一个细胞

Now, just as every cell requires

那么，就在每一个细胞

nutrients to fuel it,

消耗营养的同时

every cell also produces waste as a byproduct,

每个细胞也都会产生相应的垃圾和废物

and the clearance of that waste

那么，这些废物的清除

is the second basic problem

就成为了每个器官要解决的

that each organ has to solve.

第二个基本问题。

This diagram shows the body's lymphatic system,

这个图片展示了通过演变来 达到这种需求的系统——

which has evolved to meet this need.

淋巴系统

It's a second parallel network of vessels

它是贯穿整个身体的

that extends throughout the body.

第二套网络系统

It takes up proteins and other waste

淋巴管从细胞之间的间隙中

from the spaces between the cells,

得到蛋白质和其他垃圾

it collects them, and then dumps them into the blood

然后收集这些蛋白质和垃圾，将它们

so they can be disposed of.

卸到血液中去处理

But if you look really closely at this diagram,

但是如果你仔细地看这个图表

you'll see something

你会发现一些

that doesn't make a lot of sense.

不合常理的东西

So if we were to zoom into this guy's head,

假使我们钻进了这个人的脑袋

one of the things that you would see there

你会发现，

is that there are no lymphatic vessels in the brain.

大脑中没有淋巴管！

But that doesn't make a lot of sense, does it?

那不符合道理，不是吗？

I mean, the brain is this intensely active organ

我的意思是说，大脑是那么活跃的一个器官

that produces a correspondingly large amount of waste

它产生大量的废物，这些垃圾必须要被

that must be efficiently cleared.

及时、有效地清理掉

And yet, it lacks lymphatic vessels, which means that

然而大脑中却没有淋巴管，那就意味着

the approach that the rest of the body takes

身体的其他部位

to clearing away its waste

清除垃圾废物的途径

won't work in the brain.

在大脑中并不适用。

So how, then, does the brain solve

那么，大脑是怎样解决

its waste clearance problem?

它的垃圾清理问题的呢？

Well, that seemingly mundane question

那么，这个看上去普通的问题

is where our group first jumped into this story,

就是我们团队最初做这个项目的原因。

and what we found

我们发现，

as we dove down into the brain,

当我们深入到大脑中，

down among the neurons and the blood vessels,

一直深入到神经元和血管，

was that the brain's solution

去寻找大脑解决垃圾清理的问题

to the problem of waste clearance,

的机制时，得到的结果

it was really unexpected.

是出乎我们意料的

It was ingenious,

我们发现的东西很特别

but it was also beautiful.

又很美丽。

Let me tell you about what we found.

我来说说我们发现的东西

So the brain has this large pool

我们的大脑有一个区域，里面装满了

of clean, clear fluid called cerebrospinal fluid.

干净透明的液体，那种液体叫做脑脊液

We call it the CSF.

我们简称CSF（脑脊液）

The CSF fills the space that surrounds the brain,

CSF（脑脊液）填充了大脑周围的空间。

and wastes from inside the brain

来自大脑中的废物

make their way out to the CSF,

从大脑中出来，到达CSF（脑脊液）中

which gets dumped, along with the waste, into the blood.

CSF和废物一起卸下，进入血液。

So in that way, it sounds a lot like

照这样，听起来这就像一个

the lymphatic system, doesn't it?

淋巴系统，不是吗？

But what's interesting is that the fluid and the waste

但有趣的是，从大脑中出来的

from inside the brain,

液体和废物

they don't just percolate their way randomly

它们不是随意地渗透到

out to these pools of CSF.

CSF的区域中

Instead, there is a specialized network of plumbing

相反，有一个专门的管道网络，来组织和促进

that organizes and facilitates this process.

这个过程。

You can see that in these videos.

你可以从这些视频中看到。

Here, we're again imaging into the brain

看，我们又一次看到了

of living mice.

活老鼠的大脑

The frame on your left shows

在你左边的组织展示了

what's happening at the brain's surface,

大脑表层正在发生的事，

and the frame on your right shows

而你右边的组织显示了

what's happening down below the surface of the brain

大脑表层底下和它的组织

within the tissue itself.

所发生的事。

We've labeled the blood vessels in red,

我们把血管标记成红色

and the CSF that's surrounding the brain

把大脑周围的CSF标记成

will be in green.

绿色

Now, what was surprising to us

那么，让我们吃惊的是

was that the fluid on the outside of the brain,

大脑外面的液体（脑脊液）

it didn't stay on the outside.

它们不在外面呆着

Instead, the CSF was pumped back into

相反，CSF（脑脊液）沿着

and through the brain

血管外壁，流回

along the outsides of the blood vessels,

大脑中，并且

and as it flushed down into the brain

在它沿着这些血管

along the outsides of these vessels,

流向大脑的同时，

it was actually helping to clear away,

它正在忙于将废物

to clean the waste from the spaces

从这些

between the brain's cells.

脑细胞的间隙中带走。

If you think about it,

如果你仔细想想就会发现

using the outsides of these blood vessels like this

利用这些血管外壁

is a really clever design solution,

真的是一个巧妙设计的解决方法。

because the brain is enclosed

因为大脑在一个坚硬的头骨中

in a rigid skull

是封闭的，

and it's packed full of cells,

并且它里面装满了细胞。

so there is no extra space inside it

所以在大脑中已经没有空余的位置

for a whole second set of vessels like the lymphatic system.

留给第二套像淋巴系统那样的管路

Yet the blood vessels,

然而这些血管

they extend from the surface of the brain

却从大脑的表层延伸出来

down to reach every single cell in the brain,

到达大脑中的每一个独立的细胞，

which means that fluid

这也就意味着，脑脊液

that's traveling along the outsides of these vessels

只要沿着这些血管的外壁流动

can gain easy access to the entire brain's volume,

就可以轻易到达大脑中。

so it's actually this really clever way

所以这就是，安排一套血管

to repurpose one set of vessels, the blood vessels,

去代替第二套如淋巴管一样功能

to take over and replace the function

的一种巧妙办法。

of a second set of vessels, the lymphatic vessels,

这样就不需要

to make it so you don't need them.

那另外的一套淋巴管了。

And what's amazing is that no other organ

更神奇的是，没有其他任何一种器官

takes quite this approach

具有这种清理细胞之间废物

to clearing away the waste from between its cells.

的功能

This is a solution that is entirely unique to the brain.

这是大脑所独有的解决办法。

But our most surprising finding

但是，刚刚我所讲的这一切当中

was that all of this,

最最让我们感到

everything I just told you about,

惊奇的是

with all this fluid rushing through the brain,

大脑中所有这些液体的工作状态，

it's only happening in the sleeping brain.

只出现在睡眠时的大脑中！

Here, the video on the left

看，左边的这个视频

shows how much of the CSF is moving

显示了在一只醒着的老鼠的大脑中

through the brain of a living mouse while it's awake.

有多少脑脊液在流动——

It's almost nothing.

几乎没有。

Yet in the same animal,

然而同样是这只老鼠

if we wait just a little while until it's gone to sleep,

如果我们稍稍等待一下，到它睡着

what we see is that the CSF

我们就可以看到脑脊液

is rushing through the brain,

在大脑里快速地流动

and we discovered that at the same time

同时我们发现，

when the brain goes to sleep,

在大脑即将睡着的时候

the brain cells themselves seem to shrink,

脑细胞看起来变小了

opening up spaces in between them,

这样，细胞之间就产生了空隙

allowing fluid to rush through

这些空隙得以让脑脊液流动，

and allowing waste to be cleared out.

也让废物被清除了。

So it seems that Galen may actually have been

这样看起来，伽林提出的

sort of on the right track when he wrote about

人睡觉时大脑中会有液体流动

fluid rushing through the brain

的想法

when sleep came on.

应该是正确的思路。

Our own research, now it's 2,000 years later,

2000年后，我们自己的研究证明了

suggests that what's happening is that

大脑清醒时

when the brain is awake

所发生的一切。

and is at its most busy,

在大脑紧张工作时，

it puts off clearing away the waste

它一直将清理那些

from the spaces between its cells until later,

细胞空隙间的废物的工作推迟。

and then, when it goes to sleep

然后，在大脑要睡觉时

and doesn't have to be as busy,

它不必那样紧张工作，

it shifts into a kind of cleaning mode

大脑就切换到了“清理模式”，

to clear away the waste

开始清理

from the spaces between its cells,

脑细胞间隙之间

the waste that's accumulated throughout the day.

已经积累了一天的废物。

So it's actually a little bit like how you or I,

所以这有点像我，或者你，

we put off our household chores during the work week

我们在周内工作的时候，没有时间做家务

when we don't have time to get to it,

于是将家务推迟了

and then we play catch up on all the cleaning that we have to do

等周末到了，我们就会把所有要做的家务

when the weekend rolls around.

都做好。

Now, I've just talked a lot about waste clearance,

到现在，我们已经说了很多关于废物清理的事

but I haven't been very specific

但是我还没有具体介绍

about the kinds of waste

废物的种类——

that the brain needs to be clearing

那些为了保持我们健康，

during sleep in order to stay healthy.

大脑必须要清理的废物——的种类。

The waste product that these recent studies

近期的研究关注最多的废物

focused most on is amyloid-beta,

是淀粉样β蛋白

which is a protein that's made in the brain all the time.

这是一种大脑始终会产生的蛋白质

My brain's making amyloid-beta right now,

就在此刻，我的大脑就正在产生淀粉样β蛋白

and so is yours.

你的也是。

But in patients with Alzheimer's disease,

但是患有老年痴呆症的人

amyloid-beta builds up and aggregates

在他们脑细胞的间隙中

in the spaces between the brain's cells,

淀粉样β蛋白生成，聚集，

instead of being cleared away like it's supposed to be,

不能被及时清除。

and it's this buildup of amyloid-beta

淀粉样β蛋白的累积

that's thought to be one of the key steps

是形成这种疾病的

in the development of that terrible disease.

关键步骤。

So we measured how fast amyloid-beta is cleared

所以我们测量了大脑在清醒状态下

from the brain when it's awake

淀粉样β蛋白的清理速度

versus when it's asleep,

与大脑沉睡时的清理速度进行对比。

and we found that indeed,

我们发现

the clearance of amyloid-beta

在睡眠中的大脑

is much more rapid from the sleeping brain.

淀粉样β蛋白的清除速率更快。

So if sleep, then,

那么，如果睡眠

is part of the brain's solution

是大脑进行废物清理的

to the problem of waste clearance,

关键步骤，

then this may dramatically change how we think

那么这就会奇迹般地改变我们

about the relationship between sleep,

对睡眠，淀粉样β蛋白和老年痴呆症

amyloid-beta, and Alzheimer's disease.

的认识。

A series of recent clinical studies

一系列临床试验证明

suggest that among patients

在那些老年痴呆症

who haven't yet developed Alzheimer's disease,

还不是很严重的患者中，

worsening sleep quality and sleep duration

睡眠质量和时间的恶化

are associated with a greater amount

是与大脑中淀粉样β蛋白的的集聚

of amyloid-beta building up in the brain,

有着很大的关系的。

and while it's important to point out

然而，值得指出的是

that these studies don't prove

这些研究没有证实

that lack of sleep or poor sleep

睡眠的缺乏或者低质量的睡眠

cause Alzheimer's disease,

会引起老年痴呆症。

they do suggest that the failure of the brain

但明确指出如果大脑

to keep its house clean

不及时清理废物（如淀粉样β蛋白）

by clearing away waste like amyloid-beta

来维持它自身的清洁，

may contribute to the development

很可能会促进像老年痴呆症

of conditions like Alzheimer's.

这样的病症的发展。

So what this new research tells us, then,

那么，这个新的研究告诉我们，

is that the one thing that all of you

也就是我现在要告诉你们每个人的

already knew about sleep,

现在我们都知道，

that even Galen understood about sleep,

即使伽林也都知道，

that it refreshes and clears the mind,

关于睡眠最重要的一点

may actually be a big part

大概就是睡觉会使

of what sleep is all about.

我们的思维变得清醒。

See, you and I, we go to sleep

那么，我们，

every single night,

每晚都在睡觉，

but our brains, they never rest.

但是我们的大脑却从未休息过。

While our body is still

虽然我们的身体看起来不动了，

and our mind is off walking in dreams somewhere,

但是我们的思维却在到处梦游。

the elegant machinery of the brain

大脑的这些组织

is quietly hard at work

始终在辛苦地工作，

cleaning and maintaining

保持这个及其复杂的“机器”

this unimaginably complex machine.

的清洁。

Like our housework,

就好像我们的家务

it's a dirty and a thankless job,

那是个脏兮兮、费力不讨好的工作

but it's also important.

但是却是那么的重要。

In your house, if you stop cleaning your kitchen

如果你有一个月都不打扫

for a month,

你的厨房

your home will become completely unlivable

很快，你的家就会变得

very quickly.

不适合居住，

But in the brain, the consequences

但是如果换作大脑，拖延“不做家务”的结果

of falling behind may be much greater

将会比我们不清理厨房台面的结果

than the embarrassment of dirty countertops,

要严重得多。

because when it comes to cleaning the brain,

那是因为，对于大脑来说

it is the very health and function

不清理的后果会危及我们

of the mind and the body that's at stake,

思维、身体的健康与功能。

which is why understanding these

今天我们大脑所做的这些

very basic housekeeping functions of the brain today

基础的、“家务”一般的苦差事，

may be critical for preventing and treating

可能对防止与治疗明天的精神疾病

diseases of the mind tomorrow.

具有重要的意义。

Thank you.

谢谢。

(Applause)

（掌声）