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In case you didn't know, 2015 is the International Year of Light.
也许有的观众不知道，2015年是国际光之年。
So, I thought I'd tell you just a little bit about the impact of light on our health.
我想跟大家讲一点光线对人的身体的影响的知识。
My lab uses fruit flies to study sleep and wake patterns,
我的实验室用果蝇来研究睡眠和清醒的模式，
but what I want to talk today is primarily light and its impact on health.
但我今天想讲的主要是光线以及它对健康的影响。
So, of course, we live on this planet that spins around its axis as it's orbiting the Sun.
当然，我们生存的这个星球会绕着太阳自转。
As a consequence of that, one of the basic facts of life on Earth is that you're exposed to light-dark cycles every single day.
因此，关于地球生命的一个基本常识就是每天他们都会经历日夜的变化。
Here you see the side of the Earth that's facing the Sun, is light, and the other one is dark,
大家可以看到地球面对着太阳的这一面是亮的，另一面是暗的，
and actually, I think we have so much light here that the dark side is kind of washed-out.
我认为这边的亮度太强了以至于有暗处的一部分已经看不见了。
But if the light was a little bit lower, you could see that there are lights all over the places on Earth,
但如果光线再暗一点，你们就可以看见地球上各个地方都是有光的，
at least where there's solid ground, just not above water.
至少那些水上的陆地都是有光的。
And that's maybe a little bit more clear from this picture which is a composite Google image of Earth from above,
这张图可能更清楚一点，这张谷歌合成图是从地球上空拍到的，
at night, and I think that this is a really stunning image.
是地球的夜晚，我觉得这张图很美。
It's stunningly beautiful, but it's also stunning to think about the amount of light that we're enveloping the Earth on,
美的惊人，但我们在地球上点亮了这么多灯这一事实同样惊人，
and, at the time of day when, for pretty much all of our evolutionary history, the Earth has been dark.
在人类进化的整个历史上，地球在部分时间是黑暗的。
There's this funny story that I don't know if it's true, but I like it,
有一个有趣的故事，我不知真假，但是很喜欢，
I think it's a good story, where in 1994, in LA,
这是个挺好的故事，1994年，洛杉矶，
police started getting reports of people seeing a strange white cloud in the sky, and they didn't know what this was.
警察不断收到报告说人们看见天上有一朵奇怪的白云，而他们不知道那是什么。
They wondered if they should be worried.
大家想知道是否需要为此担心。
It turned out LA had just suffered a major earthquake which resulted in citywide blackouts.
结果原因是洛杉矶刚经历了一场地震，城市部分地区停电了。
So, many people for the first time in many years,
那是很多人很多年来第一次，
or perhaps the first time in their lives, had an unobstructed view of the night sky.
或者说这一生中第一次在没有遮挡的情况下看见夜空。
In fact, what they were seeing was not a trail from some alien spaceship,
实际上他们所看见的并不是什么外星人飞船的轨迹，
but it was a glimpse of our own home galaxy, the Milky Way.
只是我们的家乡，银河系的样子。
This may sound quite incredible to you until I show you this next picture.
可能你们觉得难以置信，那么请看看这张照片。
Here's a picture that this guy, Todd Carlson, from Canada, took of his house,
这张照片的内容是加拿大人托德·卡尔森拍摄的自己的房子，
a fairly typical-looking house, a typical-looking sky, at least for those of us living in Boston, or surrounding areas.
房子外形很常见，天空也很常见，至少对我们这些居住在波士顿或者波士顿周边的人来说是这样的。
You can even make out some stars in the sky.
你还可以数出天上有几颗星星。
In 2003, there was a blackout that affected large parts of the United States and Canada, and Todd Carlson lost his electricity,
2003年，一场大规模停电影响了美国和加拿大大部分地区，托德·卡尔森家也停电了，
and he was smart enough to take a picture of his house at that time, and this is what it looked like.
那时他很聪明地又拍了一张房子的照片，它长这样。
And again, here you can see this strange, white cloud in the sky which is the Milky Way.
我再说一遍，你们看见的这朵奇怪的白云就是银河。
The lights that we are producing as humans, due to our ingenuity, are wiping out,
这时我们这些聪明的人类发明的光线都已经不存在了，
basically, our view of these millions of stars in the sky.
我们可以看见天空中数百万颗星星。
So, if we think about that, this is certainly a shame,
如果我们认真思考这个问题，我们就会觉得耻辱，
because there are a few things that are more magnificent than a view of the night sky.
因为很少有比夜空更让人觉得壮丽的东西。
But we should also think about what is this doing to our health if we're flooding ourselves with this amount of light pollution?
但我们也应该思考，我们的身体被暴露在这样大量的光污染中，会对我们的身体有什么影响？
So I want to I tell you that all throughout your bodies, in all of your organs, you have biological clocks
我想说在我们的身体的每个器官中，都有生物钟的存在，
that keep you in sync with the light-dark cycles of your environment that result from the Earth's rotation.
它们让你的身体可以跟由于地球自转导致的日夜循环保持一致。
And in your heads you have a master clock, a main clock that synchronizes all of these other clocks in your bodies.
你的大脑中也有一个控制时钟，它控制你身体各器官中的时钟好让他们同步。
The way that this works is that light travels from a source, such as the Sun, or an artificial light source,
这个过程的逻辑是光从源点出发，比如太阳，或某个人造光源，
through your eyes, and that light information is then conveyed to the brain,
到达你的眼睛，光线的信息传达到你的大脑，
to the master clock that's in a part of your brain called the suprachiasmatic nucleus, or the SCN.
再到你脑中的控制时钟，我们叫它超细胞核，或者SCN。
So in your eyes you of course have cells that help you see the stars, that help you form visible imagery.
你眼睛里的细胞帮助你看见星星，形成视觉影像。
But you also have cells that are not a part of the visual-forming pathways,
你身上还有一部分细胞不是用来形成视觉影像的，
but rather their role is to capture light information and basically convey it to the brain,
他们帮你捕捉到光线信息然后传输给大脑，
to tell the brain what time of day it is.
告诉大脑现在是一天的什么时刻。
So, how can I convince you that you have this clock?
那么我怎样说服你身体里有生物钟呢？
Well, if I closed you in a dark room where you would have no external source of light,
如果把你关在一个没有任何光源的房间里，
no alarm clocks, no clocks of any kind,
里面没有闹钟，也没有任何时钟，
you would still retain rhythmic sleep and wake patterns at least for a little while,
在至少一段时间内你还是会保持规律的沉睡和清醒模式，
because your clock was previously trained to light-dark cycles
因为你的生物钟曾被调节的与日夜循环相匹配，
and one of the main functions of the clock is to regulate behavioral rhythmicity.
而它的主要功能之一就是控制行为节奏。
This, of course, is not an experiment that many of you would be willing to subject yourselves to,
当然你们大部分人也不愿意参与这个实验，
but, fortunately, there's an experiment that most of us have participated in, which is traveling across time zones.
但幸运的是，有一个大部分人都愿意参与的实验，就是穿越时空。
So, I like this quote that says, "When you travel from America to Europe, your soul takes about three days longer to get there."
我很喜欢的一句话是这样说的：“从美国到欧洲，你的灵魂需要多花大概三天才能抵达。”
And I know this is certainly true when I travel from here to Serbia, my home country.
当我从这里回到我的祖国塞尔维亚的时候，我意识到这是对的。
It does take me several days basically, to feel normal, to feel aligned with the population that's living there.
我真的花了好几天才适应那里的正常生活，融入当地的居民。
And this is because your clock takes a few days to get realigned with this new schedule.
这是因为你的生物钟需要花几天时间来适应新的时间表。
And, if you think about this, this makes sense, right?
仔细想一想，确实说得通，不是吗？
So, for pretty much all of our history, except for a blink of an eye, in our evolutionary history,
在人类进化史上的几乎所有时间里，除了一眨眼的时间，
nobody had a way of hopping from one continent to the other in a matter of hours.
没有人可以在几个小时内从一个大洲跳到另一个大洲。
We're changing time zones so quickly, and in this case, nature's not really keeping up with what we are capable of doing.
我们时区切换的太快，因此自然界没能跟上我们的速度。
So, what is this clock? And why is it important to think about light?
那么这个钟是什么呢？为什么光线这么重要？
The clock is a molecular oscillator, the details here are not important at all,
其实它是一个分子振荡器，细节并不重要，
I don't want you to look at the names of these things on the board,
我不希望你们从黑板上认识这些名字，
but I want to point out that the clock is essentially the same in animals
我想说的是这些生物钟在动物体内也是一样的，
such as fruit flies, which my lab uses in our studies, and in mammals like mice or humans.
比如我实验室在研究中使用的果蝇，以及老鼠和人类这样的哺乳动物。
And the first glimpses of the clock, the components of the clock, and the way that it ticks were gained in the fly, actually.
同样的，果蝇体内这些生物钟的样子，组成部分，走动的方式也是一样的。
What I want to stress here is that the clock is tuned by light.
我想强调的是生物钟是由光线调节的。
Some of the components of this clock are actually degraded, directly degraded by light.
它们的组成部分实际上是直接由光线控制的。
So, that results in the state of the clock essentially oscillating throughout the day and night.
于是生物钟在白天和晚上就会震荡。
You can imagine if the composition of the clock, if some of the components are degraded,
你可以想象一下，如果生物钟的组成，如果生物钟一些组件退化了，
the composition of the clock will change between day and night.
那么生物钟的某个组成部分白天和夜晚就会发生变化。
And then the outputs of the clock between day and night will be different.
因此它产生的结果就是不同的。
So, for instance, during the day, the state of your clock is such that you are suppressing production of melatonin,
比如，白天你的生物钟会减少褪黑素的分泌，
which is the hormone that helps you fall asleep,
褪黑素就是帮助你入睡的荷尔蒙，
but also has other functions, such as anti-cancer and antioxidant properties.
它也有别的功能，比如预防癌症以及抗氧化。
So light. Let's talk about blue light a little bit.
我们再来聊聊蓝光。
When you're outside during the day, you're, of course, exposed to sunlight which consists of different wavelengths of light.
白天如果你外出，你会暴露在波长不同的光下。
But the one that's particularly important is blue light, because of its effect on our clock.
其中有中很重要的光叫蓝光，因为它会影响我们的生物钟。
Blue light also directly elevates your mood, it boosts your attention and your alertness.
蓝光还会调节我们的情绪，提高你的注意力和敏感程度。
So blue light during the day is very, very good,
白天的蓝光非常好，
and I'd say that most of us don't spend enough time in a bright light outside.
我们中的大部分人白天没有接触足够多的光线。
You should be for 30 to 60 minutes outside in bright light, so put some sunscreen on and go outside.
每天我们应该接触30-60分钟左右的光照，建议大家可以带上太阳光板或者多外出。
The flip side of this is that when you come home at night
它的负面影响就是晚上你们回家后，
I would dare guess that pretty much none of us spend the rest of the day when we come home,
我大胆猜测你们回家后并不是一天的结束，
in darkness, and we're not in tune with the natural light and dark cycles, right?
晚上我们就无法接受自然光暗循环周期的调节，对吧？
So, what we do normally is we use our computers, smartphones, tablets;
所以我们通常会使用电脑、智能手机、平板；
we are in rooms that have high amounts of LED light.
我们待在有很多LED灯的空间中。
And, in particular, what's really bad is that these devices are very, very rich in blue light.
这样做特别不好的一点是，我们会接触到非常非常多的蓝光。
So, what you're doing, every evening, when you're using these devices
所以每天晚上你使用这些东西的时候，
is you're essentially tricking your clock into thinking that it's still day.
就是在欺骗你的生物钟，让它觉得现在还是白天。
And since the clock during day and blue light suppress melatonin production, you're essentially doing that at night.
而白天的生物钟和蓝光会抑制褪黑素的分泌，这就是用这些东西的后果。
Now, I'm not naive enough to suggest you never use your computer at night, I know I wouldn't abide by that.
当然我不会天真到建议你们不要在晚上用这些东西，我知道我自己也做不到。
But one thing that you can do, is you can turn the brightness of your screen in the evening,
但是你可以做到的一件事情是，在晚上你可以调节屏幕亮度，
you can download programs that filter some of the blue light or you can use glasses that block some of the blue light.
可以下载些应用帮忙过滤掉一些蓝光，或者你可以戴上眼镜阻拦一部分蓝光。
I have a little bit of news for you that maybe you'll perceive as bad,
我有些事情想说，可能你们会觉得是坏事，
but I think it's actually very good, which is that you are very much like these guys.
但我觉得这其实是好事，我想说你们其实跟这些很像。
So, this is a close-up of a fruit fly, and you may not like if I tell you that you are like these guys.
这是果蝇的一张近照，我说你们跟它很像可能会让你们不开心。
But think about it for a second, this is very good for us
但是想想看，这其实是很好的，
because now we can use these animals as a model system to understand more about sleep biology,
因为我们现在可以用这些动物做模型来更好地理解睡眠科学，
and how light influences our clock and our health, and this is what my lab is doing.
以及光线是如何影响我们的生物钟和健康的，这就是我的实验室正在研究的。
So, they sleep just like we do, they sleep at night.
它们跟我们一样，在夜间休息。
If we deprive them of sleep, then they crash the next day during the time they would normally be active.
如果不让它们晚上休息，那么在第二天白天它们本该活跃的时间段，就会很萎靡。
If we deprive them of sleep for a long time, they die; so sleep is very important for them.
如果长期剥夺它们的睡眠，它们会死亡；所以睡眠对它们是很重要的。
The same genes that regulate sleep in humans regulate sleep in flies.
调节人类睡眠的基因同样会调节果蝇的睡眠。
And when they're asleep they're disconnected,
当它们沉睡后，就会和外界环境失去联系，
at least to a large degree, disconnected from their environment, just like we are.
至少在很大程度上会失去联系，就跟我们一样。
So, if these guys are sleeping, you need a stronger intensity stimulus to get them to react than when they're awake.
所以当这些生物睡着后，相比它们清醒着的时刻，你需要施加更强烈的刺激才能让他们做出反应。
So same thing that happens to you of course, when you're asleep.
同样的事情当然也会发生在你们睡着后。
Two people in my lab: a postdoc, Iris Titos Vivancos and a PhD student, Michelle Frank, are asking exactly
我实验室的两个人，博士后艾里斯·蒂托斯·维万科斯和博士生米歇尔·弗兰克，正在研究
what is this barrier that's established in the brain that prevents sensor information from coming through during sleep?
大脑中人睡着后阻拦感官信息通过的障碍到底是什么。
How can your same physical brain exist in two fundamentally different states?
不同的状态下人大脑的结构怎么会是一样的？
So now we're engaged, for instance, here I'm speaking to you, I'm engaged,
比如现在，我们在一起，我在演讲，
I'm aware of you, of my surroundings, I'm aware of my internal state;
我感知到你们，感知到周围的环境，感知到我的身体内部，
but tonight when I go to sleep, I will be in a completely different state.
但是今晚我睡着后，我会是在完全不同的一个状态。
And another thing that we're asking which is relevant to what I talked about, to light,
我们要问的跟主题光线相关的另一件事情是，
is how light coming through the eye is regulating sleep and wake patterns?
进入我们眼睛的光线是如何调节我们睡眠和清醒状态的？
A PhD student in my lab, Bryan Song, is asking exactly this.
我实验室的一位博士生，布莱恩·宋，就提出了这个问题。
What Bryan can do is, he can
他能做的就是，
you can see that flies have these big eyes that take up a large part of their head.
大家可以看见果蝇的眼睛很大，占据了它们整个头的一大部分。
What Bryan can do is he can actually trick the cells in the eye into thinking they're seeing light, even when they're not.
布莱恩所做的就是欺骗果蝇眼里的细胞，让他们认为自己看见了光线，其实根本没有。
And this results in animals having trouble falling asleep,
这就导致动物难以入睡，
so it takes them about an hour and a half longer to fall asleep.
它们要多花一个半小时才能睡着。
You can imagine that now we can use this as a model organism
我们可以用这个做器官模型，
to understand what it is that happens in the brain when it's getting light information
去理解接收到光线信息后大脑发生的变化，
and how this is interfacing with sleep and wake centers in the brain.
以及光线信号是如何干涉大脑的睡眠与清醒状态的。
And so one final thing I want to tell you is well,
最后我想说的是，
first I want you to think again for a moment about our evolutionary history.
我想请大家再想一想我们的进化史。
We evolved without alarm clocks, without any external source of information of the time of day,
我们曾经没有闹钟，曾经没有任何外界信息提醒我们现在是一天中的什么时刻，
and we've developed this way that keeps us in sync with our environment.
我们逐渐有了方法可以和环境同步。
But what we're exposing ourselves to every day now is very much interfering with that natural system,
但我们现在每天接触的东西很干扰这套自然系统，
and I think it's really something to think about.
我觉得这真的很值得思考。
So when people tell you that too much light exposure at night is not good, unfortunately, they are actually right.
所以当有人告诉你晚上接触太多光照不好的时候，很遗憾，实际上他们说的是对的。
And the last thing I want to say is please support basic science,
最后我想说，请支持基础科学，
because this is important for all of us, and this is the way forward, I think.
因为它对我们所有人都很重要，也是我们前进的方向。
