Light and the circadian rhythm: The key to a good night's sleep？

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The cycle of sleep and wakefulness is one of the key human behaviours.

睡眠和觉醒的循环是人类的关键行为之一。

We spend about a third of our lives asleep and cannot survive without it.

我们我们大约有三分之一的生命睡着了，没有它就无法生存。

When asleep, our brain memorises and processes information. Our body clears toxins and repairs itself, allowing us to function properly when awake.

睡着时，我们的大脑会记住并处理信息。我们的身体清除毒素并自我修复，使我们在清醒时能够正常运作。

Even short-term sleep deprivation significantly affects our wellbeing. Most of us begin to fall apart after just one night without sleep and after three nights of missed sleep, we are functioning way below par.

即使短期睡眠剥夺也会严重影响我们的健康。我们大多数人在没有睡眠的一个晚上开始分崩离析，经过三个晚上的睡眠，我们的功能低于标准。

One study suggested that after 17-19 hours of staying awake, performance on cognitive tasks may be similar to having had too much to drink.

一项研究表明，17-19小时后保持清醒，认知任务的表现可能类似于喝太多酒。

These effects worsen over time. The longest documented period without sleep of just more than 11 days prompted serious cognitive and behavioural changes, problems with concentration and short term memory, paranoia and hallucinations.

这些影响随着时间的推移而恶化。记录最长的一段时间没有睡眠超过11天，导致严重的认知和行为改变，注意力集中和短期记忆，偏执和幻觉问题。

But while scientists have long understood the importance of getting enough sleep, the key part played by light exposure can sometimes be overlooked.

但科学家早就知道了充足睡眠的重要性，有时可以忽略曝光所扮演的关键角色。

Setting the body clock

设定生物钟

The reason light is so important is that it sets our circadian rhythm, or body clock, via specialised light sensors within the eye.

光是如此重要的原因是它通过眼内的专门光传感器设定我们的昼夜节律或身体时钟。

Our eye detects the light and dark cycle within our environment and adjusts the body's circadian rhythm so that the internal and external day coincide.

我们的眼睛检测到我们环境中的明暗周期和调整身体的昼夜节律，使内部和外部的日子重合。

This is so powerful that that people who have very severe eye damage can find their body clock is thrown off, leading to sleep problems.

这是如此强大，以至于眼睛受到严重伤害的人可以发现他们的生物钟被甩掉，导致睡觉问题。

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Without any access to light, the human body clock appears to drift, adding about half an hour on to its 24 hour cycle for each day of darkness.

没有任何光线，人体时钟似乎漂移，增加了约半小时每天黑暗的24小时循环。

Jetlag is the most obvious example of the effect light can have. Exposure to light in the new time zone helps reset our body clock to local time, telling us the right time to sleep.

Jetlag是光效最明显的例子。在新时区曝光有助于将我们的生物钟重置为当地时间，告诉我们适当的睡眠时间。

In 1800, most people across the world worked outside and were exposed to the change from day to night.

180，世界上大多数人都在外面工作，并且从白天到夜晚都接触到这种变化。

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  睡眠神话'损害你的健康'{/ p>

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  '猫头鹰'和'百灵鸟'的大脑不同 - 研究

Today, many of us miss out on these environmental cues as we work inside. Agriculture and fishing, for example, now make up just 1% of jobs in the UK.

今天，我们很多人在工作时错过了这些环境线索。例如，农业和渔业现在只占英国就业岗位的1％。

We have become a light deprived species, and this has far reaching consequences for the quality of our sleep, and consequently our wellbeing. The optimum amount varies from person to person, but we do know that our bodies need exposure to very bright light that the majority of indoor lighting does not provide.

我们已经成为一个淡贫的物种，这对其质量有着深远的影响。我们的睡眠，因此我们的幸福。最佳用量因人而异，但我们知道我们的身体需要接触大部分室内照明所不能提供的非常明亮的光线。

One notable side effect is Seasonal Affective Disorder (SAD), a form of depression thought to affect 2-8% of Europeans, which is linked to lack of sunlight exposure.

一个值得注意的副作用是季节性情感障碍（SAD），一种抑郁症，被认为会影响2-8％的欧洲人，这与缺乏阳光照射有关。

And there are many other areas where lack of natural light has caused problems.

还有很多其他方面的地方缺乏自然光导致了问题。

Working the nightshift

夜班工作

While many of us aren't getting enough natural light, for nightshift workers it is a particular issue.

虽然我们中的许多人没有获得足够的自然光线，夜班工人这是一个特殊的问题。

They have to work at a time when the body clock has prepared the body for sleep, and alertness and performance ability are low. They may try to make up on sleep during the day, but it will usually be shorter and of poorer quality.

他们必须在身体时钟为身体准备睡眠，警觉性和表现能力低的时候工作。他们可能会在白天尝试弥补睡眠，但通常会更短，质量更差。

In effect, they work when they are sleepy and sleep when they are not, and the negative health effects of this are only just being fully realised.

实际上，他们在困倦时工作，在他们睡觉时睡觉不是，这对健康的负面影响才刚刚完全实现。

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In the short term, it can prompt abnormal emotional responses and an inability to process information correctly.

在短期内，它可能会引发异常的情绪反应

Over the long term, many aspects of health can be affected by nightshift working, which may shorten life spans by up to six years.

从长远来看，健康的许多方面都会受到夜班工作的影响，这可能会缩短寿命长达六年。 p>

As many as 97% of nightshift workers fail to adapt to the demands of their work pattern, regardless of how many years they have been doing the job.

多达97％的夜班工人无法适应他们工作模式的要求，无论他们做了多少年的工作。{/ p>

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They are unable to shift their biology because the artificial light found in an office or factory is very dim compared to environmental light; by noon on a sunny day, natural light can be 250 times brighter than the light in an office.

他们由于在办公室或工厂发现的人造光与环境光相比非常暗淡，所以无法改变生物学;在晴朗的一天中午，自然光可以比办公室里的灯光亮250倍。

When a night shift worker leaves to go home they are often exposed to this bright natural light, sending signals to their internal timing system that it is time to wake up.

当一个夜班工人离开回家时，他们常常暴露在光明之下自然光，向他们的内部计时系统发送信号，是时候醒来了。

In a Harvard study, night shift workers became completely nocturnal after being exposed to bright light in the workplace and then totally shielded from natural light during the day. But this is not a practical solution for most people.

在哈佛的一项研究中，夜班工作人员在暴露在明亮的光线下后变得完全夜间活动。工作场所，然后在白天完全避开自然光。但对大多数人来说这不是一个实用的解决方案。

Natural light boost

自然光照增强

Nursing home residents also often suffer from lack of sunlight.

养老院居民也经常遭受缺乏阳光的困扰。

Indoor light can be dim while residents often experience very little natural light, meaning poor quality sleep is a common complaint.

室内灯光昏暗，而居民经常会感受到很少的自然光线，这意味着睡眠质量低是常见的抱怨。

A Dutch study increased the light in the communal areas of a nursing home, while attempting to make bedrooms as dark as possible.

荷兰的一项研究增加了养老院公共区域的光线，同时试图让卧室尽可能地变暗。

This appeared to reduce daytime napping and stabilise night-time sleep, which improved mental ability and sense of wellbeing.

这似乎可以减少白天午睡并稳定夜间睡眠这提高了心智能力和幸福感。

Sleep-deprived students

睡眠 - 贫困学生

Light deprivation is not just about the loss of bright natural light; it is also about the timing of light exposure.

光的剥夺不只是失去明亮的自然光;它也与曝光的时间有关。

Dusk light delays our body clock, making us get up later the next day. Morning light advances the clock, which makes us get up earlier.

黄昏光延迟了我们的生物钟，使我们第二天晚些时候起床。晨光推动了时钟，这让我们早起。

When we worked outside this was not a problem; we were exposed to both dawn and dusk and so the two cancelled each other out.

当我们在外面工作时，这不是问题;我们暴露在黎明和黄昏之间，所以两人互相取消了。

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But today many of us only experience part of the dawn-dusk cycle. This can be particularly true for university students, who tend to start the day later, and then spend more time outside in the early evening.

但今天我们很多人只经历了黎明 - 黄昏周期的一部分。对于大学生来说尤其如此，他们往往会在一天之后开始，然后在傍晚时间在外面度过更多时间。

The dusk light delays their body clocks, meaning they are likely to get up and go to bed later. This is compounded by hormonal changes in adolescence and early adulthood which delay the body clock by about two hours.

黄昏的灯光延迟了他们的生物钟，意思是他们很可能起床后再去睡觉。青春期和成年早期的荷尔蒙变化加剧了这种情况，使得生物钟延迟了大约两个小时。

The health consequences of smoking, alcohol and unprotected sex are well publicised, but the importance of sleep and the critical role played by light is arguably less well known.

吸烟，酗酒和无保护性行为的健康后果得到了很好的宣传，但是睡眠的重要性和光所起的关键作用可以说是不太为人所知。

Further research and greater awareness in this area could help individuals to make informed choices about prioritising their own sleep and getting enough sunlight. It could also influence the way that policies are developed by governments, educational institutions and workplaces.

在这方面进一步研究和提高认识可以帮助个人做出明智的选择，优先考虑自己的睡眠和获得足够的阳光。它还可能影响政府，教育机构和工作场所制定政策的方式。

Minimising light exposure before you go to bed, and trying to get us much morning light as possible, are simple steps that could help most people to regulate and improve their sleep.

在睡觉前尽量减少光线照射，尽量让我们尽可能早晨照亮，这是一个简单的步骤，可以帮助大多数人调节和改善他们的睡眠。

About this piece

关于这件作品

Russell Foster is a fellow of the Royal Society and the Academy of Medical Sciences. He is also a professor of Circadian Neuroscience and the head of the Nuffield Laboratory of Ophthalmology, which is part of the University of Oxford.

罗素福斯特是皇家学会和医学科学院的研究员。他还是昼夜神经科学教授和纳菲尔德眼科实验室主任，该实验室是牛津大学的一部分。