时差N小时 我们为什么要睡觉?(上)（在线收听）

It's such a commonplace event that you probably never asked yourself why you sleep.

睡觉是个特别自然的事儿，你大概从来没有问过自己为什么会睡觉。

But from a scientific point of view, this is far from a mundane matter --

但是从科学的角度来看，这是很神秘的一件事。

in fact, for sleep researchers, it's one of the biggest unanswered questions in the field.

而事实上，对于睡眠研究人员来说，这仍是该领域中一个悬而未决的问题。

Stop and think about it for a second. Why should we sleep? Is it because we get tired?

停下来仔细想想。我们为什么会睡觉?是因为我们累了吗?

But we sleep every night, even when we have had plenty of rest.

但是即使我们休息够了，晚上还是要睡觉。

Further more, if you were designing an animal, would you have it lapse into prolonged periods of unconsciousness every twenty-four hours?

此外，如果让你设计一种动物，你会让它每24小时陷入无意识状态一段时间吗?

Shouldn't that put it at a terrible disadvantage?

那不是让它处于很大的劣势吗?

There are no doubt several different answers to this question, but let's just consider one overall purpose sleep may fulfill:

毫无疑问针对于这个问题会有很多不同的答案，但我们单去考虑一个能够实现的整体目标：

sleep as a survival strategy.

睡觉是一种生存策略。

Human beings are "diurnal" creatures.

人类都是白天活动的。

That means we are normally active during daylight hours, when our senses function most effectively.

那意味着我们通常是白天活动力比较强，那个时候我们的感官功能也是最有效率的。