Matthew Walker: My name is Matthew Walker. I am a professor of neuroscience and psychology at the University of California Berkeley and I am the author of the book, "Why We Sleep."

　　马修·沃克: 我叫马修·沃克。我是加州大学伯克利分校的神经科学和心理学教授，我是《为什么我们需要睡觉》这本书的作者。

　　Should we actually be taking naps during the day? Well, we certainly know from evidence in my own sleep center and that of many other scientists that naps can give you benefits for both your brain and your body. But naps can actually be a double-edged sword because whilst we’re awake during the day, we’re building up sleepiness or sleep pressure. So that when you try to fall asleep at night, you’ll fall asleep quickly and then you’ll stay asleep. And when we sleep, we actually release that sleepiness, almost like a valve on a pressure cooker, so that we wake up the next morning feeling refreshed.

　　我们真的有必要在白天打个盹吗?当然，我们从我自己的睡眠中心和其他许多科学家的研究中都知道，午睡能给你的大脑和你的身体带来好处。但打瞌睡实际上是一把双刃剑，因为当我们在白天醒着的时候，睡意和睡眠压力是不断累积的。所以当你试图在夜里入睡时，你很快就会睡着，并且睡得很好。当我们睡觉的时候，我们实际上释放了困倦，就像压力锅上的阀门一样，我们第二天早上醒来的时候会感觉焕然一新。

　　So if you take a nap during the day, especially if you take it too late in the afternoon, you will actually release some of that sleepiness and it will make it that much more difficult to fall asleep and stay asleep soundly throughout the night. So the advice would be if you don’t struggle with your sleep and you can nap regularly, then naps are just fine.

　　所以，如果你在白天打个盹，尤其是如果选择在下午晚些时候睡一会的话，你就会释放一些睡意，这会让你夜晚更难入睡，并且很难在整个晚上都保持着良好的睡眠。所以建议是，如果你不想与困意斗争的话，你可以有规律地小睡，使得小睡恰到好处。

　　But if you do find it difficult to fall asleep or stay asleep at night, then you should avoid naps and try and build up that healthy sleepiness in the evening.

　　但是如果你发现在晚上很难入睡或者晚上睡眠质量不佳，那么你应该避免小睡，并且在晚上尝试建立足够的睡意。

　　The ideal nap depends on what you want from that nap. Different stages of sleep actually give you different types of brain and body benefits.

　　理想的小睡取决于你想从小睡中得到什么。不同的睡眠阶段实际上会给大脑和身体带来不同的好处。

　　But if you want to avoid that grogginess that you can often have after a long sleep, then you should perhaps avoid naps that are longer than maybe 40 or 50 minutes in length.

　　但是，如果你想避免长时间睡眠后经常出现的那种恶心感，那么你应该避免超过40或50分钟的长时间小睡。

　　You should also try to avoid naps late in the afternoon so that you wake up at least after you finish the nap and still have enough time to build up that sleepiness, that sleep pressure so you can get to sleep in the evening.

　　你也应该尽量避免在下午晚些时候小睡，这样至少你在午睡之后醒来，还有足够的时间来提高睡眠质量，这样你就可以在晚上安然入睡了。

　　Can naps help with sleep debt?

　　打瞌睡能帮助偿还“睡眠债务”吗?

　　Walker: And the answer, unfortunately, is no. Sleep is actually not like the bank. You can’t accumulate a debt and then hope to pay it off at some later point in time. So sleep is an all-or-nothing event in that sense. So you can’t short sleep during the week and then try to binge and oversleep at the weekend.

　　沃克：不幸的是，答案是否定的。睡眠其实和银行不一样。你不能积累债务，然后希望在以后的某个时间点还清。所以在这个意义上睡眠是一件孤注一掷的事。所以你不能在一周内睡眠不足，然后尝试在周末狂欢并在周末睡过头。

　　So if I were to take a human being and deprive them of sleep for one night, so that they’ve lost eight hours of sleep and then I give them all of the recovery sleep that they want on a second, a third, even a fourth night, they do sleep longer but they never get back that full eight hours that they’ve lost.

　　如果我剥夺一个人的睡眠,这天晚上,他已经失去了八小时的睡眠,然后我在第二个,第三个,甚至第四个夜晚提供他们想要的所有的睡眠,他们可以睡很长时间,但他们再也找不回失去的睡眠了,整整八个小时,他们已经失去了。

　　And we can ask then, "Why isn’t there some kind of a credit system in the brain? Why don’t we have a cell that can actually store up that sleep?"

　　我们可以这样问，“为什么大脑中没有某种信用系统?”为什么我们没有一个能储存这种睡眠的细胞呢?

　　Because there is precedent for this. We actually have a storage system for calories within in the body and they’re called, "fat cells." Because there was a time during the evolutionary process where we had feast and where we had famine. And when we had feast, we would store that caloric energy and fat cells that when we went into a debt during that caloric famine, we could actually survive.

　　因为这是有先例的。我们实际上在体内有一个储存卡路里的系统，它们被称为“脂肪细胞”。“因为在进化的过程中，我们有过盛宴，也有过饥荒。当我们享用盛宴的时候，我们有能量和脂肪细胞可以储存卡路里，当我们在卡路里饥荒中负债时，我们就能生存下来。

　　Human beings are the only species that deliberately deprive themselves of sleep for no apparent reason. And that means that Mother Nature has never had to face the challenge of sleep deprivation during the course of evolution and therefore, she’s never had to come up with a safety net mechanism that overcomes a sleep debt.

　　人类是唯一故意剥夺自己睡眠的物种。这意味着，大自然母亲在进化过程中从来没有遇到过睡眠剥夺的挑战，因此，她从来没有需要建立一个安全的机制来克服睡眠债。