(Read about secrets of why we sleep in National Geographic magazine.)

(请参考国家地理杂志《睡眠的奥秘》一文)。

youdao

This explains why we sleep at all and this probably explains why we sleep at night.

这个解释了我们为什么要睡觉，这个解释了我们为什么在晚上睡觉。

youdao

Over the years, scientists have come up with a lot of ideas about why we sleep.

关于我们为什么要睡觉，多年来，科学家提出了很多想法。

youdao

why,when we do not sleep, we do not function well. We just do not know much about sleep at all."

VOA: special.2009.08.26

This explains why we sleep at all and this probably explains why we sleep at night.

这个解释了我们为什么要睡觉,这个解释了我们为什么在晚上睡觉。

耶鲁公开课 - 心理学导论课程节选

Why do we sleep and why don't we--why aren't we always awake?

我们为什么会睡觉,我们为什么不是一直醒着？

耶鲁公开课 - 心理学导论课程节选

One of the great riddles of sleep is why we do it.

NEWYORKER: Up All Night

"We aren't sure why activity primes your body for sleep so well, but it's likely a combination of factors, including lowering your core body temperature, increasing the sleep-promoting hormone melatonin and supporting a biological need to restore energy levels and repair cells and tissues when you sleep, " Cardinal says.

CNN: How to fix health problems with exercise

Monster and interrogated Husband as to why he would give Baby water on a night we desperately needed him to sleep.

FORBES: Tim Tebow, Soledad O'Brien and My Not So Pretty Balancing Act