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