NOVA: Mysteries of Sleep Like virtually every other animal, humans need sleep to survive. But why? What do we gain from spending nearly a third of our lives in such a defenseless state? And what's at stake if we sleep poorly? The functions of sleep have long been something of a mystery. But now scientists are peering deep into the brain to see what happens while we snoo三米影视为您提供免费在线观看睡眠之谜在线观看(HD)，喜欢的话，不要忘记收藏本站网址哦！