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 snooze. One study reveals that well-timed bursts of pink noise can nudge a person's brain waves, extending periods of slow-wave, or deep, sleep. And toddlers learning new words show that taking even a short nap after learning something new can help the information stick. And when it comes to sleeping poorly, it may turn out that having interrupted sleep can be just as harmful as missing sleep altogether. As scientists come to understand the powerful role that sleep -- or lack of it -- plays in everything from memory to trauma to emotion regulation, one thing is clear: This biological function is as crucial as it is complex.
A documentary on the areas affected by Hurricane Katrina.
01末日预言The Doomsday Prophecies 02玛雅人的阴谋The Mayan Conspiracy 03小灰人The Greys 04外星人与大灾变Aliens and Mega-Disasters 05与美国太空总署的联系The NASA Connection 06普马彭古的秘密The Mystery of Puma Punku 07外星人和大脚怪Aliens and Bigfoot 08达芬奇阴谋The Da Vinci Conspiracy 09时间旅行者The Time Travelers 10外星人和恐龙Aliens and Dinosaurs