The Secrets of Sleep Nova : Season 2 Episode 4

Most of us spend one-third of our lives in a state of which we understand remarkably little—some people sleep for only a few minutes a night, and function perfectly well, while others declare that eight hours isn't enough. NOVA explores traditional notions about how much sleep we need; looks at effects of the sleeping pill, and, perhaps the most baffling of all aspects of sleep—dreaming.