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 ...。Based on the best-selling novels from globally renowned author Peter James, series five will comprise of the following four films - Dead If You Don't, Dead At First Sight, Need You Dead and Find Them Dead.。