It's a fact, every living thing needs sleep. If they are deprived of it, both animals and men die in a short time. Sleep is just as vital a function as breathing, drinking or eating. To glean, pick or hunt, the animal must indeed be in full possession of its physical resources, its reflexes and its memory. To remain efficient, it is imperative to recover. This documentary introduces us to animal species with very different habits that each depart in search of life-saving rest in an unpredictable environment. But all share their habitat with inevitable neighbors, who do not necessarily intend to sleep at the same time. Indonesia's Sumatra Rainforest is like an urban mega-city that never sleeps, and every night some go to bed while others get up.

How to do when one is deprived of shelter to protect oneself? To fall asleep is to put oneself in a state of great vulnerability. And to each species the right strategy to sleep without perishing.