People from every part of the world, hippos in the jungle, fish in aquariums – they all sleep! Sleep is as important as breathing or eating. In fact, people can survive longer without food than they can without sleep.

Sleep is vital for giving your body a rest and allowing it to prepare for the next day. It’s like giving your body a mini-vacation. Sleep also gives your brain a chance to sort things out. Scientists aren’t exactly sure what kinds of organizing your brain does while you sleep, but they think that sleep may be the time when the brain sorts and stores information, replaces chemicals, and solves problems.

The amount of sleep a person needs depends a lot on his age. Babies sleep a whole lot – about 14 to 15 hours a day! But many older people only need about 7 or 8 hours of sleep a night. Most kids between the ages of five and 12 are somewhere in between – they sleep 10 -11 hours a night. But the amount of sleep a kid needs really depends on the kid: some find they need a little less sleep, some more.

Skipping one night’s sleep makes a person cranky and clumsy. After missing two nights of sleep, a person will have problems thinking and doing things; his brain and body can’t do their normal tasks nearly as well. After five nights without sleep, a person will hallucinate (this means seeing things that aren’t actually there). Eventually, it becomes impossible for the brain to give its directions to the rest of the body without sleep – the brain needs to spend time in bed and catch its zzzz’s!