You can live longer without food than without sleep. Missing one night’s sleep makes you crabby and clumsy. Two sleepless nights drain your brainpower; you have trouble thinking and doing things.
Five nights awake, and you hallucinate (see things that aren’t there). Death may be next: Your brain can’t maintain vital body functions. The official no-sleep record? Bertha van der Merwe of South Africa went without sleep for 11 days, 18 hours, and 55 minutes.
Why is sleep a nightly need? It’s a vacation for your body. But not for your brain. The brain works as hard at night as it does all day. Scientists aren’t sure exactly what it’s doing on the night shift. Replacing used-up chemicals? Filing, tossing, and organizing the day’s information? Solving problems? Whatever the nightly duties are, they keep you alive and well.