Here’s what to know about the twice yearly ritual. The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when ...

The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when we become sleepy and when we’re more alert.

Sleep deprivation can occur after just 24 hours of no sleep. However, the longer you spend awake, the more severe — and less tolerable — symptoms become. Share on Pinterest For most people ...