Sleep: how much do you really get?

It’s likely you have no real clue how much sleep you got last night, or how sleep-deprived you are right nowFew things better illustrate how little we understand ourselves than the mysteries of sleep. For a start, there’s the big mystery of why we do it in the first place, since in evolutionary terms, being unconscious for a third of every day is one of the most suicidal strategies imaginable. (This means that whatever sleep’s for, it must be really important to make it wo