At Stanford University I visited William Dement, the retired dean of sleep studies, a co-discoverer of REM sleep, and co-founder of the Stanford Sleep Medicine Center. I asked him to tell me what he knew, after 50 years of research, about the reason we sleep. “As far as I know,” he answered, “the only reason we need to sleep that is really, really solid is because we get sleepy.”
Sleep has always phased me. Why do some people need to sleep all the time, while others hardly at all? Why do all animals, including us, need to sleep when it leaves us exposed at our weakest? It seems there aren’t any easy answers.