One of the principal functions of rapid eye movement sleep that we now have understood is that it seems to provide a form of overnight therapy. REM sleep is emotional first aid. It's during REM sleep that we take the emotional concerns—and even sometimes, in extreme examples, some of the traumatic events that we've been experiencing—and REM sleep almost acts like a nocturnal soothing balm. It tries to take the sharp edges off those difficult experiences so that when you come back the next day, you don't necessarily feel as emotional as you did about those events the day before ... It's not time that heals all wounds; it's time during REM sleep and dreaming that provides this emotional convalescence.