What Happens When You Sleep?

It may seem as though your body shuts off completely while you're asleep.This is not totally off the track,because your breathing and heart rate do slow down temperature drop slightly.But at the same time,your brain continues to recognize outside information,so it remains about as active,in a different way, as it is when you're awake.
         It exhibits this activity in the form of brain waves,or electrical changes that take place waves,scientists have been able to recognize the different stages of sleep,and what goes on in the brain during each phase.