There are some activities your body automatically continues whether you’re awake or asleep. Without them, you could not go on living. For example, your heart beats and you breathe; your blood continues to flow, bringing food and oxygen to all the cells in your body.
Sleep is also the time when those body cells that have worked hard all day and become worn out are repaired, replaced, and build up new supplies of energy for the following day. This is also the time when you grow the most.
During sleep, your brain, which pays attention to the outside world when you’re awake, now takes a rest. Your eyes close so that your brain does not get signals about things you see when you’re awake. Ordinary sounds also do not disturb you now. Your brain is still active to keep you alive, but you lose the sense of being yourself. This is called consciousness.
During an average 8-hour sleep, you change the position of your body at least twelve times!
