Your brain is more active while you sleep than when you watch television.

In 1953, researchers Eugene Aserinsky and Nathaniel Kleitman discovered Rapid Eye Movement or REM sleep. They used a machine called an EEG to measure brain waves. They found that brain waves during REM sleep look almost exactly like the waves of a person who is wide awake.During this stage, the brain uses more energy than it does during many daytime tasks. Parts of the brain like the amygdala and hippocampus are very busy. These areas help you process feelings and store what you learned during the day.The brain also has a cleaning system called the glymphatic system. It becomes 10 times more active while you sleep. It pumps fluid through the brain to wash away waste products and toxic proteins. This process keeps the brain healthy and prevents diseases.To keep you safe during all this activity, your body enters a state called atonia. This is a temporary paralysis that stops your muscles from moving. It prevents you from acting out your dreams and accidentally hurting yourself while you rest.