What happens when you sleep?

The 5 phases of sleep

Phase 1

The base of your brain sends signals to the other areas of your brain that it’s time to stop making you feel awake and start powering down. You begin drifting in and out of sleep, and your eye and muscle activity starts to slow down.

Phase 2

At this point, you’re asleep. Your brain has told your eyes to stop moving and allows your body temperature to drop. Your brain waves start to slow down.

Phases 3 and 4

At this point, your brain signals your body to let your blood pressure drop, slow your breathing, and relax your muscles. Now your brain floods your body with growth hormones so that your body can get to work on tissue repair and muscle development.

Phase 5

This is the REM stage when your brain is at its most active and you have dreams. This phase gives your brain and body the energy boost you’ll need to get through the day tomorrow.

These five phases take somewhere between 90 and 110 minutes to run. Throughout the night, your brain will repeat this sleep cycle several times before morning.