Medicine & Health
How does sleep work?
Sleep works as an active, cyclical process where the brain moves through stages — light sleep, deep sleep, and REM (dreaming) — several times a night. During sleep the body repairs itself and the brain consolidates memories and clears waste.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how sleep works.
Step by step
- 1The brain cycles through light, deep, and REM stages repeatedly.
- 2Deep sleep restores the body; REM supports memory and mood.
- 3A 'body clock' (circadian rhythm) times sleep using light and hormones.
- 4Too little sleep harms focus, mood, immunity, and health.
Frequently asked questions
- Why do we sleep?
- To repair the body, consolidate memories, regulate mood and hormones, and clear waste from the brain.
- What is REM sleep?
- A stage with vivid dreaming and high brain activity, important for memory and emotional processing.
- What is the circadian rhythm?
- Your internal ~24-hour clock that controls when you feel sleepy or awake, guided by light.