What happens in each sleep stage?

Light sleep: During light sleep, your brain transitions from wakefulness to sleep. Your breathing and heart rate become regular and your body temperature drops. During this stage, you are somewhat alert and can easily be woken.

Deep sleep: In deep sleep, your body is less responsive to your surroundings. Your breathing slows down and your muscles are more relaxed. It is more difficult to wake up during this stage. This is when most of your body’s muscle and tissue repair takes place, growth and development are stimulated, immune function is boosted, and energy is restored for the next day.

REM sleep: While you are in REM sleep, your eyes move rapidly in various directions and your body is relaxed and immobile. Most dreams occur during REM sleep. This stage is thought to be important for learning and memory, since this is when your brain consolidates and processes information gathered while you were awake so that it can be stored in your long-term memory.

Awake: An awakening of more than five minutes is classified as awake, and is not included in your total sleep time.