During sleep, the body goes through multiple sleep cycles. Each cycle consists of four stages: three stages of non-rapid eye movement (non-REM) sleep and one stage of rapid eye movement (REM ...

We cycle through these stages several times throughout the night (see graphic). Non-REM sleep consists of three parts: falling asleep, light sleep and deep sleep. During this time, brain waves ...

Rapid eye movement (REM) sleep is one of four stages the brain moves through while sleeping. In REM sleep, the eyes move rapidly in various directions and dreams can occur. REM sleep typically ...

Need another reason to prioritize your sleep? Not spending enough time in the two deep stages of sleep — slow-wave and rapid eye movement, or REM, sleep — may hasten the deterioration of parts ...