What is light sleep, deep sleep, and REM sleep?

Light Sleep

• The least restorative of the sleep stages, but important because it often comprises up to half of total sleep. It's easiest to wake up during this stage of sleep. The body processes memories and emotions, and metabolism is regulated during light sleep. 

Deep Sleep

• During deep sleep, blood pressure drops, breathing may become slightly slower, and muscles are relaxed as tissue growth and repair occur, and energy is restored. A higher proportion of deep sleep typically occurs during the first half of the night. 

REM Sleep

• REM (rapid eye movement) sleep provides energy to the brain and body and supports daytime performance and cognition. Dreaming also occurs during REM sleep. A higher proportion of REM sleep typically occurs during the second half of the night.