Stages of Sleep
Sleep stages are divided into non–rapid eye movement (non-REM) and rapid eye movement (REM).
Non-REM (NREM) sleep
Non–rapid eye movement (NREM) sleep has 3 stages:
REM (R) sleep
Rapid eye movement sleep is deeper than non-REM sleep. During REM sleep:
You do most of your dreaming during REM sleep. But your brain paralyzes your muscles so you do not act out the dreams.
During sleep, a person usually progresses through the 3 stages of non-REM sleep before entering REM sleep. This takes about 1 to 2 hours after falling asleep. The cycle is repeated three to four times each night. And adult spends more time in NREM sleep than in REM sleep. An infant usually spends about half of the sleeping time in NREM and half in REM stages.
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