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: - Stage
N1 occurs right after you fall asleep and is very short (usually
less than 10 minutes). It involves light sleep from which you
can be awakened easily. - Stage N2 lasts from about 30 to 60
minutes. During this stage, your muscles become more relaxed and
you may begin to have slow-wave (delta) brain activity. It is
not easy to wake up a person in this stage of sleep. - Stage N3
is deep sleep and lasts about 20 to 40 minutes. During this
stage, delta brain activity increases and a person may have some
body movements. It is very hard to wake up someone in stage N3.
REM (R) sleep Rapid eye movement sleep is deeper than non-REM
sleep. During REM sleep: - The eyes and eyelids flutter. -
Breathing becomes irregular. During REM sleep, it is normal to
have short episodes when breathing stops (apnea). You do most of
your dreaming durin