The Stages of Sleep

The Sleep Cycle

NREM sleep is itself divided into four different stages. The combination of these five stages (four NREM, one REM) creates a cycle that lasts around ninety minutes on average and repeats several times during the night.

At the end of each cycle many people actually wake up briefly. Most people don't even remember this, however some poor sleepers may wake fully.

NREM Sleep

NREM stage 2 represents the lightest stage of "real" sleep. The sleeper can be wakened but with more difficulty than in stage 1. Brain waves become larger and the body gradually shuts down. During NREM stage 2 sleep becomes slowly deeper until...

NREM stage 3 is the threshold to deep sleep. It usually occurs between thirty to fourty-five minutes after starting to sleep. In NREM stage 3 the sleeper is much more difficult to waken and the large, slower delta brainwaves are generated.

NREM stage 4 is "deep sleep". It is during deep sleep that the body gets its most rest and does its best repair work. A sleeper in deep sleep will be very difficult to awake - sleep walking (somnambulism) sometimes occurs during this stage.

The first deep sleep period of the night is the longest and the deepest. After the deep sleep period is over the sleeper reverses the pattern, moving back up to NREM stage 2 then entering REM sleep.

>>> Page 2 - REM Sleep >>>

IMPORTANT NOTE: This is not a medical site. You should always discuss medical matters with your doctor.