- Sleep is started with non REM sleep.
- Sleep cycles of 90 minutes, 4-6 cycles per night sleep.
- Non-REM 3 predominates in the first third of the night and is linked to the initiation of sleep.
- REM sleep predominates in the last third of the night
- Wakefulness in sleep usually accounts for less than 5% of the night.
- Non-REM 1 sleep approximately 2% to 5% of sleep.
- Non-REM 2 sleep approximately 45% to 55% of sleep.
- Non-REM 3 sleep approximately 15% to 20% of sleep.
- Non REM sleep, therefore, is usually 75% to 80% of sleep.
- REM sleep is usually 20% to 25% of sleep, occurring in four to six episodes.
|Sleep stadium||Sleep pattern|
|Non-REM 1||Slow rolling eye movements (SREMs), decrease of alpha rhythm, POSTS (Positive occipital sharp transients of sleep), Vertex waves, theta activity|
|Non-REM 2||Sleep spindles, K complex, <20% Delta waves|
|Non-REM 3||>20% Delta waves|
|REM sleep||Low voltage background, rapid eye movements, muscle atonia|