There are five stages of sleep; Stages 1-4, and then REM (rapid eye movement) sleep, in which dreaming occurs.
There are 4 non-REM stages and REM sleep.
first 2 hours of sleep light sleep middle hours 3- 5 deep sleep 1-3 hours light sleep
As of 2008, the American Society of Sleep Medicine combined the stages three and four. So now there are only 3 stages
quiet sleep
The deepest stage of sleep is REM or Rapid Eye Movement.
5 stages of grief 5 stages of grief 5 Stages of Grief
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1:Birth 2:Eat 3:Sleep 4:Sex 5:Sex 6:Death
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There is alpha or stage one sleep, theta or stage two sleep, delta or statge 3 sleep, and alpha with REM (stage 4 sleep).
Sleep stages are defined in terms of brainwave patterns, which can be measured by an electroencephalograph (EEG).