Non-rapid eye movement sleep; Non-REM sleep
Non-rapid eye movement sleep (NREM), also known as quiescent sleep, is, collectively, sleep stages 1–3, previously known as stages 1–4. Rapid eye movement sleep (REM) is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement during these stages.
from Wikipedia
睡眠段階
Awake
Rapid Eye Movement sleep; REM sleep
Non-rapid eye movement sleep; Non-REM sleep
Stage1
Stage2
Stage3(Slow Wave Sleep; SWS)