English-Chinese/Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep

Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep.

睡眠发生在重复的时期，其中身体在两种不同的模式之间交替：REM睡眠和非REM睡眠.