Rapid eye movement sleep. This is the time of vivid dreaming.
A phase of sleep during which the eyes move quickly (REM stands for “rapid eye movement), heartbeat and metabolism speed up, and toes and fingers twitch. Dreaming takes place during REM sleep.
The acronym for rapid eye movement sleep, the sleep phase characterized by increased brain activity and the occurrence of dreams. REM sleep alternates with non-rapid eye movement (NREM) sleep throughout the night.