Definition
- REM sleep
- REM sleep is the stage of sleep characterised by rapid eye movement, heightened brain activity resembling wakefulness, and temporary muscle paralysis. Most vivid dreaming occurs during REM, and it is associated with memory consolidation and emotional processing.
Where it sits in the night
REM periods lengthen as the night goes on. The first REM period of the night may last only a few minutes; the last can run for close to an hour. Because REM is concentrated in the final hours of sleep, cutting a night short removes disproportionately more REM than deep sleep.
Waking during REM
Waking directly out of REM often produces vivid dream recall and, for some people, a brief disoriented feeling. It generally produces less severe sleep inertia than waking from deep sleep does.