REM cycles
Dreaming sleep phases
REM cycles are the recurring periods of rapid eye movement sleep that occur throughout the night, typically every 90 minutes or so.
During REM sleep, the eyes move quickly beneath closed lids, dreams are most vivid, and the brain is highly active while the body remains largely paralyzed.
Each cycle grows longer toward morning.
I woke up between REM cycles and couldn't fall back asleep.
- sleep stagesDistinct periods during rest
- dreamSleeping mind's narrative
- dream stateConsciousness during sleep
- acetylcholineNeurotransmitter for muscles and memory
- sleep paralysisTemporary waking immobility
narcolepsy · hypersomnia · sleep study · brain waves · atonia · circadian rhythm · lucid dreaming · sleep spindles · pons · dream recall · melatonin · body temperature · emotional processing · snoring · limbic system · insomnia · sleep deprivation · falling asleep
- Brain MeasuresEEG, fMRI, MRI images, brain scan, brain scans
REM cyclesnon-REM sleep
Restful phase without dreaming
deep sleep · light sleep · restorative sleep · dreamless sleep
REM cycleswakefulness
State of being conscious
arousal · vigilance · coma · unconsciousness