REMslaap

REMslaap, or rapid eye movement sleep, is a distinct stage of sleep observed in humans and other mammals. It is characterized by rapid eye movements, pronounced brain activity similar to wakefulness, and a notable reduction in muscle tone (atonia). Dreams are commonly reported during this stage, though not exclusively. REM sleep alternates with non-REM sleep throughout the night.

REM slaap occurs in cycles roughly every 90 to 120 minutes. The first REM period typically appears about 70 to 90 minutes after sleep onset and tends to lengthen with each cycle. In healthy adults, REM sleep accounts for about 20–25% of total sleep, equating to roughly 90 to 120 minutes per night. Newborns and infants spend a larger proportion of sleep in REM.

Physiologically, REM sleep shows low-amplitude, mixed-frequency EEG activity with occasional sawtooth patterns, rapid eye movements (EOG), and almost complete muscle atonia (EMG). Autonomic activity is variable, with fluctuations in heart rate, blood pressure, and breathing. Phasic bursts of activity called PGO waves may accompany REM sleep, and autonomic and cortical activity resemble wakefulness more closely than other sleep stages.

Functions attributed to REM sleep include involvement in memory consolidation, emotional processing, and neural plasticity. REM is also important for brain development in infants and appears to support learning and adaptation in adults. The exact mechanisms and scope of these functions remain active areas of research.

Clinical aspects include REM sleep behavior disorder, in which atonia is incomplete and dream-enacting movements may occur. REM sleep can be influenced by medications and disorders that alter sleep architecture, and REM characteristics are commonly assessed using polysomnography in clinical settings.