REMsömn

REMsömn, or rapid eye movement sleep, is a sleep stage characterized by rapid eye movements, desynchronized EEG activity resembling wakefulness, reduced muscle tone (atonia), and frequent dreaming. It typically occurs in cycles throughout the night, often becoming longer toward the morning.

Physiologically, REM sleep is generated by brainstem circuits in the pons that activate cortical networks while motor neurons are inhibited. Eye movements arise from bursts of activity in the extraocular muscles. Autonomic changes, such as fluctuations in heart rate and respiration, accompany REM sleep, and the EEG shows low-amplitude, mixed-frequency activity with bursts of rapid eye movements.

The functions of REM sleep are a topic of ongoing research. It is associated with memory consolidation, particularly for emotional and procedural memories, and with mood regulation. REM sleep also supports brain development in early life, and may contribute to dream generation. The exact mechanisms remain debated.

Clinical relevance includes REM sleep behavior disorder, in which the usual muscle atonia is reduced or absent, allowing dream enactment. Other conditions, such as narcolepsy, can feature REM-related phenomena including sleep-onset REM periods. Disruption of REM sleep can affect cognitive performance and mood.

History and measurement: REM sleep was first described in 1953 by researchers Eugene Aserinsky and Nathaniel Kleitman. It is diagnosed and studied using polysomnography, which records EEG, electro-oculography (EOG), and electromyography (EMG).