Reconsidering "Sleep Paralysis" in Narcolepsy: Non-Identity of Hypnagogic REM Intrusion and Typical Isolated Sleep Paralysis

The term "sleep paralysis" in narcolepsy may not refer to the same neurophysiological state as typical isolated sleep paralysis in healthy individuals. Typical isolated sleep paralysis occurs upon awakening and involves residual REM-related muscle atonia without emotional triggering. In contrast, narcolepsy-related experiences labeled as sleep paralysis more often occur at sleep onset and are closely associated with hypnagogic hallucinations and cataplexy-like muscle atonia. Many such reports may represent a composite experience of REM intrusion at sleep onset rather than a direct increase in typical isolated sleep paralysis. The paper argues that the term should be used with explicit distinction regarding timing and the mode of muscle atonia.

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Abstract

This conceptual paper re-examines the commonly used term “sleep paralysis” in narcolepsy.Although narcolepsy is often described as being associated with frequent sleep paralysis,it remains unclear whether patient-reported experiences correspond to the sameneurophysiological state as typical isolated sleep paralysis observed in healthy individuals. This paper conceptually distinguishes two phenomena:(1) typical isolated sleep paralysis in healthy individuals, which predominantly occurs upon awakeningand can be interpreted as residual REM-related muscle atonia without emotional triggering, and(2) narcolepsy-related experiences labeled as “sleep paralysis,” which more often occur at sleep onsetand are closely associated with hypnagogic hallucinations and cataplexy-like muscle atonia. The analysis suggests that many reports of “sleep paralysis” in narcolepsy may represent a compositeexperience of REM intrusion at sleep onset rather than a direct increase in typical isolated sleep paralysis.Accordingly, the paper argues that the term “sleep paralysis” should be used with explicit distinctionregarding timing (sleep onset vs. awakening) and the mode of muscle atonia (emotion-triggered vs. residual).