Classification of Parasomnias

Abstract

Parasomnias, or undesirable events accompanying sleep, encompass a broad spectrum of behaviors and experiences. Classification of parasomnias has undergone a significant transformation in the International Classification of Sleep Disorders Third Edition. Underlying this new classification is the understanding that Wake, NREM sleep, and REM sleep are not mutually exclusive states. Recent advances in neuroscience support the State Dissociation paradigm which would allow for an unstable admixture of components of these states to coexist. Parasomnias are the clinical manifestation of this state instability. This article briefly reviews the characteristics, demographics, and pathophysiology of the core parasomnias and associated disorders, with emphasis on disorders of arousal and diagnosis and prognostic significance of REM sleep behavior disorder.