Non-Rapid Eye Movement Sleep and Overlap Parasomnias

Purpose of Review: This article reviews the spectrum of non-rapid eye movement (non-REM) sleep parasomnias, including sleepwalking, confusional arousals, and sleep terrors, which represent the range of phenotypic disorders of arousal from non-REM sleep that occurs in children and adults. Recent Findings: The International Classification of Sleep Disorders, Third Edition (ICSD-3) classifies parasomnias according to the sleep stage they emerge from: REM, non-REM, or other. Demographics, clinical features, and diagnosis of non-REM parasomnias are reviewed in this article, and an up-to-date synopsis of guidelines for management strategies to assist in the treatment of these sleep disorders is provided. Summary: The non-REM parasomnias are most common in children and adolescents but may persist into adulthood. They can be distinguishable from REM parasomnias and nocturnal epilepsies, and, importantly, may lead to injury. Additionally, other parasomnias in this spectrum include sleep-related eating disorder and sexsomnia. Overlap parasomnia disorder includes one or more manifestations of a non-REM parasomnia seen in combination with REM sleep behavior disorder, representing an apparent erosion of the normally distinct stages of non-REM and REM sleep. A similar yet much more extreme dissociation of states underlies agrypnia excitata and status dissociatus, which represent rare, severe dissociations between non-REM, REM, and wake states resulting clinically in oneiric behaviors and severe derangement of normal polysomnographic wake and sleep stage characteristics. Management of non-REM and overlap parasomnias and state dissociation disorders include ensuring bedroom safety and prescription of clonazepam or hypnosis, in select cases, although in children and adolescents with noninjurious behaviors, non-REM parasomnias are often age-limited developmental disorders, which may ultimately remit by adulthood, and, in these cases, counseling and education alone may suffice. Timely and accurate recognition of the non-REM and overlap parasomnias is crucial to limiting potential patient injury.