parasomnia

Parasomnia refers to undesirable events or experiences that occur during sleep, during arousal from sleep, or during sleep-wake transitions. It includes a range of discrete disorders, often classified as non-REM arousal disorders (sleepwalking, sleep terrors, confusional arousals), REM-related disorders (REM sleep behavior disorder and nightmare disorder), and other parasomnias such as sleep-related eating, sexsomnia, sleep paralysis, and rhythmic movement disorders. Many parasomnias occur in otherwise healthy people, but they can also be associated with medical, neurologic, or psychiatric conditions.

Non-REM arousal disorders involve incomplete awakening with complex behaviors, amnesia for the event, and autonomic arousal; sleepwalking can include wandering or repetitive actions. Sleep terrors are abrupt episodes of fear, screaming, and autonomic signs. REM sleep behavior disorder features dream-enactment behaviors due to loss of normal atonia; nightmares are distressing dreams typically arising during REM sleep with partial awakening. Sleep paralysis is a transient inability to move upon waking or falling asleep. Sleep-related eating disorder involves episodes of eating after awakening with little memory, often during partial arousals. Sexsomnia includes sexual activities during sleep with minimal awareness.

Causes and risk factors: Sleep deprivation, irregular schedules, stress, alcohol or sedatives, and medications can precipitate parasomnias. Underlying neurological or psychiatric disorders can contribute, and REM sleep behavior disorder is more common in older adults and can precede neurodegenerative disease. A family history increases risk for several parasomnias.

Diagnosis and management: Evaluation relies on history, sleep diaries, and sometimes overnight polysomnography with video. Management emphasizes safety measures (remove hazards, secure objects, padded surfaces), adequate sleep, and addressing underlying conditions. Treatments vary by disorder: improving sleep hygiene; melatonin or clonazepam for REM sleep behavior disorder; cognitive-behavioral therapy for nightmares; and individualized pharmacologic therapy as needed. Most parasomnias resolve with age or with improved sleep in children; adults may improve with sleep stabilization.