Definition and Diagnosis
Parasomnias are a group of sleep disorders characterized by undesirable physical events or experiences that occur during entry into sleep, within sleep, or during arousal from sleep, including conditions such as sleepwalking, sleep terrors, and REM sleep behavior disorder.
Epidemiology
Non-REM parasomnias such as sleepwalking and sleep terrors are relatively common in childhood and often resolve by adolescence, while REM sleep behavior disorder is more common in older adults, particularly men, and can be an early marker of neurodegenerative disease.
Risk Factors
Risk factors include a family history of parasomnias, sleep deprivation, irregular sleep schedules, fever, certain medications, alcohol use, and, for REM sleep behavior disorder specifically, underlying neurodegenerative conditions such as Parkinson's disease.
Symptoms and Subtypes
Presentations vary by type: sleepwalking and sleep terrors involve partial arousal from deep non-REM sleep with confusion and limited recall, while REM sleep behavior disorder involves acting out vivid, often violent, dreams due to loss of normal muscle atonia during REM sleep.
Diagnosis
Diagnosis is largely based on clinical history, often supplemented by input from a bed partner or family member, with polysomnography used in ambiguous cases or when REM sleep behavior disorder or another specific parasomnia is suspected.
Treatment
Management includes ensuring a safe sleep environment, addressing precipitating factors such as sleep deprivation or irregular schedules, and, for REM sleep behavior disorder, medications such as melatonin or clonazepam alongside evaluation for underlying neurological conditions.
Prognosis
Childhood non-REM parasomnias typically resolve with age and carry a good prognosis; REM sleep behavior disorder tends to be chronic and warrants ongoing monitoring given its association with future neurodegenerative disease in a substantial proportion of cases.
Reference
New Oxford Textbook of Psychiatry (2nd ed.).