Parasomnias are abnormal behaviors, perceptions, dreams, or autonomic activity during specific sleep stages or sleep-wake transitions. They divide into two major categories: NREM parasomnias (arising from NREM 3 — slow-wave sleep) and REM parasomnias (the most clinically important being RBD, covered separately).
NREM arousal disorders arise from incomplete arousal out of NREM 3 sleep — the patient is partially awake (behaviorally) but partially asleep (cognitively). Typically presents in childhood; most remit with maturation; some persist or recur in adults.
Sleepwalking (somnambulism) — walking or performing complex behaviors during sleep with eyes open, no recall in morning. Often gentle activities (going to bathroom, walking around bedroom) but can include unlocking doors, leaving the house, driving (rare). Safety concerns substantial in adults.
Sleep terrors (night terrors) — sudden arousal with screaming, intense fear, autonomic activation (tachycardia, sweating, dilated pupils). Patient often cannot be consoled during episode. No recall in morning. Distinct from nightmares (which arise from REM with recall). Typically pediatric; can be very distressing for parents to witness.
Confusional arousals — incomplete arousal with confusion, disorientation, sometimes complex behaviors. No recall in morning. Often during attempted awakening from NREM 3.
Sleep-related eating disorder — episodes of eating during apparent sleep, often with no recall. Sometimes consuming unusual items. Can be associated with zolpidem use.
Sexsomnia — sexual behaviors during sleep. Legal and relational implications when present.
Adult-onset NREM parasomnias should prompt evaluation for underlying triggers:
Sleep apnea — particularly common precipitant; fragmented NREM 3 sleep predisposes. Treatment of OSA often resolves parasomnia.
Medications — zolpidem and other z-drugs have produced complex sleep behaviors with no recall; some antipsychotics; some antidepressants.
Alcohol — sleep architecture disruption.
Sleep deprivation — promotes NREM 3 rebound that increases parasomnia.
Stress and anxiety — well-documented precipitants.
Fever (in children) — common trigger.
Diagnosis: primarily clinical history. Polysomnography may help: rule out OSA, identify epileptiform activity (nocturnal seizures can mimic parasomnias), confirm pattern.
Differential — nocturnal frontal lobe epilepsy — can closely mimic parasomnias. Features suggesting seizure: stereotyped semiology episode-to-episode, occurrence from any sleep stage, brief duration (seconds-minutes), sometimes daytime auras, postictal symptoms. EEG with video monitoring confirms.
Management:
Safety — locks on bedroom doors, alarms for sleepwalkers, padded bed for severe sleep terrors, partner sleeping separately if dangerous, no firearms or sharp objects accessible.
Address triggers — treat sleep apnea, eliminate offending medications, improve sleep schedule, address stress.
Pharmacotherapy for severe persistent cases: low-dose clonazepam at bedtime. Reserve for cases with safety concerns or significant impairment.
Reassurance for children — most parasomnias remit with maturation. Reassure parents of benign nature in most cases.
When you encounter a patient (often a child) with parasomnias, history and safety planning are the first step. Adult-onset cases warrant trigger evaluation. Most childhood parasomnias remit; persistent or dangerous cases respond to targeted treatment.