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Parasomnias are disorders characterized by abnormal behavioral or physiological events occurring in association with sleep, specific sleep stages, or sleep-wake transitions. Unlike dyssomnias, parasomnias do not involve abnormalities of the mechanisms generating sleep-wake states, nor of the timing of sleep and wakefulness. Rather, parasomnias represent the activation of physiological systems at inappropriate times during the sleep-wake cycle. In particular, these disorders involve activation of the autonomic nervous system, motor system, or cognitive processes during sleep or sleep-wake transitions. Different parasomnias occur at different times during sleep, and specific parasomnias often occur during specific sleep stages. Individuals with parasomnias usually present with complaints of unusual behavior during sleep rather than complaints of insomnia or excessive daytime sleepiness.

The parasomnias are characterized by undesirable physical events that disrupt sleep. Parasomnias are subdivided in the ICSD-DCM into disorders of arousal, sleep-wake transition disorders, REM parasomnias, and miscellaneous parasomnias (Table 17-3) (Thorpy 1990). Most of the symptoms are manifestations of central nervous system activation, specifically motor and autonomic discharge. All parasomnias are more common in males than in females, and persons with one type of parasomnia are more likely to manifest symptoms of another. Children with sleep terrors usually sleepwalk when they reach an older age. Positive family histories of parasomnias are common.

This section includes Nightmare Disorder, Sleep Terror Disorder, Sleepwalking Disorder, and Parasomnia Not Otherwise Specified.

• 307.47 Nightmare Disorder (formerly Dream Anxiety Disorder)
• 307.46 Sleep Terror Disorder
• 307.46 Sleepwalking Disorder
• 307.47 Parasomnia Not Otherwise Specified

These disorders are fairly common in children and less so in adults.

Classification & Clinical Findings

A. Sleep Terror
Sleep terror (pavor nocturnus) is an abrupt, terrifying arousal from sleep, usually in preadolescent boys although it may occur in adults as well. It is distinct from sleep panic attacks. Symptoms are fear, sweating, tachycardia, and confusion for several minutes, with amnesia for the event.

B. Nightmares

Nightmares occur during REM sleep; sleep terrors in stage 3 or stage 4 sleep.

C. Sleepwalking