Disorders of arousal from non-rapid eye movement (NREM) sleep are defined by the incomplete arousal from NREM sleep. Patients demonstrate behaviors usually associated with wakefulness while still asleep. Events such as sleepwalking, sleep terrors, and confusional arousals are common in children and to a lesser extent in adults. Approximately 30% of children have sleepwalking or sleep terror events, and the reported prevalence in adults ranges from 2% to 5%.35–37 The decrease in NREM events with increasing age raises the possibility that these disorders may represent an aberrance of maturation of sleep-wake regulation.
Frequently, patients with a NREM parasomnia disorder have a family history.38 First-degree relatives of a patient with sleepwalking have a tenfold greater incidence of sleepwalking.
Typically, NREM events are more common in the first one-third of the night. Patients are amnestic for the event, although a brief visual or auditory perception may occur.
Sleepwalking events can be very elaborate, including behaviors such as dressing, unlocking locks, cleaning, cooking, and driving. Some patients even describe events involving firearms and other potentially dangerous items.39 Patients can recall various feelings or impressions from the events and, rarely, some imagery.
A potential variant of this behavior is nocturnal eating disorder, in which patients arise during the night and eat high-calorie food. The patients generally have different eating habits than their usual daytime habits and have no memory for the events. Patients may eat raw meats, candies with the wrappers, or boxes of cookies. Patients may describe awakening in the morning to find a messy kitchen and food particles still on their bedclothes and in their hair. Occasionally, these events coincide with periods of restricted caloric intake.38
Sleep terrors are a more intense form of sleepwalking. Most patients with sleep terrors also have sleepwalking events. The predominance of autonomic expression during sleep terrors helps to distinguish these events from other partial arousals from NREM sleep. The sudden arousal from slow-wave sleep with a piercing scream or cry, accompanied by autonomic and behavioral manifestations of intense fear, is rarely forgotten by any witness. The onset of the events is abrupt, and patients have tachycardia, tachypnea, flushing, diaphoresis, and mydriasis. The patients are confused and disoriented, and attempts to intercede may result in harm to the person trying to wake the patient. Patients can become violent, resulting in injury to themselves and bed partners.
About 3% of children and fewer than 1% of adults may have these events.36,37
Confusional arousals can occur at any arousal from NREM sleep. They are characterized by disorientation, slow speech and mentation, or inappropriate behavior.40 The patients have memory impairment for the event, and the events can be induced with forced arousal. The course of these events usually improves with age and remains stable in adults.
The diagnosis of NREM arousal disorder is usually made by history. If any atypical characteristics are present, video-EEG polysomnography should be performed to exclude seizure activity. Atypical characteristics include:
Reviewed and revised April 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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