Sleepwalking

Sleepwalking is a non-rapid eye movement sleep disorder characterized by repeated episodes of complex motor behavior initiated during sleep, including rising from bed and walking about. Sleep walking episodes begin during any stage of NREM sleep, most commonly during slow-wave sleep and therefore most often occurring during the first third of the night.

During episodes, the individual has reduced alertness and responsiveness, a blank stare, and relative unresponsiveness to communication with others or efforts by others to awaken the individual. If awakened during the episode (or on awakening the following morning), the individual has limited recall for the episode. After the episode, there may initially be a brief period of confusion or difficulty orienting, followed by full recovery of cognitive function and appropriate behaviour.

Prevalence

10% to 30% of children have had at least one episode of sleepwalking, and 2%-3% sleepwalk often. The prevalence of sleepwalking disorder, marked by repeated episodes and impairment or distress, is much lower, probably in the range of 1%-5%. The prevalence of sleepwalking episodes (not sleepwalking disorder) is 1-7% among adults, with weekly to monthly episodes occurring in about 0.5%. The lifetime prevalence of sleepwalking in adults is 29%, with a past-year prevalence of sleepwalking of 3%.

Criterion A

Recurrent episodes of incomplete awakening from sleep, usually occurring during the first third of the major sleep episode, accompanied by the following:

  1. Sleepwalking: Repeated episodes of rising from bed during sleep and walking about. While sleepwalking, the individual has a blank, staring face; is relatively un responsive to the efforts of others to communicate with him or her; and can be awakened only with great difficulty.
Criterion B

No or little (e.g., only a single visual scene) dream imagery is recalled.

Criterion C

Amnesia for the episodes is present.

Criterion D

The episodes cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

Criterion E

The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication).

Criterion F

Co-existing mental and medical disorders do not explain the episodes of sleepwalking.

Sleepwalking episodes can include a wide variety of behaviours. Episodes may begin with confusion: the individual may simply sit up in bed, look about, or pick at the blanket or sheet. This behaviour then becomes progressively complex. The individual may actually leave the bed and walk into closets, out of the room, and even out of buildings. Individuals may use the bathroom, eat, talk, or engage in more complex behaviours. Running and frantic attempts to escape some apparent threat can also occur. Most behaviours during sleep walking episodes are routine and of low complexity. However, cases of unlocking doors and even operating machinery (driving an automobile) have been reported. Sleepwalking can also include inappropriate behaviour (e.g., commonly, urinating in a closet or waste basket). Most episodes last for several minutes to a half hour but may be more protracted. Inasmuch as sleep is a state of relative analgesia, painful injuries sustained during sleep walking may not be appreciated until awakening after the fact.

There are two “specialized” forms of sleepwalking: sleep-related eating behaviour and sleep-related sexual behaviour (sexsomnia or sleep sex). Individuals with sleep-related eating experience unwanted recurrent episodes of eating with varying degrees of amnesia, ranging from no awareness to full awareness without the ability to not eat. During these episodes, inappropriate foods may be ingested. Individuals with sleep-related eating disorder may find evidence of their eating only the next morning. In sexsomnia, varying degrees of sexual activity (e.g., masturbation, fondling, groping, sexual intercourse) occur as complex behaviours arising from sleep without conscious awareness. This condition is more common in males and may result in serious interpersonal relationship problems or medico-legal consequences.

NREM sleep arousal disorders occur most commonly in childhood and diminish in frequency with increasing age. The onset of sleepwalking in adults with no prior history of sleepwalking as children should prompt a search for specific etiologies, such as obstructive sleep apnea, nocturnal seizures, or effect of medication.

Sedative use, sleep deprivation, sleep-wake schedule disruptions, fatigue, and physical or emotional stress increase the likelihood of episodes. Fever and sleep deprivation can produce an increased frequency of NREM sleep arousal disorders. A family history for sleepwalking or sleep terrors may occur in up to 80% of individuals who sleepwalk. The risk for sleepwalking is further increased (to as much as 60% of offspring) when both parents have a history of the disorder.

Polysomnography

NREM sleep arousal disorders arise from any stage of NREM sleep but most commonly from deep NREM sleep (slow-wave sleep). They are most likely to appear in the first third of the night and do not commonly occur during daytime naps. During the episode, the polysomnogram may be obscured with movement artifact. In the absence of such artifact, the electroencephalogram typically shows theta or alpha frequency activity during the episode, indicating partial or incomplete arousal.

Polysomnography in conjunction with audiovisual monitoring can be used to document episodes of sleepwalking. In the absence of actually capturing an event during a polysomnographic recording, there are no polysomnographic features that can serve as a marker for sleepwalking. Sleep deprivation may increase the likelihood of capturing an event. As a group, individuals who sleepwalk show instability of deep NREM sleep, but the overlap in findings with individuals who do not sleepwalk is great enough to preclude use of this indicator in establishing a diagnosis.

  • Nightmare disorder
  • Breathing-related sleep disorders
  • REM sleep behaviour disorder
  • Parasomnia overlap syndrome
  • Sleep-related seizures
  • Alcohol-induced blackouts
  • Dissociative amnesia, with dissociative fugue
  • Malingering or other voluntary behaviour occurring during wakefulness
  • Panic disorder
  • Medication-induced complex behaviours
  • Night eating syndrome

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