Diagnostic Features

The essential feature of Sleepwalking Disorder is repeated episodes of complex motor behavior initiated during sleep, including rising from bed and walking about. Sleepwalking episodes begin during slow-wave sleep and therefore most often occur during the first third of the night (Criterion A). During episodes, the individual has reduced alertness and responsiveness, a blank stare, and relative unresponsiveness to communication with others or efforts to be awakened by others (Criterion B). If awakened during the episode (or on awakening the following morning), the individual has limited recall for the events of the episode (Criterion C). After the episode, there may initially be a brief period of confusion or difficulty orienting, followed by full recovery of cognitive function and appropriate behavior (Criterion D). The sleepwalking must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning (Criterion E). Sleepwalking Disorder should not be diagnosed if the behavior is due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition (Criterion F).

Sleepwalking episodes can include a variety of behaviors. In mild episodes (sometimes called “confusional arousals”), the individual may simply sit up in bed, look about, or pick at the blanket or sheet. More typically, the individual actually gets out of bed and may walk into closets, out of the room, up and down stairs, and even out of buildings. Individuals may use the bathroom, eat, and talk during episodes. Running and frantic attempts to escape some apparent threat can also occur. Most behaviors during sleepwalking episodes are routine and of low complexity. However, cases of unlocking doors and even operating machinery have been reported. Particularly in childhood, sleepwalking can also include inappropriate behavior (e.g., urinating in a closet). Most episodes last for several minutes to a half hour.

Sleepwalking episodes can terminate in spontaneous arousals followed by a brief period of confusion, or the individual may return to bed and continue to sleep until the morning. Not uncommonly, the individual may awaken the next morning in another place, or with evidence of having performed some activity during the night, but with complete amnesia for the event. Some episodes may be followed by vague recall of fragmentary dream images, but usually not by typical storylike dreams.

During sleepwalking episodes, individuals may talk or even respond to others’ questions. However, their articulation is poor, and true dialogue is rare. Individuals may respond to others’ requests to cease their activity and return to bed. However, these behaviors are performed with reduced levels of alertness, and awakening an individual from a sleepwalking episode is typically very difficult. If awakened, the individual remains confused for several minutes and then returns to a normal state of alertness.

For the diagnosis to be made, the individual must experience clinically significant distress or impairment. Individuals may avoid situations that would reveal their behavior to others (e.g., children may avoid visiting friends or going to summer camp; adults may avoid sleeping with bedpartners, going on vacation, or staying away from home). Social isolation or occupational difficulties can result.

Associated Features and Disorders

Associated descriptive features and mental disorders. Internal stimuli (e.g., a distended bladder) or external stimuli (e.g., noises) can increase the likelihood of a sleepwalking episode, as can psychosocial stressors and alcohol or sedative use. Some individuals with sleepwalking also report episodes of eating during the night, most often with complete or partial amnesia. They may find evidence of their eating only the next morning. Individuals can injure themselves during sleepwalking episodes by bumping into objects, walking on stairs, going outside, and even walking out of windows. The risk of injury further increases if sleepwalking episodes also include features of sleep terrors, with an attendant fleeing or striking out. Individuals with Sleepwalking Disorder and Sleep Terror Disorder can also injure others during episodes.

Other parasomnias associated with non-rapid eye movement (NREM) sleep (e.g., Sleep Terror Disorder) can also occur in individuals with Sleepwalking Disorder. Sleepwalking Disorder in children usually is not associated with other mental disorders, but in adults it may be associated with Personality Disorders, Mood Disorders, or Anxiety Disorders.

Associated laboratory findings. Polysomnography, using routine procedures with the addition of audiovisual monitoring, can document episodes of sleepwalking. The majority of sleepwalking episodes begin within the first few hours of sleep, typically during NREM stage 3 or 4 sleep, although some individuals (e.g., older adults) may have episodes during NREM stage 2 sleep. Preceding the episode, the EEG often shows rhythmic (“hypersynchronous”), high-voltage delta activity that persists during the arousal. EEG signs of arousal, such as alpha activity, may also appear at the beginning of the episode. Most commonly, the EEG is obscured by movement artifact during the actual episode. Heart rate and respiratory rate may increase at the beginning of the episode. These findings may occur with a full sleepwalking episode or with a more minor behavioral event (such as a confusional arousal). Other polysomnographic findings may include an increased number of transitions out of stages 3 and 4 sleep and reduced sleep efficiency. Other polysomnographic findings may include an increased number of transitions out of stages 3 and 4 sleep, increased awakenings during NREM sleep, and reduced sleep efficiency. Sleep-stage architecture may show an increase in NREM stages 3 and 4 sleep but is otherwise unremarkable. Sleep apnea and periodic limb movements are seen in a minority of individuals with Sleepwalking Disorder.

Associated physical examination findings and general medical conditions. Fever or sleep deprivation can increase the frequency of sleepwalking episodes. Obstructive sleep apnea syndrome, periodic limb movement disorder, and other disorders that produce severe disruption of slow-wave sleep can also be associated with sleepwalking episodes. An association has been noted between Sleepwalking Disorder and migraine headaches, Narcolepsy, and other neurological conditions in a subset of individuals.

Specific Culture, Age, and Gender Features

No reports have provided clear evidence of culturally related differences in the manifestations of Sleepwalking Disorder, but it is likely that the significance and causes attributed to sleepwalking differ among cultures. In clinical samples, violent activity during sleepwalking episodes is more likely to occur in adults (particularly in men), whereas eating during sleepwalking episodes is more commonly seen in women. Sleepwalking Disorder occurs more often in females during childhood but more often in males during adulthood.

Prevalence

Between 10% and 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%. Epidemiological surveys report the prevalence of sleepwalking episodes (not Sleepwalking Disorder) to be 1.0%-7.0% among adults, with weekly to monthly episodes occurring in 0.5%-0.7%.

Course

Sleepwalking can occur at any time after a child is able to walk, but episodes most commonly occur for the first time between ages 4 and 8 years. The peak prevalence occurs at about age 12. Episodes rarely occur for the first time in adults, although some associated behaviors such as nocturnal eating may begin several years after the sleepwalking itself. The onset of Sleepwalking Disorder in adults with no history of sleepwalking as children should prompt a search for specific etiologies such as substance use or a neurological condition. The majority of adults with Sleepwalking Disorder have a history of episodes during childhood as well. Sleepwalking in childhood usually disappears spontaneously during early adolescence, typically by age 15 years. Less commonly, episodes may have a recurrent course, with return of episodes in early adulthood after cessation of episodes in late childhood. Sleepwalking Disorder in adults most often follows a chronic, waxing and waning course. Sleepwalking episodes may occur as isolated events in individuals of any age, but the most common pattern is repeated episodes occurring over a period of several years.

Familial Pattern

Sleepwalking Disorder aggregates among family members. A family history for sleepwalking or sleep terrors has been reported 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. Genetic transmission is suggested by an increased prevalence of monozygotic, as opposed to dizygotic, twins, but the exact mode of inheritance is not known.

Differential Diagnosis

Many children have isolated or infrequent episodes of sleepwalking, either with or without precipitating events. The exact boundary between nonclinically significant sleepwalking episodes and Sleepwalking Disorder is indistinct. Frequent episodes, injuries, more active or violent behavior, and social impairment resulting from sleepwalking are likely to lead the child’s parents to seek help and warrant a diagnosis of Sleepwalking Disorder. Episodes that have persisted from childhood to late adolescence, or that occur de novo in adults, are more likely to warrant a diagnosis of Sleepwalking Disorder.

It can be difficult clinically to distinguish Sleepwalking Disorder from Sleep Terror Disorder when there is an attempt to “escape” from the terrifying stimulus. In both cases, the individual shows movement, difficulty awakening, and amnesia for the event. An initial scream, signs of intense fear and panic, and autonomic arousal are more characteristic of Sleep Terror Disorder. Sleepwalking Disorder and Sleep Terror Disorder may occur in the same individual, and in such cases both should be diagnosed.

Breathing-Related Sleep Disorder, especially the obstructive sleep apnea syndrome, can also produce confusional arousals with subsequent amnesia. However, Breathing-Related Sleep Disorder is also characterized by characteristic symptoms of snoring, breathing pauses, and daytime sleepiness. In some individuals, Breathing-Related Sleep Disorder may precipitate episodes of sleepwalking.

“REM sleep behavior disorder” is another Parasomnia (see Parasomnia Not Otherwise Specified) that may be difficult to distinguish from Sleepwalking Disorder. REM sleep behavior disorder is characterized by episodes of prominent, complex movements, often involving personal injury. In contrast to Sleepwalking Disorder, REM sleep behavior disorder occurs during rapid eye movement (REM) sleep, often in the later part of the night. Individuals with REM sleep behavior disorder awaken easily and report more detailed and vivid dream content than do individuals with Sleepwalking Disorder. A small number of individuals may have confusional arousals with motor activity that occur during both NREM and REM sleep. The definitive diagnosis in such cases should be based on a careful evaluation of clinical, polysomnographic, and other laboratory findings.

A variety of other behaviors can occur with partial arousals from sleep. Confusional arousals resemble sleepwalking episodes in all respects except the actual movement out of the bed. “Sleep drunkenness” is a state in which the individual shows a prolonged transition from sleep to wakefulness in the morning. It may be difficult to arouse the individual, who may violently resist efforts to awaken him or her. Again, ambulation or other more complex behaviors distinguish Sleepwalking Disorder. However, both confusional arousals and sleep drunkenness may occur in individuals with Sleepwalking Disorder.

Sleep-related seizures can produce episodes of unusual behavior that occur only during sleep. The individual is unresponsive and is amnestic for the episode. Typically, sleep-related epilepsy produces more stereotypical, perseverative, low-complexity movements than those in sleepwalking. In most cases, individuals with sleep-related epilepsy also have similar episodes during wakefulness. The EEG shows features of epilepsy, including paroxysmal activity during the episodes and interictal features at other times. However, the presence of sleep-related seizures does not preclude the presence of sleepwalking episodes. Sleep-related epilepsy should be diagnosed as Sleep Disorder Due to General Medical Condition, Parasomnia Type.

Sleepwalking can be induced by use of, or withdrawal from, substances or medications (e.g., alcohol, benzodiazepines, opiates, cocaine, nicotine, antipsychotics, tricyclic antidepressants, chloral hydrate). In such cases, Substance-Induced Sleep Disorder, Parasomnia Type, should be diagnosed.

Dissociative Fugue bears superficial similarities to Sleepwalking Disorder. Fugue is rare in children, typically begins when the individual is awake, lasts hours or days, and is not characterized by disturbances of consciousness. Sleepwalking must also be distinguished from Malingering or other voluntary behavior occurring during wakefulness, although in some cases such distinctions may be difficult. Features that suggest Sleepwalking Disorder include a positive childhood history, low-complexity or stereotyped behavior during sleepwalking episodes, the absence of secondary gain to the individual from his or her nocturnal behavior, and the presence of typical polysomnographic findings such as repeated arousals from NREM sleep. Furthermore, it may be difficult for the individual to convincingly counterfeit the appearance or behavior of sleepwalking under direct observation or in a video recording made in the sleep laboratory.

Relationship to the International Classification of Sleep Disorders

Sleepwalking Disorder is virtually identical to Sleepwalking as described in the International Classification of Sleep Disorders (ICSD). The ICSD includes two other disorders that may have features similar to sleepwalking: Confusional Arousals and Nocturnal Eating (Drinking) Syndrome.

Diagnostic criteria for 307.46 Sleepwalking Disorder

A. Repeated episodes of rising from bed during sleep and walking about, usually occurring during the first third of the major sleep episode.
B. While sleepwalking, the person has a blank, staring face, is relatively unresponsive to the efforts of others to communicate with him or her, and can be awakened only with great difficulty.
C. On awakening (either from the sleepwalking episode or the next morning), the person has amnesia for the episode.
D. Within several minutes after awakening from the sleepwalking episode, there is no impairment of mental activity or behavior (although there may initially be a short period of confusion or disorientation).
E. The sleepwalking causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
F. The disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.