When Sleepwalking Becomes Dangerous

There is now good evidence that parts of the brain may be awake while other parts are asleep. Sleepwalking is a premiere example: The portion of the brain capable of generating complex behaviors is awake while those portions which normally monitor our activity and lay down memory of our behaviors are asleep.
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By Mark W. Mahowald, M.D.

A 15-year-old boy was referred to Stanford's sleep clinic for evaluation of severe injuries sustained during a sleepwalking episode. On the night of the injurious event, he had participated in an evening track meet and did not arrive home until midnight. Approximately two hours after falling asleep, he had a sleepwalking episode during which he left the bed, unlocked the bedroom window, and fell out of the first story window. He struck his face on the concrete sidewalk below, resulting in the loss of four teeth, severe damage to his braces, and a fractured lower jaw.

Prior to this event, there was a history of occasional non-violent and non-injurious sleepwalking episodes occurring every 2-3 months. These events were typically characterized by his walking around in the house, attempting to leave the house, or trying to take a shower. His parents were usually successful in redirecting him back to his bed.

He was the product of a normal pregnancy and delivery. There was no history of neurologic or psychiatric disease. He was performing well in school and was a regular participant in after-school athletics. There was no history of recreational drug or alcohol use, and he was taking no prescription medications. His father had a history of occasional benign sleepwalking that resolved spontaneously in his teenage years.

A formal sleep study was normal. Recommendations for treatment included suggestions on environmental safety and the consideration of medications.

So-called "disorders of arousal" are the most common cause of complex behaviors arising from the sleep period. These disorders occur on a broad spectrum including confusional arousals, sleepwalking, and sleep terrors. Some take the form of specialized behaviors such as sleep-related eating (as discussed previously) and sleep-related sexual activity without conscious awareness. It was formerly erroneously thought that these disorders may be related to underlying psychiatric or psychological problems, particularly if they began in or persisted into adulthood. This is not the case.

The concepts that sleep is a global, whole-brain phenomenon and that wakefulness and sleep are mutually exclusive are erroneous. There is now good evidence that parts of the brain may be awake while other parts are asleep. Sleepwalking is a premiere example: The portion of the brain capable of generating complex behaviors is awake while those portions which normally monitor our activity and lay down memory of our behaviors are asleep. This leaves the brain capable of producing complex behaviors without conscious awareness or memory of that behavior.

These disorders arise from all stages of non-rapid eye movement (NREM) sleep. Unlike arousals from nightmares (which tend to occur during REM sleep), there is little recall of dream-like imagery. That these arousals are not necessarily the culmination of ongoing psychologically significant mentation is evidenced by the fact that sleepwalking can be induced in normal children by standing them up during deep NREM sleep and that sleep terrors can be precipitously triggered in susceptible individuals by sounding a buzzer during deep NREM sleep.

Let us consider some of the characteristics of each condition:

  • Confusional Arousals -- These are often seen in children and are characterized by movements in bed, occasionally thrashing about, or inconsolable crying.

  • Sleepwalking -- Most prevalent in childhood (1-17 percent) and peaking at 11-12 years of age, sleepwalking is more common in adults (3-4 percent) than generally acknowledged. Sleepwalking may be either calm or agitated, with varying degrees of complexity and duration.
  • Sleep Terror -- This is the most dramatic disorder of arousal. It is frequently initiated by a loud, blood-curdling scream associated with extreme panic, followed by prominent motor activity such as hitting the wall, running around or out of the bedroom (even out of the house), resulting in bodily injury or property damage. They are often associated with a sense of dread or impending doom and an overwhelming urge to escape -- hence the common consequence of running toward an open door or window. A universal feature is inconsolability. Although the victim appears to be awake, he or she usually misperceives the environment, and attempts at consolation are fruitless and may serve only to prolong and intensify the confusional state. Complete amnesia for the activity is typical, but may be incomplete.
  • These various disorders of arousal may be triggered by febrile illness, and, as in the above case example, sleep deprivation. A family history is often present.

    Formal sleep studies may be indicated to eliminate the possibility of other sleep disorders such as obstructive sleep apnea or nocturnal seizures masquerading as disorders of arousal. The sleep studies in the disorders of arousal are usually unremarkable. Given the high prevalence of these disorders in the general population, formal sleep disorder center evaluation should be confined to those cases in which the behaviors: 1) are potentially injurious or violent, 2) are extremely bothersome to other household members, 3) result in symptoms of excessive daytime sleepiness, or 4) have unusual characteristics.

    Treatment is often not necessary. Reassurance of their typically benign nature, lack of psychological significance, and the tendency to diminish over time is often sufficient. If the behaviors are potentially injurious or violent, it is mandatory to make the sleep environment safe (sleeping on the first floor, hanging heavy curtains over windows, installing infrared alarms in the bedroom doorway, etc.). Although there are no rigorous studies documenting the effectiveness of any specific medication, tricyclic antidepressants such as imipramine and benzodiazepines such as clonazepam are thought to be effective. Hypnosis may also be effective. The avoidance of sleep deprivation is also important.

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    1. Mahowald MW, Cramer Bornemann MA. "Non-REM arousal parasomnias." In: Kryger MH, Roth T, Dement WC, editors. Principles and Practice of Sleep Medicine. 5th ed. St. Louis, MO: Saunders/Elsevier; 2011. p. 1075-82.

    2. Ohayan MM, Mahowald MW, Dauvilliers Y, Krystal AD, Leger D. "Prevalence and comorbidity of nocturnal wanderings in the U.S. adult general population." Neurology. 2012.

    Mark W. Mahowald, MD., is a visiting professor at Stanford Center for Sleep Sciences and Medicine. This Center is the birthplace of sleep medicine and includes research, clinical, and educational programs that have advanced the field and improved patient care for decades. To learn more, visit us at: