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ICD-10 F51.3
ICD-9 307.4
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Sleepwalking (also called somnambulism or noctambulism[1]) is a parasomnia or sleep disorder where the sufferer engages in activities that are normally associated with wakefulness while he or she is asleep or in a sleep-like state. Sleepwalking is usually defined by or involves the person affected apparently shifting from his or her prior sleeping position and moving around and performing normal actions as if awake (cleaning, walking and other activities). It is inexact to assume that somnambulists are unconscious during their nocturnal sleepwalking episodes. They are simply not conscious of their actions on a level where memory of the sleepwalking episode can be recalled[How to reference and link to summary or text], and because of this, unless the sleepwalker is awakened or aroused by someone else, this sleep disorder can go unnoticed. Sleepwalking is more commonly experienced in people with high levels of stress, anxiety or psychological factors and in people with genetic factors (family history), or sometimes a combination of both.

A common misconception is that sleepwalking is acting out the physical movements within a dream, but in fact, sleepwalking occurs earlier on in the night when rapid eye movement (REM), or the "dream stage" of sleep, has not yet occurred.[How to reference and link to summary or text]


Sleepwalking can affect people of any age. It generally occurs when an individual moves during slow wave sleep or SWS (during stage 3 or 4 of slow wave sleep—deep sleep) (Horne, 1992; Kales & Kales, 1975). In children and young adults, up to 80% of the night is spent in SWS (50% in infants).[How to reference and link to summary or text] However, this decreases as the person ages, until none can be measured in the geriatric individual.[How to reference and link to summary or text] For this reason, children and young adults (or anyone else with a high amount of slow wave sleep [SWS]) are more likely to be woken up and, for the same reasons, they are witnessed to have many more episodes than the older individuals.[How to reference and link to summary or text]


Activities such as eating, bathing, urinating, talking, dressing, driving cars, painting, whistling, dancing, committing murder, or [2][3][4] engaging in sexual intercourse[5] have been reported or claimed to have occurred during sleepwalking. In December 2008, reports were published of a woman who sent semi-coherent emails while sleepwalking, including one inviting a friend round for dinner and drinks.[6]

Contrary to popular belief, most cases of sleepwalking do not consist of walking around (without the conscious knowledge of the subject). Most cases of somnambulism occur when the person is awakened (something or someone disturbs their SWS); the person may sit up, look around and immediately go back to sleep. But these kinds of incidences are rarely noticed or reported unless recorded in a sleep clinic.[How to reference and link to summary or text]

Sleepwalkers engage in their activities with their eyes open so they can navigate their surroundings, not with their eyes closed and their arms outstretched, as often parodied in cartoons and films. The subject's eyes may have a glazed or empty appearance, and if questioned, the subject will be slow to answer and may be unable to respond in an intelligible manner.[dubious]

Hazards and safety

When sleepwalkers are a danger to themselves or others (for example, when climbing up or down steps or trying to use a potentially dangerous tool such as a stove or a knife), steering them away from the danger and back to bed is advisable. It has even been reported that people have died or were injured as a result of sleepwalking.[7].[8] Sleepwalking should not be confused with psychosis.

Sleepwalking has in rare cases been used as a defense (sometimes successfully) against charges of murder (see Homicidal somnambulism).


In some rare cases, a person may enter into the behaviors consistent with sleepwalking from a state of being awake and alert. This disorder is usually diagnosed as a form of epilepsy known as automatism. An attack usually begins with little or no warning. The subject may engage in simple gestures or small movements, or less commonly, complex behaviors like cooking or driving, performing the activity as if fully alert. After the seizure ends, the subject has no memory of the event, and often feels disoriented[9].

Legal defense

Main article: Homicidal somnambulism

Sleepwalking has from time to time been proposed as a defense against criminal charges — sometimes successfully, sometimes not.

  • In Massachusetts, United States in 1846, Albert Tirrell was found not guilty of murder and arson, arguing that if he did do it, he was sleepwalking at the time. This was the first successful acquittal using a sleepwalking defense in American legal history.[10]
  • In Ontario, Canada, Kenneth Parks was acquitted of all charges in 1987 killing of his in-laws, after evidence presented at his trial pointed to sleepwalking as the only possible explanation for his actions. He did not serve time in a mental ward because "noninsane automatism" (i.e., sleepwalking) was not legally viewed as a mental disorder in Canada.[11]
  • In Arizona, United States in 1999, Scott Falater was convicted of murdering his wife. His sleepwalking defense was countered by prosecution arguments that his actions during the killing had been too complex to have been carried out while sleepwalking.[12]

Main article: Sleepwalking: History of the disorder.
Main article: Sleepwalking:Theoretical approaches.
Main article: Sleepwalking:Epidemiology.
Main article: Sleepwalking:Risk factors.
Main article: Sleepwalking:Etiology.
Main article: Sleepwalking:Diagnosis & evaluation.
Main article: Sleepwalking:Comorbidity.
Main article: Sleepwalking:Treatment.
Main article: Sleepwalking:Prognosis.
Main article: Sleepwalking:Service user page.
Main article: Sleepwalking:Carer page.

See also


  1. That is, somn-ambulism, sleep-walking, walking in one's sleep, or noct-ambulism, night-walking, walking in the night.
  2. Sleepwalk to Murder
  3. Sleepwalking, sleep murder, sleep walking, automatism, sleep apnea, insanity defense, obstructive sleep apnea, narcolepsy, insomnia, cataplexy, sleepiness, sleep walking, daytime sleepiness, upper airway, CPAP, hypoxemia, UVVP, uvula, Somnoplasty, ob...
  4. CNN - Sleepwalking defense in Arizona murder trial - May 25, 1999
  5. includeonly>Rachel Nowak. "Sleepwalking woman had sex with strangers", New Scientist, 2004-10-15. Retrieved on 2007-04-30.
  6. Telegraph, December 17 2008.
  7.,1518,502518,00.html?Punchline=Tada German Sleepwalker Steps Out of 4th-Floor Window
  8. includeonly>Houlihan, Liam, Hudson, Fiona. "Star's sleepwalk death", Sunday Mail, 2008-01-06. Retrieved on 2008-01-06.
  10. Kappman (ed), Edward W. (1994). Great American Trials, 101–104, Detroit, MI: Visible Ink Press.
  11. Man Acquitted Of Sleepwalking Murder Running For School Trustee In Durham
  12. Martin, Lawrence. Can sleepwalking be a murder defense? 26 Apr. 2008. <>.


Key Texts – Books

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Key Texts – Papers

Additional material - Papers

External links

Instructions_for_archiving_academic_and_professional_materials Sleepwalking: Academic support materials

  • Sleepwalking: Academic: Lecture slides
  • Sleepwalking: Academic: Lecture notes
  • Sleepwalking: Academic: Lecture handouts
  • Sleepwalking: Academic: Multimedia materials
  • Sleepwalking: Academic: Other academic support materials
  • Sleepwalking: Academic: Anonymous fictional case studies for training
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