As the field of sleep medicine has grown there has been an increase in referrals to experts specializing in sleep disorders, particularly those associated with the potential for sleep-related violence. A paper published in Chest examined the various types of these disorders and described the number and kinds of related cases referred to a sleep medicine center.1

“This information may begin to bridge the gap between the differing medical and legal concepts of automatisms (complex motor behaviors occurring in the absence of conscious awareness and therefore without culpability),” wrote Michael A. Cramer Bornemann, MD, of the Minnesota Regional Sleep Disorders Center, Hennepin County Medical Center in Minneapolis, and colleauges.1 Despite commonly held beliefs to the contrary, the states of sleep and wakefulness can occur simultaneously. This “state dissociation” can lead to a range of conditions such as parasomnias, which are disorders characterized by “abnormal complex behaviors or experiences and autonomic nervous system activity arising during sleep.”

Several of the disorders implicated in sleep-related violence are highlighted below.

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Disorders of arousal. Most sleep-related forensic cases involve disorders of arousal, which range in complexity from “confusional arousals through sleepwalking to sleep terrors.”1 Although stress has been cited as a potential trigger for episodes in individuals with disorders of arousal, the evidence does not currently suggest a psychological or psychiatric etiology. Disorders of arousal affect up to 30% of children and nocturnal wandering has been observed in approximately 29% of adults.1

These disorders result from the “simultaneous occurrence of wakefulness and [non-rapid eye movement] NREM sleep: portions of the brain capable of generating very complex behaviors are awake, while other portions of the brain responsible for monitoring behavior and laying down memory of behaviors are asleep,” Dr Cramer Bornemann and colleauges explained, making it possible for individuals to enact complex behaviors in the absence of conscious awareness.1

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Sexsomnia. Sexomnia is classified as a subtype of NREM arousal disorders and can involve a wide range of sexual behaviors that may be expressed violently. This disorder usually affects young adult males and may occur in the context of a preexisting NREM sleep parasomnia or obstructive sleep apnea (OSA). The victim in these cases is typically a young female child or adolescent who is not related to the perpetrator.

REM sleep behavior disorder (RBD). RBD involves “dream-enacting behaviors during REM sleep with loss of the physiological skeletal muscle atonia of REM sleep [which] are often aggressive and can become violent, resulting in serious and life-threatening injuries to self and bed partner.”1 These cases typically involve men who are middle-age or older. 

Obstructive sleep apnea (OSA) as “pseudo-RBD.”  Sleep-related behaviors occurring in patients with OSA can occasionally mimic RBD, although normal REM sleep atonia is observed on polysomnography. In these cases, treatment with continuous positive airway pressure (CPAP) reduced the aggressive dream-enacting behaviors in addition to OSA symptoms.

Sleep deprivation and cognitive impairment. Sleep deprivation has been linked with cognitive impairment and motor vehicle accidents at rates similar to those associated with alcohol consumption. “Given that sleep deprivation is a well-established preventable cause of human-error related accidents or errors, there are broad forensics implications for not only the individual but for an employer as well,” the investigators stated.1

Dr Cramer Bornemann and colleauges also examined medico-legal requests to a sleep medicine center pertaining to forensic cases potentially involving sleep-related violence, made most often by attorneys seeking to determine whether a sleep-related condition led to a forensic event. Their findings were as follows:

  • Of 351 requests received over a period of 11 years, sexual assault was the top category among the legal complaints involved in these cases (41%). Other common categories were murder, manslaughter, and aggravated assaultbattery.
  • In the majority of cases, the conditions implicated were parasomnias (57%; most commonly sexsomnia), pharmaceutical adverse effects (30%; almost all related to zolpidem), sleep deprivation (5%), and OSA (4%).
  • Ultimately, 31% of cases referred were accepted for further review and rendering of a legal opinion.
  • Substantial gender disparity was evident in these cases: in those believed to involve parasomnias, the perpetrator was male in 90% of cases and the victim was female in 81% of cases. Regarding sexsomnia specifically, all of the perpetrators were male, and 93% of victims were female.

The researchers concluded that the “ongoing collection of clinical and legal data on cases of suspected sleep-related violent behavior will further define the range of such behaviors including their complexity and duration and will serve to reduce the ill-founded skepticism surrounding these fascinating disorders.”

To learn more about sleep-related violence, Medical Bag spoke with Scott G. Williams, MD, FACP, FAPA, FAASM, director for medicine at Fort Belvoir Community Hospital in Virginia, and associate professor of medicine and psychiatry at the Uniformed Services University of the Health Sciences (USUHS) in Bethesda, Maryland.

Disclaimer: The comments specified in this article are those of the author and do not necessarily reflect the official views of the United States Army, the Defense Health Agency, or the Department of Defense.

Medical Bag: Based on the research published by Dr Bornemann and colleauges in Chest,1 it sounds like there has been an increase in referrals for cases involving sleep-related violence as a potential defense in forensic cases. What are your views on why that might be? Do you have any thoughts on why sexsomnia was the most common disorder implicated in these cases?

Dr Williams: As the paper suggests, there is increasing recognition regarding sleep medicine diagnoses. This is a very new field, and I think that the increased incidence of forensic consultation is a reflection of an increase in the broader understanding of sleep medicine in general. 

Also, there have been some high-profile cases covered in the media that have further served to increase awareness about the possibility of parasomnia behavior resulting in violence. There was even a Hollywood movie in 2013 titled Side Effects that documented medication-induced non-rapid eye movement (NREM) parasomnia activity and its possible role in a murder. 

I would have to speculate as to why sexsomnia is one of the most frequently implicated parasomnia diagnoses, but it probably has more to do with the type of alleged crime than any increase in the true incidence of sexsomnia as a disorder. The paper by Dr Cramer Bornemann and colleagues mentioned that the vast majority (68%) of forensic referrals to their practice were not accepted on the basis of merit or due to the presence of alcohol as confounder.1

Medical Bag: How is sleep-related violence assessed and treated?

Dr Williams: The important aspects of the detailed history as part of a comprehensive evaluation for sleep disorders include both patient and bed partner report. Obviously, if there is no history of parasomnia behavior and the only incident of possible sleep-disordered behavior resulted in the alleged crime, the provider should be skeptical of a parasomnia causing the violence. 

Medical Bag: What are other key implications for clinicians?

Dr Williams: The key focus for clinicians is more related to the management of patients with diagnosed parasomnias, rather than the evaluation of patients alleged to have committed a crime. Clinicians should aim to reduce their patients’ chance of harm to themselves and their bed partners. 

Given that primary care clinics provide the majority of care for patients with parasomnias, there needs to be an awareness that violence is a possibility and that there are precautions that can reduce the risk for harm.

Medical Bag: What should be the focus of future research on this topic?

Dr Williams: There should be equal emphasis on improving diagnostic modalities for parasomnias, as well as improving treatments. Polysomnography is not a very sensitive test for parasomnias because the abnormal behavior does not occur every night and is often not present during the video-monitored testing. Occasionally, multiple-night studies are required,  but that is expensive and time consuming — and thus rarely performed. Also, there is a lack of well-designed trials looking at the role of medication to suppress parasomnia activity, in part because of the infrequent nature of the events.


Cramer Bornemann MA, Schenck CH, Mahowald MW. A review of sleep-related violence: the demographics of sleep forensics referrals to a single center [published online November 23, 2018]. Chest. doi:10.1016/j.chest.2018.11.010