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Sleep Sex (Definitions and prevalence of sleep sex or sexsomnia)

What is sleep sex?

Sleep sex, also called sexsomnia, refers to a sleep disorder where sexual behaviors are initiated and occur while an individual is asleep either involving a partner or in the presence of a partner. Sleep sex is in fact one type of sleep disorder (parasomnia) that involves sexual behaviors. Only recently have researchers documented enough cases of sleep sex to propose that it be considered a unique diagnosis of sleep disorder.

Sleep sex encompasses a range of sexual behaviors, including (but probably not limited to):

  • sexual touching of another person
  • sexual vocalizations (moaning) and talking
  • masturbation (with and without orgasm)
  • performing oral sex
  • sexual intercourse (with and without orgasm)

While there are too few documented cases for researchers to describe sleep sex conclusively, the current understanding is that in cases of genuine sexsomnia, the behaviors are “involuntary” in that the sleeping person initiating them is unaware they are happening, and often has no memory of them occurring when confronted at a later point with the behavior.

In several case studies, partners who are sexually acted upon describe having to shake or slap their partner to wake them up, at which point they appear disoriented and confused.

Interestingly, in some cases, the partner reports that the sexual behavior during sleep is significantly different from the sexual behavior while awake (and in two cases I read, the sleep sex was preferred).

How common is sleep sex?

There isn’t enough research to establish how common sleep sex is. Researchers who have studied multiple cases of sleep sex suggest that it is likely more common than we know, as they have routinely found people reticent to talk about their sleep sex behaviors until directly asked about it. Since most physicians do not ask about sleep sex, we probably have no sense of the prevalence in the general population.

A 2010 review of the charts of 832 sleep clinic patients found that 7.6% responded yes when asked if they had ever initiated sexual activity with a partner while asleep, but the majority of patients never discussed this with a doctor unless they were asked about it.

Sleep sex seems to be more common among men, although there are reported cases of women initiating sexual behaviors while sleeping. In a review of 32 cases of sleep disorders with sexual behavior, 80% of the cases involved men and 20% women. In the more recent review of 832 patients, 11% of those reporting sleep sex symptoms were men, while 4% were women.

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What causes sleep sex?

The causes of sleep sex, and even what physiological and neurological mechanisms underlie sleep sex, are still being explored. Many people who are found to engage in sleep sex have other sleep disorders. Some of them also have substance abuse issues and other psychological issues. It seems likely that there is not one kind of sleep sex, and not one single cause for the condition.

What is the connection between sleep sex and sexual assault?

Some of the earliest cases of sleep sex came to the attention of clinicians in the context of court cases where an individual was arrested for sexual assault and claimed to have been asleep and have no memory of committing a sexual assault.

Several of the case studies of sleep sex include information about charges being laid, and once evidence of sleep disturbances are presented in court the accused individual has been acquitted (although this is not always the case). In cases where evidence of sleep disorder is presented, it is usually diagnosed by detailed observations during sleep.

In some ways, it’s troubling that a disorder that is so newly described could be used (possibly illegitimately) by people who commit sexual assaults. Yet there seems to be agreement on the part of sleep researchers that sleep sex represents a real disorder that involves essentially involuntary sexual initiation. A large review of sleep sex cases and research included a recommendation that individuals diagnosed with this disorder who have been arrested and acquitted on sexual assault charges resulting from sleep sex be informed that they cannot in the future use sleep sex as a defense. Hopefully, more research will provide ways of further diagnosing people with sleep sex disorders, and ensure that the disorder is not used as an alibi, and people with the disorder are given proper access to treatment and prevention methods.


  • Ebrahim, I.O. “Somnambulistic Sexual Behaviour (Sexsomnia).” Journal of Clinical Forensic Medicine Volume 13, No. 4 (2006): 219-224.
  • Schenk, C.H., Arnulf, I., & Mahowald, M.W. “Sleep and Sex: What Can Go Wrong? A Review of the Literature on Sleep-Related Disorders and Abnormal Sexual Behaviors and Experiences.” Sleep Volume 30, No. 6 (2007): 683-702.
  • Shapiro, C.M., Trajanovic, N.N., & Fedoroff, J.P. “Sexsomnia – A new parasomnia?” Canadian Journal of Psychiatry Volume 48, No. 5 (2003): 311-317
Amie Dawson, Ph.D.

Amie Dawson, Ph.D.

Amie is your go-to gal for all things related to sex and sexual well-being.

A certified sex educator and award-winning sex toy reviewer, Amie has spent her career empowering individuals and couples to embrace their sexuality.

With a Ph.D. in Human Sexuality and an ever-growing collection of over 200 vibrators, she's got the knowledge and experience to guide you on your pleasure-seeking journey.

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