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Sexsomnia: a contentious diagnosis

Sexsomnia: a contentious diagnosis

What is sexsomnia?

Sexomnia is a very rare parasomnia (a sleep disorder related to abnormal movements) predominantly affecting men. Sexsomniacs engage in the following sexual activities while they’re asleep1:

  • sexual vocalisations
  • masturbation
  • fondling
  • intercourse/attempted intercourse.

Sexsomnia (a.k.a. ‘sleepsex’) occurs during non-REM sleep and isn’t related to dreaming. Although abnormal sexual behaviour during sleep was first described in 1989, the term ‘sexsomnia’ wasn’t coined until 2003 when 11 patients exhibiting sexual behaviours during sleep were described2.

Sexsomnia can co-occur alongside other sleep disorders such as sleepwalking, sleep apnoea, night terrors and bedwetting. It may be triggered by:

  • stress
  • previous sleep deprivation
  • excessive consumption of alcohol or drugs.

Treatments that improve the quality of sleep may help reduce the incidence of events.

The implications of sleepsex

In 2000 groundbreaking work was published recording stories and experiences of people who had experienced ‘sleepsex’3. In a loving relationship, it may be understood as ‘just one of those things that happens’ — as the account below suggests:

Sleepsex is great. My husband initiates it while we’re sleeping and then we wake up in the middle of making love. Often it’s better when he’s asleep because we are completely relaxed and uninhibited.

However, given the nature of the behaviour, it may be hard for the bed partner to understand the fact that this behaviour is not deliberate:

During his sleepsex episodes, he becomes very aggressive and violent and then claims he does not remember anything… I had to call 911 last night because of a violent assault.

In extreme cases, sexsomnia has led to accusations of sexual assault — including rape — although the condition has been used successfully as a legal defence in such cases (see sleep and the law article).

As with other parasomnias, sexsomniacs do not remember the acts that they perform while they are asleep.

Sexsomnia and the Law

A review4 of 90 cases of sexsomnia in the literature from nine different countries (including the United States and United Kingdom) found that 82% of the offenders were male. In 97-98% of cases those charged presented amnesia as a defence.

In about a third of the incidents reviewed there were also reports of aggression and violence. Ultimately, 14% of the cases resulted in legal proceedings.

Sexsomnia is now formally recognised in the standard diagnostic manual DSM-55 – essentially the bible of psychiatric disorders. However, the variable presentation of such behaviours and the possibility of falsely claiming it as a defence can cause difficulties for a judge and jury6 7 8.

Luedecke: A study in sexsomnia

A number of the early legal cases concerning sexsomnia as a defence occurred in Canada — the most important of which was R v Luedecke9. This case concerned a defendant who had attended a party in Toronto in 2003 during which he consumed a large amount of alcohol and some magic mushrooms. Apparently:

  • he had been awake for 22 hours before he fell asleep at about 4am
  • he woke to find he was in the middle of nonconsensual sex and the woman was screaming
  • the woman said Luedecke looked ‘completely incoherent’
  • Luedecke said he was ‘completely dazed and in shock’

When he learned later that day that police were looking for someone in connection with a sexual assault, Luedecke contacted the police and gave a voluntary statement.

The judge accepted that Luedecke’s conduct was triggered by the external factors outlined by a sleep expert. According to the defence, excessive sleep deprivation, alcohol, genetic predisposition factors and stress all contributed to circumstances beyond their client’s control.

The judge was satisfied that the defence of sane automatism (i.e. the accused was not responsible for his actions because he did not have conscious control of those actions) was admissible and acquitted Luedecke.

The sexsomnia defence: a modern day dilemma

While it may seem feasible for a single act to take place as the result of sexsomnia, it’s perhaps more difficult to accept it as a reasonable defence when there are repeated acts.

This can be illustrated by the case of The United States v. Brady8. The nine-year-old daughter of Brady’s girlfriend testified that he came into her bedroom wearing nothing, on a number of occasions. On one occasion she claimed Brady had pulled her hand into his ‘private area’ and another time he had intimately touched her.

In this case, both Brady’s mother and two ex-girlfriends provided witness testimony to help establish that he had an extensive history of sleepwalking — both as a child and an adult. Furthermore, his exes testified that, on occasion, he initiated sex with them while he was asleep.

In the eyes of the defence these accounts provided a strong argument that ‘sexsomia’ was a possible explanation for Brady’s alleged behaviour. However, neither these testimonies nor the opinion of a sleep expert — who also testified as to the possibility of sexsomnia — persuaded the authorities that Brady was innocent.

He was found guilty of two charges of indecency with a female under 16 years of age although, on appeal, one charge was set aside.

A note on the UK:

It’s worth noting that the English legal system deals with the concept of automatism in regards to sexsomnia differently to the US and Canada. Details can be found on the Crown Prosecution Service website here.

Can’t science prove that sexsomnia exists?

You might think it’s possible to measure such behaviour in the laboratory. But this isn’t as easy as you might imagine.

Polysomnography is not routinely performed as part of a medicolegal evaluation in part as this diagnostic tool is not associated with the crux of the legal focus upon mens rea with the criminal allegation 10.

To put this in layman’s terms, recording sleep behaviour (polysomnography) cannot offer evidence that the accused knew the act they committed was wrong (mens rea is Latin for guilty mind). So while there may be evidence of behaviours that would support the possibility of sexsomnia:

there is absolutely no after-the-fact polysomnograph finding that could possibly have any relevance as to whether the accused was sleepwalking at the time of the event in question.

What this means is that if you record someone’s sleep and discover that it’s normal then it doesn’t mean that it has always been normal — the accused person may have been experiencing sexsomnia in the past even if there’s no evidence for it in the present.

A good example can be seen in the case of State v. Scott8, where overnight sleep recording did not demonstrate unusual sexual behaviours in sleep. In this case, the court accepted an expert’s opinion that Scott exhibited ‘sexual behaviours in sleep parasomnia’ based on the defendant’s sleep history — as well as supporting evidence from family and sleep partners.

Even though the defendant’s sleep recording was normal — and might suggest the likelihood of a deliberate sexual assault — more importance was placed on the historical evidence. It was that evidence which exonerated Scott.

Sexsomnia as a defence: could it be an elaborate lie?

Because the diagnoses of sexsomnia are mainly based on the clinical history of the alleged offender — and given the lack of certainty from overnight sleep recordings — the sexsomnia defence can be seen as an opportune gambit.

It’s comparatively easy to claim sleep-disordered sexual behaviour as a defence when accused of sexual offences.

This is important in UK legal cases where the fact as to whether or not the sexsomnic episode is genuine is a key issue. On several occasions, people have been jailed when it is clear that their sexsomnia defence had no basis in law. Examples include:

  • A 2013 case when Simon Morris was sentenced to eight years in jail after the judge said the professional actor had told ‘an endless number of glib lies’.
  • Another 2013 case when businessman Gary Forbes pleaded sexsomnia after he was charged with raping a woman while on bail for an almost identical attack. He later dropped the defence and pleaded guilty.

As with all lies, the report of rare or improbable symptoms (like sexsomnia) — or unlikely symptom combinations — increases the likelihood that an individual is somewhat economical with the truth.


  • Sexsomnia is a relatively rare sleep disorder in which the sufferer initiates sexual behaviour while asleep.
  • In some cases, this may not be unwelcome but in other cases it can be extremely distressing and can be considered sexual assault.
  • If you feel as though you have been sexually assaulted, contact the police as soon as you are able.
  • Judicial systems around the world deal with the legal implications of sexsomnia differently.
  • It’s not unheard of for people who may not experience sexsomnia to fraudulently use it as a legal defence. This may be because it’s hard to prove someone has sexsomnia using conventional sleep analysis tools.


  • Andersen, M.L., Poyares, D., Alves, R.S., Skomro, R. and Tufik, S., 2007. Sexsomnia: abnormal sexual behaviour during sleep. Brain research reviews, 56(2), pp.271-282.

  • Shapiro, C.M., Trajanovic, N.N. and Fedoroff, J.P., 2003. Sexsomnia—a new parasomnia?. The Canadian Journal of Psychiatry, 48(5), pp.311-317.

  • Mangan, M. A. (2000). Sleepsex: Uncovered. Philadelphia: Xlibris

  • Schenck, C.H., 2015. Update on sexsomnia, sleep-related sexual seizures, and forensic implications. NeuroQuantology, 13(4).

  • Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 5th ed., American Psychiatric Association, 2013.

  • Davis, C., 2015. Sexsomnia–excusable or just insane?. Criminal Law Journal, 39(1), pp.21-39.

  • Organ, A. and Fedoroff, J.P., 2015. Sexsomnia: Sleep sex research and its legal implications. Current psychiatry reports, 17(5), p.34.

  • Mohebbi A, Holoyda BJ, Newman WJ. Sexsomnia as a Defense in Repeated Sex Crimes. The journal of the American Academy of Psychiatry and the Law. 2018 Mar;46(1):78-85

  • R. v. Luedecke, 2005 ONCJ 294

  • Bornemann MA. Sexsomnia: A medicolegal case-based approach in analyzing potential sleep-related abnormal sexual behaviors. InParasomnias 2013 (pp. 431-461). Springer, New York, NY.