Use of ‘sexsomnia’ defence is expected to increase in Ireland

DPP’s decision not to proceed with trial has highlighted the controversial condition

Sexsomnia has been a feature of rape trials in the UK for the past 15 years. File photograph: Getty Images

Sexsomnia has been a feature of rape trials in the UK for the past 15 years. File photograph: Getty Images


Sexsomnia, a controversial condition which causes sufferers to carry out sexual acts in their sleep, has been a feature of rape trials in the UK for the past 15 years but has never previously been successfully used as a defence in Ireland.

In the Central Criminal Court on Thursday, the office of the Director of Public Prosecutions said it will not be proceeding with the trial of a 31-year-old man accused of raping his friend after a night out while they shared a bed.

It was to be the third trial in the case. The first trial collapsed for legal reasons while the second resulted in a hung jury.

During those trials, the accused maintained he may have had sex with the woman but that it happened as a result of him suffering from sexsomnia, a controversial condition which causes people to perform sexual acts in their sleep.

The exact reasons for the DPP’s decision to drop the rape charge is unclear but it’s a safe assumption the sexsomnia defence used in the first two trials was a factor. After two failed attempts, lawyers for the State did not believe they had the evidence to secure a conviction.

The only other time the defence has been used in an Irish case was in 2012 during the trial of a man who sexually assaulted his cousin. He was later convicted and jailed.

Regular defence

But in the UK it has become such a regular defence in sex assault trials that prosecutors now sometimes don’t even bring a case to trial if the defendant can prove they suffer from the condition.

In 2013, a young man was charged with the rape of his friend in Manchester. From the outset, he claimed he suffered from sexsomnia, a claim supported by previous partners who had shared a bed with him.

His lawyers hired sleep experts who put him through the standard battery of tests for the condition; two nights’ sleep while wired up with electrodes and a third night of monitored sleep deprivation.

The examiners determined his brainwave patterns supported a diagnosis of sexsomnia. As a result, Crown Prosecution agreed to drop the case against him.

The defence has even worked when an accused faced multiple counts of rape. Last year, a Galway man was acquitted of raping his partner hundreds of times over the course of four years.

In legal terms, sexsomnia is an “automatism” defence; a defence where the accused admits to an act but says it was carried out without intent and without control of their actions.

It is differs from an insanity defence in that it usually relies on short-term phenomena like a concussion or sleepwalking rather than long-term mental disorders. In this case, the defence said the accused suffered from a condition which causes him to carry out sex acts, including full intercourse, while asleep.

The term sexsomnia was coined in 2003, although the more general defence of sleepwalking has been in use for far longer, most often in murder and manslaughter cases.


According to Prof Matthew Walker, a sleep science specialist in the UK, the condition is the result of a disconnect between part of the brain that deals with instinct and the part that deals with complex thought.

“It occurs in a state where the limbic system of the brain wakes up. This system deals with fright, flight, fight and also with other basics like the desire to eat and have sex,” he told The Irish Times. “Another part of the brain remains asleep; that is the frontal lobe which deals with social context and planning.”

The engine is running but there’s no driver behind the wheel, was how defence counsel Hugh Hartnett put it for the jury during one of the previous trials.

Noeline Blackwell of the Rape Crisis Centre said it is a very difficult issue, one which psychiatrists are probably better equipped to deal with than lawyers.

“I absolutely understand that if somebody doesn’t have the intent to commit a crime they can use this defence.”

But she said any claims of sexsomnia must be strong tested by the prosecution.

“The area of psychiatry is one of the most interesting areas in the area of crime. We are moving on more and more in understanding what happens with the brain. But you have to ask as well, what can it justify?”

According to barrister Fergal Foley, the decision to drop the charges could result in a short term increase in sexsomnia or automatism being used as a defence in rape trials.

“Anytime anything new happens like this there’s always a bandwagon effect and people try and climb on,” he said. “Then what usually happens is it starts rolling back a bit because people realise it’s not a get-out-of-jail-free card.”


It’s an “eyebrow-raising case”, said another barrister who asked not to be identified. “But the amount of future cases it’s going to be used in is unlikely to increase dramatically. I think there is a general view among lawyers that juries don’t like automatism. They don’t believe in it and they’d be very sceptical of a defendant running it.”

There is also the issue of alcohol, which features in the majority of rape cases before the courts.

“It might be assumed that now people can drink themselves into a stupor and get away with anything they do,” the lawyer said. “That’s not the case, the law is against it.”

Even if a person can prove they were an automaton, the defence will fail if the condition was caused directly by alcohol. This is the result of a 2004 case in which the Court of Criminal Appeal ruled that a man who stabbed an 18-month-old child to death while sleepwalking was guilty because the sleepwalking was caused by his alcohol intake.

Another hurdle is that sexsomnia is a difficult disorder to diagnose and doctors approach it with a degree of scepticism.

“We usually bring them into hospital overnight and record them,” said Prof Walker. “But they may not have an episode. Sometimes we may induce episodes by sleep depriving people before they come in. The fact that we don’t record episodes doesn’t mean people don’t have it as it can be quite a rare occurrence.”

Ethical difficulties

There are also practical and ethical difficulties in diagnosing sexsomnia. Doctors can’t put someone in the bed next to a subject and wait for a sexual assault to occur. As a result, much of the evidence of sexsomnia relies on the word of the subject and their partners. However, Prof Walker believes it is also a difficult condition to fake.

“The concern always is people are going to be using it to excuse things they’ve done but there are usually a number of tell-tale symptoms that enable us to make a diagnosis with some confidence. It would take quite a lot of planning to fake it.”

The defence of sexsomnia in this week’s case was built on strong foundations. There was evidence the accused had been sleepwalking since childhood and has a family history of sleepwalking - both of which can predicate sexsomnia, according to experts.

There was also evidence from a former girlfriend and two friends who said he had groped and grinded against them in his sleep. Furthermore, two sleep experts with 30 years of experience said it was likely he had sexsomnia at the time of the incident.

Despite a general acceptance by the medical community, sexsomnia remains controversial. Dr Harry Kennedy, the clinical director of the Central Mental Hospital, told the trial there has been no observed case of someone initiating and carrying out sexual intercourse with another. All of the cases cited in the literature rely on the patients’ word, he said.

He told a previous trial it was impossible for a person to carry out “complex, sequential, goal-orientated” acts, such as removing a person’s clothes, while asleep.

In response, the defence pointed to the Diagnostic and Statistical Manual of Mental Disorders, the “bible” of psychological diagnosis, which states that sex is possible during sleep and can encompass complex actions.

The defence of sexsomnia will make many people uncomfortable; particularly the idea that a woman can be raped but the man who did it is not a rapist. But it is important to note this will not be a get out of jail free card for future rape accused.

While the man in this week’s case is innocent in the eyes of the law, the decision of the DPP to drop the charge means sexsomnia has yet to be accepted by an Irish jury. But if UK trends are anything to go by, it will not be long before the issue arises again.