STANFORD, Calif. - In a new study, Stanford researchers describe a treatable medical condition which causes people to commit violent sexual acts in their sleep. Referred to as "sleep sex," the nocturnal activities cited in the study range from disruptive moaning to rape-like behavior toward bed partners.

The researchers believe this condition stems from glitches in brain waves during sleep. By bringing attention to the disorder, they hope the health-care community will recognize the problem as medical in origin rather than psychological. "Now doctors might know to ask patients about how they're sleeping," said Christian Guilleminault, MD, professor of psychiatry and behavioral sciences at the Stanford School of Medicine.

Guilleminault's study, released in the March/April issue of the journal Psychosomatic Medicine, outlined 11 patients with symptoms that included loud, disruptive moaning on one end of the scale and sexual assault on the other. Regardless of how unusual or violent the behavior, patients had no memory of the events the next morning.

Guilleminault divided the patients into three groups depending on the severity of their behavior. Those whose disturbances were simply annoying included two women who made sexual moaning sounds during the night. Though relatively harmless, one woman felt embarrassed and guilty that her moaning disturbed her spouse and children.

The second group consisted of a man and a woman whose disturbances placed them at physical risk. They experienced periods of violent masturbation that left bruising or soreness. The man also reported breaking two fingers trying to escape from restraints he had used to prevent the behavior.

The third group included six men and one woman who made unwanted - and sometimes violent - sexual advances on their bed partners while asleep. In one case, the patient tried to strangle his wife. A teenage child in the home heard the disturbance and called the police, eventually leading to a referral to the Stanford Sleep Clinic.

"What was surprising was the duration of the abnormal behavior and the fact that people weren't reporting it," Guilleminault said. One patient in the study had been aware of the unusual behavior for 15 years before talking about it with his doctor. "People have to realize that it's a medical problem and there is a treatment," he said.

Over the past 10 years, researchers have suspected that violent behavior during sleep is a sleep-related disorder, but they didn't have the facts to prove it. Although these cases sound psychological in origin, Guilleminault believes the underlying problem relates to sleep. Rather than quietly passing through the five phases of sleep - each of which has a classic brain-wave pattern - the patients in the study had unusual patterns during one of the sleep phases or short interruptions in their sleep. Sound and video recordings of the patients showed that the sleep-sex behavior took place during these hiccups in the sleep cycle. In addition, seven of the patients had a history of walking in their sleep.

In all cases except one, the sleep disturbances went away with sleep disorder treatments - the same ones that would prevent sleepwalkers from raiding the fridge at night. Therapy includes drugs in the same family as Valium and treatments used for breathing disturbances.

Guilleminault said each of the patients had additional emotional problems that may have altered the form their sleep disturbance took. "What your state of mind is will color the presentation," he said. But even if the patients had no emotional problems, he added, the underlying sleep disorder still would exist, though it may take the form of sleepwalking or talking in sleep.

Guilleminault added that because the sleep disorders were embarrassing, sufferers were less likely to complain and also didn't know where to turn for help with the problem. "The aggressor and the victim are often both in difficult situations and don't know how to express the problem," he said. "They feel that there is nowhere to turn."

---Stanford University Medical Center

Back to The Science of Mental Health