An extreme form of sleep-walking-having sex while asleep-is probably much more common than physicians have previously suspected, researchers reported here.

"The important message is that this is a real entity," said Colin Shapiro, M.B., ChB, Ph.D., of the University Health Network in Toronto at Sleep 2006, the joint meeting of the Sleep Research Society and the American Academy of Sleep Medicine.

"I look at it as one form of parasomnia," he said in an interview. "People walk in their sleep, they talk in their sleep, they drive their motorbikes in their sleep, they eat in their sleep, and they have sex in their sleep."

Dr. Shapiro and colleagues reported the results of an anonymous 28-item Internet survey that had 219 validated responses. "It's not huge," Dr. Shapiro said, and like all Internet research it has limitations, "but for me it's a proof of principle." A more directed survey, among 300 patients at Dr. Shapiro's Toronto sleep clinic, is under way, he said.

"The problem with an Internet survey," he said, "is that you don't know who you've surveyed." So, for instance, the researchers say they have no idea how prevalent sex during sleep—dubbed "sexomnia"-actually is among the general population.

On the other hand, the Internet survey appears to show that the problem-once thought to be predominately found in males-actually is more broadly distributed: Thirty-one percent of the 219 respondents were female.

The mean age-30.4 years-was relatively young, but respondents ranged in age from 15 to 67, Dr. Shapiro said.

One-hundred-eighty-six (84.9%) of the respondents identified themselves as heterosexual, 25 (11.4%) said they were homosexual, and six (2.7%) said they were bisexual. More than 92% said they had experienced multiple episodes of sexomnia, and a variety of sexual behaviors were reported, including 105 respondents—24 women and 81 men—who said they had had sexual intercourse while sleeping.

The most common precipitating factor, reported by 64 of the respondents, was physical contact with a bed partner, but other factors included alcohol, drugs, fatigue, and stress.

Sexual behavior during sleep is another form of parasomnia, and so deserves study, said Michael Silber, M.B., ChB, of the Mayo Clinic in Rochester, Minn., the president of the American Academy of Sleep Medicine.

Dr. Silber noted that sexomnia has "rather serious medical and legal implications" that make it an important topic of investigation.

The ramifications of sexomnia can be serious, Dr. Shapiro said, but only a minority of respondents reported legal complications. There were 13 respondents-10 men and three women-who reported sexual contact with minors. In most of the cases involving men, there were legal repercussions.

Dr. Shapiro said being asleep is a legal defense in some cases, but added that doctors and law enforcement officers have to "sift through" the case carefully before they can conclude that it's actually one of sexomnia, just as they must when other forms of parasomnia are presented as a legal defense.

He said he and colleagues recently reported a case in which a man claimed to have been sleep-walking when he committed murder; the researchers concluded the defense had no basis in the man's medical history.

Source: MedPage Today