A survey of 16,000 adults in 15 states found about 29 percent said they had sleepwalked at least once in their lives, close to three percent did it between once a year and once a month, and one percent sleepwalked at least twice per month.

"We did not know what was the prevalence of sleepwalking - as a disorder - in the general population, and that was a big problem," said Maurice Ohayon, director of the Stanford Sleep Epidemiology Research Center in California, who led the study, which appeared in the journal Neurology.

Past research on sleepwalking was mostly based on studies conducted in a lab, but Ohayon said he wanted to know what was actually happening in peoples' homes.

The survey asked participants about their lifestyle and sleeping habits, overall health and whether they had any sleep, mental or other types of disorders, including sleepwalking.

It found that certain people were more likely to sleepwalk, including those with sleep apnea or insomnia, heavy drinkers and people taking sleeping pills.

Participants on antidepressants known as selective serotonin reuptake inhibitors seemed to have a higher risk for sleepwalking, but the researchers said this could be explained by the conditions those drugs treat. Both major depression and OCD were also linked to sleepwalking.

Ohayon's team reported that close to one-third of sleepwalkers said they had a family history of sleepwalking .

"I'm not too surprised by the results," said Timothy Young, a neurologist and sleep medicine specialist with the Mayo Clinic Health System in Eau Claire, Wisconsin.

Young, who was not involved in the research, said that sleepwalking is thought to be common during childhood, but tapers off as people get older. Past studies have shown that 30 percent of children may be sleepwalkers, the researchers wrote.

According to Young, sleepwalking covers a spectrum of actions from sleep talking to getting out of bed. He told Reuters Health it becomes a problem when people start walking down stairs or outside.

The study was partially funded by the U.S. National Institutes of health, the Arrillaga Foundation, the Bing Foundation and Neurocrines Biosciences, which is a biopharmaceutical company.

SOURCE: bit.ly/JOxTg9

(Reporting from New York by Andrew Seaman at Reuters Health; Editing by Elaine Lies and Michael Perry)

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