Although only a handful of people in the United States sleepwalk every year, a new study suggests close to one-third may do it at some point in their lives.
The study, published in the journal Neurology, also suggests that other sleep disorders, severe depression and obsessive-compulsive disorder (OCD) – among other things – are linked to an increased chance of sleepwalking.
Past research on sleepwalking was mostly based on studies conducted in a lab, according to the study's lead author, who said he wanted to know what was actually happening in people's homes.
"We did not know what was the prevalence of sleepwalking as a disorder in the general population and that was a big problem," said Dr Maurice Ohayon, director of the Stanford Sleep Epidemiology Research Centre in California.
Results not surprising
To find out how many people are prone to nocturnal wandering at home, Dr Ohayon and his fellow researchers from around the US called about 16 000 adults in 15 states.
They asked all of the participants a series of questions about their lifestyle and sleeping habits, their overall health and whether they had any sleep, mental or other types of disorders – including sleepwalking.
Overall, about 29% said they had sleepwalked at least once in their lives. Close to 3% said they currently did it between once a year and once a month, and 1% said they sleepwalked at least twice per month.
"I'm not too surprised by the results," said Dr Timothy Young, a neurologist and sleep medicine specialist with the Mayo Clinic Health System in Eau Claire, Wisconsin.
Sleepwalking common during childhood
Dr Young, who was not involved with the new research, said that sleepwalking is thought to be common during childhood, but tapers off as people get older.
Past studies have shown that 30% of children may be sleepwalkers, the researchers wrote.
They found certain people were more likely to sleepwalk, including those with sleep apnoea or insomnia, heavy drinkers and people taking sleeping pills.
Participants on 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.
Dr Ohayon's team reported that close to one-third of sleepwalkers said they had a family history of the sleep disorder.
Ignore the myths
Dr Young said it's important to ignore the myth about waking someone up when they're sleepwalking.
"What we say is, redirect the person and get them back to bed," he said.
As for prevention, he said it's important to avoid what triggers a specific person's sleepwalking episodes and to make sure their bedroom is cleared of anything they may hurt themselves with.
The new study was partially funded the US National Institutes of Health, the Arrillaga Foundation, the Bing Foundation and biopharmaceutical company Neurocrines Biosciences.
It's also important to note that these results are based on what the participants reported themselves, the researchers said. Sleepwalking, they added, may be underreported since forgetting the event is characteristic of the disorder.
(Andrew M. Seaman, Reuters Health, May 2012)