May 14, 2012 -- Do you remember exactly where you were last night? If you are a sleepwalker, maybe not.
Sleepwalking may be more common than experts have estimated, says a California psychiatrist.
"The numbers are very big," says researcher Maurice Ohayon, MD, PhD, DSc, professor of psychiatry and behavioral sciences and director of the Stanford University Sleep Epidemiology Research Center.
In his poll of nearly 16,000 adults, he found nearly 30% reported a history of sleepwalking. That included episodes in childhood and adolescence.
In the previous year, 3.6% said they had sleepwalked at least once. That is estimated to be about 8.5 million adults.
Studies on the number of sleepwalkers are sparse, Ohayon tells WebMD. In one of the few studies done in adults and published 30 years ago, past researchers found 2.5% sleepwalked. Those more likely to sleepwalk were on certain medicines, including some antidepressants, Ohayon found in his current study. They were more likely to have certain disorders, including obsessive-compulsive disorder, he says.
The study is published in the journal Neurology.
Sleepwalking: Poll Details
Sleepwalking is more common in childhood than later in life. Up to 30% of children sleepwalk at some time, Ohayon says.
Exactly why some people sleepwalk and others do not is not known, Ohayon tells WebMD.
Ohayon says his study is the first to use such a large sample of the U.S. adult population. His team conducted phone interviews with men and women, aged 18 to 102. They lived in 15 states.
They answered questions about sleepwalking history, medicine use, other sleep habits, and medical conditions.
More than 30% said other members of the family also were sleepwalkers.
Certain medical conditions, Ohayon found, were linked to sleepwalking.
- Sleep disorders such as sleep apnea, in which people have abnormal pauses in breathing during the night
- Alcohol abuse or dependence
- Obsessive-compulsive disorder
People taking antidepressants known as SSRIs had more than twice the odds of sleepwalking, Ohayon says. SSRIs include drugs such as Celexa, Lexapro, Paxil, Prozac, and Zoloft. Those on over-the-counter sleeping pills boosted risk, too. "You have a two and a half times higher chance of sleepwalking if you are taking an over-the-counter sleeping pill with diphenhydramine," he says.
The big surprise, Ohayon says, is that he found no link between prescription sleeping pills and sleepwalking. Other research has found such a link.
Sleepwalking Statistics: Perspective
The new study "adds more concrete numbers" to sleepwalking statistics, says Gayatri Devi, MD, an attending neurologist at Lenox Hill Hospital. She is also clinical associate professor of neurology at NYU School of Medicine.
She reviewed the findings for WebMD.
Some past estimates have said that as many as 10% of people sleepwalk at least once in their lifetime, Devi says.
She, too, is surprised that no link was found between prescription sleeping pills and sleepwalking. It could be, she says, that fewer people were taking the prescription medicines than over-the-counter, so the link showed up more clearly with the nonprescription medicines.
"Even though this study did not find an association between prescription sleep medicines and sleepwalking, the fact is, it's pretty well known that the prescription sleeping aids affect sleep architecture," she says. Anything that affects sleep architecture (or sleep pattern and structure) can increase sleepwalking, she says.
Handling a Sleepwalker
What should you do if someone is sleepwalking? "Make sure they are safe," Devi says. "If at all possible, gently try to steer them toward their bed. If they resist, let them be."
Ohayon adds: "Make sure there is a lock on the door and the window. They don't realize what they are doing."