By Elizabeth Landau
(CNN) -- Sleepwalking isn't just a quirk of Homer Simpson and other cartoon characters who go on unconscious adventures. New research suggests it's even more common than you may think.
Researchers published a study in the journal Neurology involving more than 19,000 American adults, and found that nearly 30% had sleepwalked at some point in their lives. Far fewer said they experienced sleepwalking within the last year - only about 4% did. One percent had two or more episodes per month.
Dr. Maurice Ohayon of Stanford University and lead author of the study says sleepwalking can be risky business; some people can harm themselves or others while wandering about.
Sleepwalking is far more likely to occur in childhood than adulthood; previous research suggests that as many as 30% of children have been affected.
Prior to this study, there was no good estimate of how many Americans sleepwalk generally, the researchers wrote. A study 10 years ago in Europe found a prevalence of 2%. And 30 years ago, a study in Los Angeles found about 2.5% of about 1,000 people experienced sleepwalking.
There wasn't a significant difference in sleepwalking in men vs. women, but the behavior did decrease with age, with the exception of those who reported it more than once per week.
Family history and genetics may play a role: 11.4% of people who reported sleepwalking said at least one sibling had episodes, compared to 7.8% of the rest of the participants. Individuals who said they sleepwalked in the previous year were more likely than others to have had a family history of sleepwalking.
The study authors also took into account participants' usage of medications for sleep, anxiety, depression and other purposes. They found that people who take a kind of antidepressant for anxiety called SSRI (selective serotonin reuptake inhibitor) had a higher likelihood of sleepwalking at least once per year. Those who took over-the-counter sleeping pills and tricyclic antidepressants were more likely to experience sleepwalking at least twice per month.
Although previous studies have suggested that psychotropic medications are associated with sleepwalking, this one suggests that pills don't cause nighttime wandering per se; however, they may trigger these behaviors in people already predisposed, study authors wrote.
But keep in mind that the results are based on people's own recollections and knowledge of their sleepwalking behaviors; the researchers did not independently confirm the participants' sleepwalking accounts. Furthermore, some people, particularly those who live alone, may engage in sleepwalking without being aware of it. So the researchers may have underestimated sleepwalking behaviors.
Dr. Lisa Shives, founder of Northshore Sleep Medicine in Evanston, Illinois, said the study's estimate of 30% of people with at least one sleepwalking episode in their lives sounds about right. People do tend to outgrow sleepwalking after their teenage years, but there remains a minority who continue to have recurrent episodes.
There have been some bizarre incidents recorded of people's behavior while sleeping. One woman was reported to have sex with strangers during sleepwalking episodes. Sleepwalking has also been used as a legal defense, sometimes successfully, for people who have allegedly committed crimes while sleeping.
"You really need a strong documented history that somebody has been doing this for a while" for sleepwalking to be a believable defense in court, Shives said.
The precise causes are still mysterious, partly because sleepwalking is so hard to study. Shives has had patients who are chronic sleepwalkers normally, but don't exhibit the behavior in the laboratory.
It's important to focus on safety measures for people prone to sleepwalking, Shives said. Lock doors and windows at night. Kitchen knives and other sharp objects may even need to be put away at night. You may need an alarm system for exits.
Some lifestyle modifications may help, such as having a regular sleep schedule, reducing noise or light in the place where you sleep, and avoiding stress and fever. Hypnosis may help get rid of their sleepwalking behaviors. Another treatment that may help is called "anticipatory awakenings," where the person is awakened about 15 minutes before they would normally sleepwalk and stay awake during that period. Benzodiazepine medications have also been prescribed.
And take note: It's a myth that waking a sleepwalker would result in brain shock or death; the person may be startled or disoriented, but waking him or her up could save the person from doing serious harm. Still, some experts recommend gently guiding the sleepwalker back to bed if possible.