Sleepwalking affects 3.6 per cent of adults in the U.S., more than previously thought, a new study suggests.

Dr. Maurice Ohayon, a professor of psychiatry and behavioral sciences at Stanford University, and his co-authors set out to estimate the prevalence of sleepwalking in the U.S., since the most recent research on the topic was done 10 years ago in Europe. The only U.S. sleepwalking prevelance rate study was published 30 years ago. That study reported a prevalence of 2.5 per cent of sleepwalking in a sample of 1,006 adults living in the Los Angeles metropolitan area.

"This study, based on a large representative sample of the U.S. general population, is the first to demonstrate the prevalence of nocturnal wandering in the community," Ohayon and his co-authors concluded in Tuesday's issue of the journal Neurology.

"Precisely, 3.6 per cent of the sample had more than one episode of nocturnal wandering in the previous year."

The researchers surveyed nearly 19,136 individuals from 15 states by phone to gather information on participants' mental health, medical history and medication use.

SEE: 12 Steps To Better Sleep. Story continues below:

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  • Unplug

    Cozying up to your beloved laptop in bed or nodding off to Jimmy Fallon could disrupt your zzz's. Not only is the content on the screen stimulating, but electronics emit a blue hue that mimics daylight. "It stops your body from producing the sleep hormone melatonin," says Pete Bils, vice chair of the Better Sleep council. As a rule, turn off all gadgets at least one hour before bedtime; true screen addicts can download the <a href="http://stereopsis.com/flux/" target="_hplink">F.lux app</a> to your computer -- it'll dim the screen as it gets later. <br><br> <strong>More from Shape.com:</strong><br> <a href="http://www.shape.com/lifestyle/mind-and-body/8-simple-ways-detox-your-body" target="_hplink">8 Simple Ways to Detox Your Body</a> <br> <a href="http://www.shape.com/lifestyle/mind-and-body/5-easy-home-allergy-remedies" target="_hplink">5 Easy At Home Allergy Remedies</a> <br> <a href="http://www.shape.com/lifestyle/mind-and-body/6-reasons-you-need-more-sleep" target="_hplink">6 Reasons You Need More Sleep</a> <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/xelcise/4475036638/" target="_hplink">Xelcise</a></em>

  • Ease Up On Caffeine

    Whether your drug of choice is diet cola, dark chocolate or skim lattes, it's time to pull back. Caffeine lingers in your system for up to 12 hours, so that 3 p.m. java can still have a hold on you come bedtime. When coffee cravings hit after noon, reach for a cup of decaf, says Phyllis C. Zee, M.D., Ph.D., the director of the Sleep Disorders Program at Northwestern University. If you're desperate for an energy boost, try going for a brisk walk around the block instead of drinking that cup of joe. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/mezzoblue/40001562/" target="_hplink">mezzoblue</a></em>

  • Don't Over-Hydrate

    Sucking down too much liquid in the evening is a sure-fire way to guarantee rest-wrecking midnight bathroom trips. Even though your body helps by naturally reducing urine production during sleep, it's a good idea to cut off liquids at least one hour prior to going to bed. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/widnr/6589979029/" target="_hplink">Wisconsin Department of Natural Resources</a></em>

  • Build A Great Nest

    Considering how many hours you spend in your bed, it might be overdue for an upgrade. First, the mattress: The most common bedding mistake people make, says Zee, is not replacing it often enough. Most can last about five to 10 years; if yours is sagging, it's probably already past its prime. When buying sheets, make breathability the top priority. "Your body's temperature changes as you move through different sleep stages," says Zee, "so you need sheets that can handle the fluctuations." Go for natural fibers like cotton and silk, or try the new high-tech bedding made from moisture-wicking fabrics, such as sheex (sets from $159; sheex.com). The right pillow -- down vs. poly, flat vs. full -- is also key to nighttime comfort. For a customized fit, try the pillowology line (from $130; sleepnumber.com). <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/play4smee/3334798166/" target="_hplink">play4smee</a></em>

  • Keep Your Cool

    Set the thermostat to around 65°F, plus or minus five degrees. "That's the range in which your body can stay comfortable without having to do anything, like shiver to heat itself up or perspire to cool down," says Bils. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/besharatian/6371002249/" target="_hplink">faz besharatian</a></em>

  • Hit The Gym In The A.M.

    "Exercise reduces stress, so it's good for sleep, but it also increases your body's core temperature, making it tough to drift off," says Robert Oexman, director of the Sleep to Live Institute in Joplin, MO. A recent study presented to the American College of Sports Medicine found that 7 a.m. workouts improved sleep quality more than late-day exercise. If you can't give up your 7 p.m. spin class, take a steamy shower afterward. It sounds counterintuitive, but heating your skin and then stepping into the air makes your core cool down quickly -- a cue to your body that it's time to drift off. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/28009451@N03/4385990305/" target="_hplink">dmjarvey</a></em>

  • Make Your Bed

    Once you've got your pretty new threads, don't leave them in a heap when you get up in the morning. Aesthetics aside, taking a moment to tidy up may help you sleep better at night. In fact, 44 percent of people who make their beds daily report snoozing more soundly than those who don't, according to the National Sleep Foundation. Researchers speculate that a messy room can make you feel more stressed and restless. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/jek-a-go-go/4024221828/" target="_hplink">jessica wilson {jek in the box}</a></em>

  • Get Up On Sundays

    Sleeping in on weekends only seems like a dreamy idea. "Wide variations in your get-out-of-bed time can throw off your sleep-wake cycle, putting you at risk for insomnia," says Joseph Ojile, M.D., director of the Clayton Sleep Institute in Maplewood, MO. If you're dying to sneak in extra rest, keep it to within an hour of your weekday wake-up time. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/piermario/3871642211/" target="_hplink">piermario</a></em>

  • Nix The Nightcap

    If you think alcohol can help you fall asleep, you're only partially right. "You may seemingly slip into a peaceful slumber, but alcohol gets in the way of the deep, quality rest your body needs," says Zee. You don't have to swear off all spirits, but limit yourself to one glass per night and consume it at least three hours before turning in. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/zoxcleb/5972503674/" target="_hplink">zoxcleb</a></em>

  • Swap Warm Milk For Cherry Juice

    Milk does have small amounts of tryptophan, the hormone that induces sleep. But if the beverage leaves you cold, opt for an evening and morning glass of tart cherry juice, which contains the sleep hormone melatonin. According to a British study, people who drink it regularly sleep longer (an extra 25 minutes) and more deeply than those who don't. <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/appelogen/3585356104/" target="_hplink">appelogen.be</a></em>

  • Follow Your Nose

    The scent of lavender may improve your sleep quality, according to a study conducted at Wesleyan University. Researchers found that people who took a whiff of lavender oil before going to bed spent more time in deep slumber and awoke feeling more energetic than those who sniffed plain water. Try Good home Co. Sheet & Clothing Spray in lavender (from $12; goodhomestore.com) or Bath & Body Works aromatherapy pillow mist ($10; bathandbodyworks.com). <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/rutgersmit/38040046/" target="_hplink">//Rutger</a></em>

  • Seek A Pro's Help

    If all else fails -- meaning you've been battling insomnia for more than a month or you often feel groggy despite spending seven-plus hours in the sack -- a specially trained doctor can help you pinpoint the problem and suggest an appropriate treatment. Depending on what's plaguing you, you might benefit from cognitive behavioral therapy, herbal remedies, prescription medication or treatment for a condition like sleep apnea. To find a sleep professional, go to sleepfoundation.org. <br><br> <strong>More from Shape.com:</strong><br> <a href="http://www.shape.com/lifestyle/mind-and-body/8-simple-ways-detox-your-body" target="_hplink">8 Simple Ways to Detox Your Body</a> <br> <a href="http://www.shape.com/lifestyle/mind-and-body/5-easy-home-allergy-remedies" target="_hplink">5 Easy At Home Allergy Remedies</a> <br> <a href="http://www.shape.com/lifestyle/mind-and-body/6-reasons-you-need-more-sleep" target="_hplink">6 Reasons You Need More Sleep</a> <br><br> <em>Flickr photo by <a href="http://www.flickr.com/photos/bandidoofoz/706795160/" target="_hplink">Bandido of Oz</a></em>

  • Related Video

The participants were asked about the frequency of episodes of sleepwalking, how long any sleep disorders lasted and about any inappropriate or potentially dangerous behaviours during sleep.

Sleepwalking episode may not be remembered
When respondents' answers about episodes of sleepwalking during childhood or adolescence were included, the lifetime prevalence of sleepwalking was 29.2 per cent.

What's not known is whether medical conditions provoke sleepwalking or vice-versa, Ohayon said.

Among those who reported sleepwalking, it was mainly chronic. About 7.2 per cent of respondents had episodes for less than six months, 5.8 per cent for 6 to 12 months, and another 6.2 per cent had it for one to five years and 80.2 per cent for more than five years.

Nearly 40 per cent of the respondents worked a day-time shift.

Other findings included:
Sleepwalking was not associated with gender and seemed to decrease with age.
Nearly one-third of individuals with nocturnal wandering had a family history of the disorder.
People with depression were 3.5 times more likely to sleepwalk than those without.
People with alcohol abuse or dependence or obsessive-compulsive disorder were also significantly more likely to have sleepwalking episodes.
People using over-the-counter sleeping pills had a higher likelihood of reporting sleepwalking episodes at least two times per month.
In most of the cases of sleepwalking among those taking psychotropic medication, such as antidepressants or hypnotics, the patient was awake but confused and did not remember the episode after waking up.

"It seems unlikely that these medications cause nocturnal wandering, but rather that they appear to trigger events in predisposed individuals," the researchers said.

Since there is no objective measure of sleepwalking, and amnesia is a characteristic, it is likely that sleepwalking is underreported, especially among those living alone, they concluded.

The study was funded by the U.S. National Institutes of Health, the Arrillaga Foundation, the Bing Foundation and an educational grant from Neurocrines Biosciences.

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