Nobody is fully in control of their body or mind when they sleep. It’s common for people to snore or occasionally talk in their sleep, or to have dreams that inexplicably combine real-life and imaginary events. Upon waking up, you might vividly recall portions of a dream, just the faintest snippets, or nothing at all. One of the most puzzling, and potentially dangerous, nocturnal behaviors is sleepwalking. Unknowingly getting up, and sometimes performing complicated tasks, is an especially unsettling way to lose control of your body.

We’ll take a look at what causes sleepwalking, but first, let’s define what it is and its prevalence.

What Is Sleepwalking?

The medical term is “somnambulism,” which involves a person getting up and walking around while in a state of deep sleep, according to the Mayo Clinic. Sleepwalking is most common in children, with most growing out of it by the time they reach puberty. A typical episode occurs one to three hours after falling asleep and lasts fewer than 10 minutes, sometimes ending within a few seconds. The person may sit up in bed and look around with a blank expression on their face, rub their eyes, or tug on their pajamas. They may get out of bed and walk around with their eyes open. The sleepwalker may engage in normal activities such as getting dressed, eating or urinating but may do so in a clumsy or inappropriate way — for example, eating pet food or urinating in the closet.

Since they are in a deep state of sleep, the sleepwalker typically will not respond when spoken to or may respond incoherently. The person may return to bed on their own, with or without waking up confused, or may be gently coaxed back to bed. Whenever possible, experts advise against waking a sleepwalker, as they may react with fear, confusion or anger. If the sleepwalker can return to bed without waking up, they will typically have no memory of the event.

As Current Biology reports, it’s estimated that 17% of children sleepwalk, and 2% to 4% of adults regularly sleepwalk or engage in related behaviors. It’s quite common for people to sleepwalk occasionally, with 29% of adults experiencing at least one episode in their lifetime, which is often related to the use of sleeping pills or antidepressants.

If you have a sleepwalker in your home, preventing injury should be a top priority. Keep guns and knives out of reach. Close and lock windows and doors as appropriate, and use safety gates at the tops of stairs. Remove tripping hazards and other potentially harmful objects. These measures are usually sufficient for the occasional sleepwalker. However, a serious discussion with a medical professional is recommended if the episodes are frequent (e.g., one to two times a week), prolonged or likely to result in serious injury. For example, some sleepwalkers will leave the house and even attempt to drive a car.

What Causes Sleepwalking?

The immediate cause of somnambulism is still unknown, but there is a clear genetic component. About 22% of children whose parents have no history of this behavior will sleepwalk, according to the Sleep Foundation. That number rises to 47% if one parent has a history of sleepwalking or 61% if both parents were known to sleepwalk.

Sleepwalking occurs during the deepest phase of sleep. According to StatPearls, the four stages of human sleep are N1, N2, N3 and rapid eye movement (REM) sleep. N1, N2 and N3 are stages of non-rapid eye movement (NREM) sleep. The human body cycles through all these stages four to five times each night, averaging about 90 minutes per cycle.

N1 is the first and lightest stage of sleep and usually lasts just one to five minutes. Everything starts to slow down, including eye movements and muscle activity. N2 is a deeper sleep, when heart rate and body temperature drop. This stage is important for consolidating memory. Eye movement stops, and teeth grinding may occur. N2 may last 25 minutes in the first cycle and lengthen with each successive cycle.

N3 is the deepest stage of non-REM sleep, and there is usually no eye movement or muscle activity. This is also the stage when sleepwalking, night terrors and bedwetting occur. Individuals forced to wake up during this stage tend to be “groggy” — with moderately impaired mental performance for up to an hour. As people age, they tend to spend less time in this stage and more time in N2.

Finally, REM sleep is associated with vivid dreams and rapid eye movement. The legs and arms become temporarily paralyzed, but heart rate increases and the brain is highly active. The first REM period typically lasts 10 minutes, with the final one lasting up to an hour. In the morning, people tend to wake up spontaneously during REM sleep.

Children are more prone to sleepwalking because their brains are still developing, and they spend more time in deep N3 sleep.

Contributing Factors

Regardless of age, people are more likely to sleepwalk when they are extremely fatigued, probably because they are spending more time in deep sleep. Other factors that increase the risk of sleepwalking are associated with disruptions in sleep, such as stress and anxiety, sudden noises or touches, illness, fever or going to sleep with a full bladder. Migraines, drinking too much alcohol and certain medications can also trigger an episode. Restless legs syndrome and obstructive sleep apnea (pauses in a person’s breathing pattern) are also common culprits. Any underlying medical issues should be treated to reduce somnambulism.

For some sleepwalkers, relatively straightforward measures can decrease the likelihood of an episode:

• Keep a regular sleep schedule.
• Reduce stress.
• Ensure the room is dark, quiet and comfortable for sleeping.
• Limit drinks and caffeine in the evening.
• Use the toilet before bedtime.

If those options fail, sleepwalkers may benefit from therapy or medications.

Researchers are still working to understand what fully causes sleepwalking, so it may take some time for a patient’s physician to tailor an effective strategy to combat this potentially dangerous sleep disorder.

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