Why do people sleepwalk, and should I wake them?

It tends to come an hour or two after bedtime, often while the adults are still up. There's a step on the landing, and there is your child, eyes open, looking straight through you. You may have asked what they were doing and got a flat, odd answer or none at all, or tried to shake them awake and met tears instead. Those open eyes are the unnerving part, because they make it look as though the person is there and choosing not to know you, when the part of them that would know you is still asleep.

That blankness is how sleepwalkingsleepwalking Getting up and moving about while still partly in deep sleep. The person usually remembers little or none of it. usually looks. A sleepwalker usually has open eyes and a blank face and can't answer you in the ordinary way. They do routine things for a few minutes, walking about or getting dressed, and won't remember any of it²⁴2 Irfan et al., 20214 NHS, 2025. Around five in every hundred children sleepwalk in a given year⁵5 Stallman & Kohler, 2016, and most grow out of it by their teens without any treatment¹⁴1 Mundt et al., 2023. In the meantime, there's something simple you can do the next time it comes.

What you met on the landing was someone walking who wasn't there. How does a body manage that while its owner sleeps? The story starts in deep sleepdeep sleep The slowest, most settled stage of sleep, when it’s hardest to wake someone. Most of it comes in the first part of the night., the hardest sleep of the night to wake from, which is most plentiful in the first few hours. Sleepwalking begins in a partial arousal from that deep stage, typically in the first third of the night¹²⁴1 Mundt et al., 20232 Irfan et al., 20214 NHS, 2025. That's why it so often comes not long after bedtime.

So why don't they simply wake up? What I find striking is how reluctantly deep sleep lets go. Someone in light sleep comes up within seconds, but deep sleep needs a much stronger push, and even then the sleeper comes up slowly, with a strong pull back down². That groggy, half-woken state is sometimes called sleep drunkenness, and it's close kin to sleep inertiasleep inertia The groggy, slow feeling just after waking, before the brain is fully up to speed.. A sleepwalker is someone caught partway along that slow climb. The parts of the brain that drive movement have come up into something like waking, while the parts for awareness and reasoning are still in deep sleep³⁶3 Idir et al., 20226 Terzaghi et al., 2009.

As researchers explain it, the brain's built-in programs for moving switch on while the regions for planning, judgment and memory stay switched off². That is the whole of the strangeness you saw: a body that can walk downstairs and open the fridge, guided by nothing that could ask whether it ought to, and keeping no record of the trip. It's how car keys end up in the fridge and furniture gets rearranged² by someone who will only learn of it the next morning, from whoever found them.

It can look that way, especially when someone mutters or seems to be searching for something. Most of the night's vivid, storylike dreams come later on, in REM sleepREM sleep Rapid eye movement sleep, often called dreaming sleep: the stage when most vivid dreaming happens. The eyes move quickly beneath the lids while most of the body’s muscles stay relaxed and still., and sleepwalking comes out of the deep sleep of the early night instead¹²1 Mundt et al., 20232 Irfan et al., 2021. Doctors describe it as coming with few or no dream pictures, and as leaving part or all of the episode unremembered².

Some adults do remember a fragment, and researchers don't fully agree on how much experience goes with an episode. In a Paris sleep clinic, researchers asked thirty-two adults with sleepwalking or sleep terrors what they recalled, both over their lives and on the morning after a night in the lab. Nine in ten could describe at least one dream-like experience they'd acted out, often an escape from some disaster, and in more than four in ten of those the scene was their own bedroom³⁷3 Idir et al., 20227 Uguccioni et al., 2013. So the danger was close by, in the very room they were sleeping in, and they ran from it. Those scenes were simpler than REM dreams, and the sleepwalkers mostly fled, where people with REM sleep behavior disorder mostly fought back⁷. That's a different condition, in which vivid dreams are acted out, and it often brings people to a doctor⁸8 Matar & Lewis, 2017.

Children weren't part of the study, though, and most people, children especially, wake with nothing to remember at all². For a parent, the useful part is this: your child came up out of deep sleep rather than the dreaming stage, so they probably aren't living out a troubled dream.

If your child screams and seems terrified rather than blank, that's likely a close cousin, the sleep terror. It begins with a sudden scream and intense fear, and it's most common in young children²⁹9 Petit et al., 2015. Trying to stop one tends to make it worse².

If you're wondering why your child, and why now, much of the answer is in the family and in their age. In Quebec, researchers followed nearly two thousand children from toddlerhood to age 13, and each year the mothers noted whether their child had sleepwalked. It was most common at age 10⁹9 Petit et al., 2015. Whether a parent had done it too made a great difference: when neither parent had ever sleepwalked, just over one in five children did at some point, and when both had, about three in five did⁹. A large study of Finnish twins points the same way, with genes accounting for a good share of who sleepwalks as a child³¹⁰3 Idir et al., 202210 Hublin et al., 1997, though the particular genes haven't been found yet³.

Going by those family figures, the tendency itself is largely a matter of family and age, and it isn't caused by anything you've done as a parent, in the choices you've made or the way you run your home. A run of short or irregular nights can set off episodes in a child who is already prone to them²2 Irfan et al., 2021. Those are the nights to watch, and why some nights bring it on is worth a look. Nor is sleepwalking in a child in itself a sign of a hidden psychological problem¹1 Mundt et al., 2023. Most children leave it behind on their own, and in one study it had stopped by age 13 in about three in four of them¹.

Families who live with it often notice that the bad nights come when someone is overtired, which is what researchers saw when they played sounds during deep sleep to ten adults who sleepwalk and ten who don't. On a normal night, three of the ten sleepwalkers got up into an episode; after being kept awake for twenty-five hours, all ten did, while none of the people who don't sleepwalk had one²¹³2 Irfan et al., 202113 Pilon et al., 2008. Missing sleep makes deep sleep pull harder, so when something disturbs it, the sleeper is more likely to come up only halfway. That only happens in someone already prone to sleepwalking.

You may have noticed your own pattern: the late night, the child coming down with something, the strange bed, the noisy house. Researchers sort what sets episodes off into two kinds. Noise, pain or pauses in breathing can break deep sleep up². Sleep loss or a body clock out of step can deepen its pull². Either kind makes an episode more likely in someone prone to it². Fever, stress and alcohol are often named as well, though the evidence for those comes mostly from what people report⁴¹²4 NHS, 202512 Lopez et al., 2013. This is the part you can do something about. Regular bedtimes and nights long enough leave fewer of the overtired nights when episodes come²¹³. In a large sleep-clinic series, mostly of adults, regular, sufficient sleep on its own brought partial or full relief to nearly one in five people who sleepwalked¹1 Mundt et al., 2023.

A sleepwalker moves with open eyes and no judgment, so the aim is a house where that does no harm. On nights it might happen, you could:

• keep doors and windows closed or locked²⁴2 Irfan et al., 20214 NHS, 2025
• put a gate at the top of the stairs, if it's a child who walks²⁴
• clear the landing and the floor of things to trip on²⁴
• lock away knives and tools²⁴
• keep a child who sleepwalks out of the top bunk²⁴

If they might leave the house, a door alarm is worth fitting⁴, ideally one that won't blare, since a sudden noise can itself set off an episode². None of this will stop an episode from starting, and it isn't meant to¹1 Mundt et al., 2023. Its work is to make sure a walk in the night ends back in bed, with nobody hurt.

If your child tends to walk at much the same time each night, you may hear of scheduled awakenings: waking the child briefly fifteen to thirty minutes before the usual time, each night for a few weeks¹²1 Mundt et al., 20232 Irfan et al., 2021. A handful of small reports found that children who tried it improved, though none of them followed other children who didn't, to see what would have happened anyway. Only one trial has set it beside something else in children, and it was small, with twenty children. One group was woken on a schedule and also kept to regular sleep and meal times, while in the other the parents were given explanation and reassurance alone. Both groups improved, and the trial found no clear difference between them, though twenty children are too few to rule one out¹, and the trial's author wondered whether the reassurance itself had been doing some of the work¹. If you're wondering whether to set an alarm, it's low-risk, though it's been studied only in children and only in small numbers. The families given reassurance alone improved too, and if the author's hunch is right, the steady explaining you're already doing may be doing some of the work.

For tonight, if you're still lying there listening, the timing is on your side. Sleepwalking belongs mostly to the first third of the night, when deep sleep is most plentiful¹²1 Mundt et al., 20232 Irfan et al., 2021, and the same strong pull that made them so hard to reach tends to draw a sleeper back down². The person you led back is most likely asleep again by now, remembering little or nothing of the landing or the kitchen²⁴4 NHS, 2025, and you can stop listening for footsteps and get some sleep yourself.