Sleepwalking explained: What happens when your body moves while you're asleep

Sleepwalking, or somnambulism, is a sleep disorder in which a person gets up and moves around while still being asleep.

It most often occurs during deep sleep and can range from simple movements to complex behaviours, usually without any memory of the event afterwards.

While it may seem unusual or alarming, sleepwalking is generally harmless and is more common in children, though it can affect adults as well.

Firstpost spoke with sleep medicine specialist Dr Suresh Sagadevan from Gleneagles Hospital, who explained what actually happens in the brain and body when a person is sleepwalking.

What is sleepwalking and why does it occur?

Sleepwalking, or somnambulism, is a ‘disorder of arousal’ from deep sleep called N3 stage or slow-wave sleep. The brain is in a strange halfway state: the body’s motor system wakes up and starts walking, but the thinking, memory, and judgment part of the brain stays asleep.

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It’s surprisingly common. Globally, about 3.6 per cent of adults have at least one episode per year, while one to two per cent have frequent episodes. In children, it’s even higher - up to 17 per cent of kids aged three to 13 will sleepwalk at least once. Most kids outgrow it as the brain matures.

What actually happens to a person during an episode?

Imagine the body is on autopilot while the mind is offline. During an episode, a person can sit up, walk around the house, open doors, even drive - but they have no conscious awareness. Their eyes may be open, but they look ‘glazed’ and don’t respond normally.

The episode usually lasts 30 seconds to 30 minutes and ends when they go back to deep sleep. Next morning, they remember nothing. It’s not ‘acting out dreams’ - that’s REM Behavior Disorder. Sleepwalking happens in the first two-three hours of night, during deep non-REM sleep.

Common triggers for sleepwalking?

The brain needs "perfect conditions" to stay in deep sleep. Anything that fragments it can trigger sleepwalking.

Top 5 triggers I see include:

1. Sleep deprivation: Staying up late. Even two hours less sleep can double risk.

2. Fever/illness in children: This explains why kids sleepwalk more during viral fevers.

3. Stress and anxiety: This activates the brain during night.

4. Alcohol, sedatives, certain antidepressants: This disrupts sleep architecture.

5. Genetics: If one parent sleepwalked, child’s risk jumps to 45 per cent. If both parents did, risk is 60 per cent.

6. Sleep apnea is a hidden trigger in adults. Treating apnea often cures sleepwalking.

Is it dangerous? When to seek medical attention?

Yes, it can be dangerous because judgment is ‘asleep’. About 25 per cent of adult sleepwalkers have had an injury – falls, burns from kitchen, cutting themselves. Rare but real cases of violent behavior or driving accidents have been reported.

From my opinion, seek a sleep doctor if:

1.  Episodes cause injury to self/others

2. Person leaves home or drives while asleep

3. Episodes start suddenly in adulthood after age 25

4. It happens multiple nights per week and disrupts family sleep

5. Adults with new-onset sleepwalking need evaluation to rule out sleep apnea, seizures, or medication side effects.

Can it be prevented or managed?

Yes, 90 per cent of cases can be managed without heavy medication. The core is ‘sleep hygiene + safety’.

According to me, you must follow this prevention checklist:

1. Scheduled sleep: Seven to eight hours, same bedtime/wake time daily.

2. Avoid triggers: No alcohol/caffeine six hours before bed, manage stress

3. Safety-proof the room: Lock doors/windows, remove sharp objects, keep floor clear. Think ‘baby-proofing for adults’.

4. Treat underlying causes: If sleep apnea is present, CPAP therapy stops 70 per cent of adult sleepwalking cases.

For frequent, violent, or injurious cases, we use low-dose medications like clonazepam that suppress deep sleep arousals. But medicines are last resort. For children, most parents just need reassurance - 80 per cent outgrow it by teens.