Sleepwalking happens when part of your brain wakes up while the rest stays asleep. During deep sleep, the regions responsible for movement and emotion activate as if you’re awake, while the areas that handle awareness, judgment, and memory remain shut down. This split state lets a person get up, walk around, and even perform complex actions with no conscious control and no memory of it afterward. About 29% of children sleepwalk at some point, and roughly 1.5% of adults still experience episodes in any given year.
A Brain Caught Between Sleep and Waking
Sleepwalking occurs during the deepest stage of non-REM sleep, typically in the first third of the night. Brain imaging studies reveal a striking pattern during episodes: the motor cortex (which controls movement), the cingulate cortex (involved in emotion and basic decision-making), and the cerebellum (which coordinates physical actions) all light up with activity that looks identical to wakefulness. At the same time, the frontoparietal association areas, the parts of the brain responsible for rational thought, self-awareness, and processing your surroundings, show even deeper sleep activity than normal.
This is why a sleepwalker can navigate a hallway or open a door but has a blank, staring face and can’t hold a conversation. The prefrontal cortex, which you need for conscious awareness and forming memories, gets almost no blood flow during an episode. That explains the near-total amnesia afterward. The thalamus, a relay station that normally goes quiet during deep sleep, stays unusually active during sleepwalking, which may be what allows sensory and motor signals to pass through even though higher-level thinking is offline.
Genetics Play a Major Role
Sleepwalking runs strongly in families. A large longitudinal study published in JAMA Pediatrics found that children with one sleepwalking parent were significantly more likely to sleepwalk themselves. Researchers have identified a specific immune-system gene variant, HLA DQB1*05:01, that appears in about 41% of people with sleepwalking and related disorders, compared to roughly 24% of the general population. This genetic marker doesn’t cause sleepwalking directly, but it suggests a shared biological vulnerability that makes the brain more prone to these incomplete arousals during deep sleep.
The genetic link also helps explain why sleepwalking, sleep terrors, and confusional arousals often cluster in the same families. These conditions are all classified as disorders of arousal from non-REM sleep, and the same gene variant is associated with all of them regardless of subtype. If you sleepwalked as a child, you carry that predisposition for life, even if episodes become less frequent with age.
Common Triggers for Episodes
Having the genetic predisposition loads the gun, but specific triggers pull the trigger. Anything that deepens sleep, fragments sleep, or forces the brain into a partial arousal can set off an episode.
- Sleep deprivation is one of the most reliable triggers. When you’re overtired, your brain compensates by spending more time in deep slow-wave sleep, which is exactly the stage where sleepwalking occurs.
- Alcohol fragments sleep architecture and can provoke partial arousals, especially in the first half of the night when deep sleep is concentrated.
- Stress and anxiety increase the number of brief arousals during the night, creating more opportunities for the brain to get stuck between sleep and waking.
- Irregular sleep schedules disrupt your circadian rhythm and can intensify deep sleep on nights when you finally get to bed, raising the risk of an episode.
Medications That Can Cause Sleepwalking
Certain prescription sleep medications are known to trigger sleepwalking and other complex sleep behaviors, including driving, cooking, and eating while asleep. The FDA added its strongest safety warning (a boxed warning) to three sedative-hypnotic drugs after reviewing cases of serious injuries and deaths linked to these behaviors. The medications are zolpidem (sold as Ambien), eszopiclone (Lunesta), and zaleplon (Sonata). Of the cases the FDA reviewed, the vast majority involved zolpidem.
These episodes can happen even at recommended doses and even without alcohol. However, combining these sleep medications with alcohol, anti-anxiety drugs, opioids, or other sedating substances raises the risk substantially. If you’ve ever sleepwalked before, your doctor should know before prescribing any of these medications.
Sleep Apnea as a Hidden Cause
Obstructive sleep apnea, a condition where the airway repeatedly collapses during sleep, is an underrecognized trigger for sleepwalking. Each time the airway closes, oxygen levels drop and the brain is forced into a brief arousal to restore breathing. These arousals can be incomplete, pushing the brain into that half-asleep, half-awake state that produces sleepwalking. In documented cases, treating the sleep apnea with a CPAP machine eliminated the sleepwalking entirely.
This connection matters because many adults who start sleepwalking later in life, or whose childhood sleepwalking returns, may actually have an undiagnosed breathing disorder driving the episodes. Snoring, gasping during sleep, and daytime fatigue alongside sleepwalking are signs worth investigating.
Why It Peaks in Childhood
Children sleepwalk far more often than adults. The overall prevalence across childhood (ages 2.5 to 13) is about 29%, with the peak hitting around 13% between ages 10 and 13. The current rate in adults drops to about 1.5%. Children spend a much larger proportion of their sleep in deep slow-wave sleep compared to adults, which gives them more time in the vulnerable sleep stage. As the brain matures and deep sleep naturally decreases through adolescence, most children outgrow their episodes.
The lifetime prevalence of sleepwalking across all ages is about 7%, meaning roughly one in 14 people will experience at least one episode. For most, episodes are infrequent and harmless. But for a smaller group, sleepwalking persists into adulthood or begins later in life, often driven by one of the triggers or medical conditions described above.
What an Episode Looks and Feels Like
A sleepwalking episode typically begins with the person sitting up in bed, then standing and walking with open but glassy eyes. Their face is blank, and they’re largely unresponsive to people around them. Some episodes are simple, lasting 30 seconds of confused wandering. Others involve surprisingly coordinated behavior: getting dressed, eating food, rearranging furniture, or even leaving the house. Trying to wake a sleepwalker is difficult, and if you do manage it, they’re usually confused and disoriented for several minutes.
The person almost never remembers the episode. At most, they might recall a single fragmentary image, not a full dream or narrative. This is fundamentally different from acting out a dream, which happens during REM sleep and involves a separate condition entirely. Sleepwalking involves no dream storyline because the dreaming parts of the brain aren’t active.