People have driven cars, sometimes for miles, while technically asleep. It sounds impossible, but documented clinical cases and sleep-lab recordings confirm that sleepwalking can include behaviors as complex as operating a vehicle. The phenomenon makes more sense once you understand that during a sleepwalking episode, the brain is not fully asleep or fully awake. Some regions activate enough to support coordinated movement and even rudimentary navigation, while others, particularly those responsible for judgment, memory formation, and full conscious awareness, remain in deep sleep. That partial waking state is why a sleepwalker can turn a key, shift gears, and steer down a road without any recollection of doing so.
What the Clinical Record Shows
One of the best-known published cases involves a 43-year-old man with childhood-onset sleepwalking who drove a long distance during a presumed somnambulistic episode, in addition to a history of violent nocturnal behaviors including running, throwing punches, and wielding knives.1Sleep. A Polysomnographically Documented Case of Adult Somnambulism With Long-Distance Automobile Driving and Frequent Nocturnal Violence: Parasomnia With Continuing Danger as a Noninsane Automatism? That case, documented with polysomnography, demonstrated that sleepwalking episodes can involve sustained, goal-directed actions far beyond shuffling around a bedroom. A broader clinical review notes that driving motor vehicles, suspected suicide, and even homicide have all been described during adult sleepwalking episodes.2Sleep Science and Practice. Disorders of Arousal in adults: new diagnostic tools for clinical practice
These cases are not common, but they are not isolated curiosities, either. The phenomenon occurs on a spectrum. Most sleepwalking episodes are brief and mundane: sitting up, walking to the bathroom, mumbling. On the far end of that spectrum sit behaviors like cooking meals, leaving the house, and yes, driving. What unites them is that the person performing these acts is not consciously directing them and will typically have no memory of them afterward.
How Part of the Brain Stays Asleep While Part Wakes Up
The key concept is that sleep and wakefulness are not always all-or-nothing states. During a sleepwalking episode, motor regions of the brain can activate while frontal areas responsible for planning, self-awareness, and decision-making remain dormant. EEG studies of sleepwalkers show that in the seconds before an episode begins, there is a spike in fast brain-wave activity concentrated in the cingulate motor area, a region involved in initiating movement.3Clinical Neurophysiology. Sleepwalking episodes are preceded by arousal-related activation in the cingulate motor area: EEG current density imaging
High-density EEG research has filled in more detail. Sleepwalkers show a persistent drop in slow-wave power over the motor and sensory regions of the brain compared to normal sleepers, even during stable deep sleep when no episode is happening. The affected areas include the cingulate cortex, motor cortex, and sensory-association regions.4Sleep. Scalp and Source Power Topography in Sleepwalking and Sleep Terrors: A High-Density EEG Study In other words, in people prone to sleepwalking, certain brain regions never fully settle into deep sleep the way they should. When an arousal trigger hits, those regions are primed to wake up and start generating movement while the rest of the brain sleeps on.
Recent research confirms this pattern holds across ages. A 2025 study examining both children and adults with disorders of arousal found that episodes emerge from a globally less activated cortical state, with surges of activity in premotor, orbitofrontal, and anterior cingulate regions just before an episode starts. After onset, there is widespread activation in sensorimotor and parietal areas while the frontal lobes maintain a deep-sleep signature.5bioRxiv. Shared local brain dynamics in pediatric and adult NREM parasomnias This is what researchers call local sleep-wake dissociation: sleep and wakefulness coexisting in different parts of the same brain at the same time.
Why Sleepwalkers Can Navigate Without Being Conscious
If frontal decision-making areas are asleep, how does someone manage anything as complex as driving? Part of the answer lies in how deeply practiced motor skills are stored in the brain. Driving, for experienced drivers, is heavily automated. You do not consciously think about pressing the brake or turning the wheel for each action; those sequences are encoded in motor and subcortical circuits that can run with minimal conscious oversight. A sleepwalker’s brain appears to access those automated routines.
Experimental evidence supports this. When researchers tested clinically diagnosed sleepwalkers on a walking task using motion capture and virtual reality, they found something striking: under normal conditions, sleepwalkers and controls performed similarly. But when a demanding cognitive task was added on top, the control participants slowed down significantly while sleepwalkers maintained their walking speed and actually showed better awareness of deviations in their walking trajectory than controls did under the same load.6Current Biology. Distinct locomotor control and awareness in awake sleepwalkers The researchers concluded that sleepwalkers have a stronger dissociation between locomotor control and conscious awareness, meaning their motor systems run more independently of the thinking brain.
There is even evidence that sleepwalkers can replay recently learned motor sequences during an episode. In one study, a patient who had been trained on a specific hand-and-arm motor task during the day was observed during slow-wave sleep re-enacting accurate fragments of that task, pressing down with her hands as though operating invisible pads in the correct trained sequence.7PLOS ONE. Evidence for the Re-Enactment of a Recently Learned Behavior during Sleepwalking This suggests the sleeping brain can access procedural memory, the kind that stores “how to do things,” including how to drive.
Why Sleepwalkers Almost Never Remember What They Did
The amnesia that follows a sleepwalking episode is one of its most consistent features. A person who drove several miles asleep will typically wake up with no memory of the trip. The explanation appears to involve the hippocampus, the brain structure critical for encoding new conscious memories. During sleepwalking episodes, the hippocampus retains sleep-like activity markers even while motor regions are activated, which likely prevents the formation of retrievable memories.8Current Biology. Sleepwalking
This is different from simply forgetting. The memory was never properly formed in the first place. Some sleepwalkers report vague fragments of dream-like imagery from an episode, but coherent narrative recall is extremely rare. The amnesia also creates an obvious problem: if you have no idea you drove while asleep, you have no way to take precautions unless someone else witnesses the behavior or you notice telltale signs like unexplained mileage, a car parked in an unfamiliar position, or arriving at work in your pajamas.
Sleep Medications and “Sleep Driving”
Not all sleep driving comes from spontaneous sleepwalking. A major cluster of reported cases involves sedative-hypnotic medications, particularly zolpidem (Ambien) and similar drugs. These cases attracted enough FDA attention to prompt a black-box warning. A clinical case series documented that sleep driving and other complex automatisms can occur after zolpidem ingestion, sometimes with the person having no memory of taking additional doses of the drug during the night.9PubMed Central. Zolpidem Ingestion, Automatisms, and Sleep Driving: A Clinical and Legal Case Series
A review of the broader literature found that zolpidem and zopiclone in particular have been associated with the majority of reported impaired-driving cases linked to sleep medications, with numerous studies finding these drugs in driving-under-the-influence-related police stops, arrests, and accidents.10Sleep Medicine Reviews. Sleep driving: Sleepwalking variant or misuse of z-drugs? Whether drug-induced sleep driving is the same phenomenon as spontaneous sleepwalking or a distinct pharmacological effect remains debated. The brain state may overlap, since both involve partial arousal from deep sleep with motor activation and frontal suppression, but the trigger is different. In drug-induced cases, the medication itself destabilizes the boundary between sleep and wakefulness.
Alcohol compounds the risk. Many documented cases of sleep driving involve someone who took a sleep medication after also drinking. The combination lowers the threshold for complex automatisms. If you take a sleep medication, the standard advice to go to bed immediately and allow a full night’s sleep before driving exists specifically because of these cases.
What Makes Sleepwalking Episodes More Likely
Sleepwalking arises from deep non-REM sleep, typically in the first third of the night when slow-wave sleep is most concentrated. Several factors increase the likelihood of episodes, and understanding them matters because reducing triggers is the most practical way to prevent dangerous behaviors like sleep driving.
Sleep deprivation is the most reliably documented trigger. In a controlled study of 40 diagnosed sleepwalkers, recovery sleep after a period of sleep deprivation nearly doubled the proportion of patients who experienced an episode (from half at baseline to nine in ten during recovery sleep) and tripled the total number of recorded episodes. Sleep deprivation also made the episodes more complex.11PubMed. Polysomnographic diagnosis of sleepwalking: effects of sleep deprivation This is one reason sleepwalking episodes sometimes cluster during periods of stress, shift work, or travel, all of which disrupt sleep patterns.
Other common precipitants include fever, a full bladder, noise, and sleeping in unfamiliar environments. Sleep-disordered breathing is a particularly important one. Research on chronic adult sleepwalkers found that many had underlying obstructive sleep apnea, and when their breathing disorder was treated, the sleepwalking resolved. Patients treated with continuous positive airway pressure (CPAP) had complete control of their sleepwalking at every stage of follow-up, while those who did not comply with CPAP continued sleepwalking.12PubMed. Adult chronic sleepwalking and its treatment based on polysomnography The logic is straightforward: each breathing disruption produces a brief arousal from deep sleep, and in a person predisposed to sleepwalking, those arousals can trigger episodes.
Genetics and Who Is Predisposed
Sleepwalking runs strongly in families. A meta-analysis covering over 100,000 participants estimated the lifetime prevalence of sleepwalking at about 7%, with the current rate in adults around 1.5%.13PubMed Central. Prevalence of Sleepwalking: A Systematic Review and Meta-Analysis A case-control study found that over half of adult sleepwalkers reported a family history of sleepwalking, and roughly a quarter had daily episodes.14SLEEP. Functional Impairment in Adult Sleepwalkers: A Case-Control Study
Twin studies put numbers on the genetic component. A population-based twin study found that genetic influences accounted for roughly 57 to 80% of the variation in sleepwalking susceptibility, depending on sex and whether the sleepwalking occurred in childhood or adulthood.15PubMed. Prevalence and genetics of sleepwalking: a population-based twin study In one large family, sleepwalking was inherited in a dominant pattern and was linked to a region on chromosome 20.16PubMed Central. Novel genetic findings in an extended family pedigree with sleepwalking
There is also an immune-genetics angle. A study of sleepwalkers found that a specific immune-system gene variant (DQB1*0501) was about three and a half times more common in sleepwalkers than in controls. Further analysis pointed to a particular amino acid in the DQB1 gene that was preferentially transmitted in families with sleepwalking, connecting sleepwalking to the same immune-gene region implicated in narcolepsy and REM sleep behavior disorder.17Molecular Psychiatry. HLA and genetic susceptibility to sleepwalking Nobody fully understands why immune-system genes influence sleep disorders, but the association is now well established across multiple parasomnias.
Sleepwalking Versus REM Sleep Behavior Disorder
Not every dramatic behavior during sleep is sleepwalking. REM sleep behavior disorder (RBD) is a different condition where people physically act out their dreams during REM sleep, typically later in the night. RBD tends to show up in older adults and is associated with neurodegenerative conditions, while sleepwalking usually begins in childhood and arises from deep non-REM sleep. The distinction matters because the two have different risk profiles, different trajectories, and different treatments.
However, the boundary between the two is not always crisp. Research comparing sleepwalkers to people with RBD found that sleepwalkers scored higher on RBD screening scales and showed some loss of normal muscle control during REM sleep, though they did not display the complex REM behaviors characteristic of full RBD. Likewise, patients with RBD had mildly elevated scores on a sleepwalking severity scale but did not actually produce the deep-sleep arousals typical of sleepwalking.18PubMed. Is there a common motor dysregulation in sleepwalking and REM sleep behaviour disorder? Some researchers think the two conditions may share an underlying vulnerability in the brain circuits that normally keep the body still during sleep, even though they manifest during different sleep stages.
The Forensic Problem
Sleep driving raises an uncomfortable legal question: can someone be held responsible for actions they performed unconsciously? Courts in multiple countries have dealt with cases where defendants claimed their criminal behavior occurred during a sleepwalking episode. The defense is not new; successful sleepwalking defenses date back well over a century. But establishing whether someone was genuinely sleepwalking at the time of an alleged crime is extremely difficult after the fact.
Forensic sleep experts typically look for a constellation of supporting evidence: a documented personal or family history of sleepwalking, circumstances consistent with a known trigger (sleep deprivation, medication, alcohol), behavior during the event that matches known features of sleepwalking (no apparent motive, confusion upon waking, amnesia for the event), and polysomnographic evidence that the individual is capable of sleepwalking.19PubMed Central. Defending sleepwalkers with science and an illustrative case Even with all of that, the potential for malingering makes these cases contentious. Specific diagnostic criteria have been proposed to help distinguish genuine parasomnia defenses from fraudulent ones.20PubMed Central. While You Were Sleepwalking: Science and Neurobiology of Sleep Disorders & the Enigma of Legal Responsibility of Violence During Parasomnia
The challenge is compounded in sleep-driving cases where medications were involved. If someone took zolpidem, got behind the wheel in an amnestic state, and caused an accident, the question of whether they are culpable often hinges on whether they were warned about the risk and whether they combined the drug with alcohol. Jurisdictions vary considerably in how they handle these cases.
Reducing the Risk of Dangerous Episodes
For people with a known history of sleepwalking, prevention focuses on reducing triggers and managing underlying conditions. Maintaining a consistent sleep schedule and avoiding sleep deprivation is the single most evidence-based behavioral intervention, given how reliably sleep loss provokes episodes. Screening for and treating sleep-disordered breathing is critical in adult sleepwalkers, since treating the breathing problem alone can eliminate sleepwalking entirely in many cases.
Environmental safety measures are standard clinical recommendations: locking doors and windows, keeping car keys out of reach, sleeping on a ground floor when possible, and removing potentially dangerous objects from the bedroom. For people who sleep-drive, putting the car keys in a locked box requiring a combination or a step that a sleeping brain is unlikely to manage is a practical intervention that sleep clinicians frequently suggest.
Medications like low-dose clonazepam are sometimes prescribed for severe cases, though the evidence for their long-term efficacy in sleepwalking is thin, and one study noted that patients treated with benzodiazepines alone tended to drop out of follow-up and report persistence of sleepwalking.12PubMed. Adult chronic sleepwalking and its treatment based on polysomnography The most robust treatment outcomes in the literature come from addressing comorbid sleep disorders rather than trying to suppress sleepwalking directly. If someone’s sleepwalking is being triggered by dozens of micro-arousals from apnea each night, fixing the apnea removes the trigger.
How Common Is Sleep Driving Specifically
Nobody knows the true prevalence of sleep driving, and there is a good reason for that: the person doing it is usually amnestic, and unless they crash, get pulled over, or are seen by someone else, the event goes undetected. Population-level data on sleepwalking in general show that roughly 1.5% of adults have sleepwalked in the past year, but only a fraction of those episodes involve anything as complex as driving.13PubMed Central. Prevalence of Sleepwalking: A Systematic Review and Meta-Analysis Studies of adult sleepwalkers find that about 58% have engaged in violent sleep-related behaviors and 17% have sustained injuries requiring medical care, but these figures encompass all dangerous behaviors, not just driving.14SLEEP. Functional Impairment in Adult Sleepwalkers: A Case-Control Study
The drug-induced cases are better captured because they tend to result in police encounters or emergency-room visits. But even those likely represent the tip of the iceberg, since someone who drives a short distance and returns home safely would have no way of knowing it happened. The overall picture is that sleep driving is rare in absolute terms but genuinely occurs, and for the individual affected, the consequences can be catastrophic. It is not a myth, not an urban legend, and not something that happens only in movies. The neuroscience explains how it is possible, the clinical literature proves it happens, and the forensic record shows that society is still figuring out what to do about it.