A Stanford study published last month found that 3.6 percent of U.S. adults sleepwalk. That means that more than 8.4 million Americans could be wandering in the night unconscious of their actions. Some, like my brother who once woke up in the kitchen after chewing through a PowerBar wrapper, exhibit harmless behavior. But others may attempt to drive a car or engage in far more dangerous activities.
As reported in a recent Observations post, a subset of sleepwalkers, comprising about 2 percent of the general population in North America and Europe, may be at risk for one of three disorders associated with sleep violence, and related incidents have ranged from running and kicking to assault and even murder. Daisy Yuhas writes:
Because various disorders can underlie sleep violence, investigating incidents is understandably challenging. Michel Cramer Bornemann, [MD,] a sleep specialist at the Minnesota Regional Sleep Disorders Center, and his colleagues at the center’s Sleep Forensics Associates have handled more than 200 forensic cases related to sleep disorders, often at the request of law enforcement. Of these, only arousal disorders have been associated with criminal behavior during sleepwalking. He estimates that about a third of cases the forensics associates encounter involve sleep drugs, such as Ambien, which may increase the risk of experiencing an arousal disorder.
Ongoing research to better understand the brain states of those afflicted by such disorders is highlighted in a feature (subscription required) in the latest issue of Scientific American. The article also discusses symptoms of arousal disorders, wherein a person "operates in a mental state between wakefulness and sleep, carrying out complex behaviors with no evident conscious awareness." Other disorders associated with sleep violence include nocturnal frontal lobe epilepsy and rapid eye movement (REM) sleep behavior disorder.