Mind & Brain See Inside Are Sleepwalking Killers Conscious? Some people commit violent acts while asleep. In seeking to understand their brain states, scientists and physicians are investigating the murky borders of consciousness By Francesca Siclari, Giulio Tononi and Claudio Bassetti SAMUEL BRADLEY Getty Images On the morning of May 24, 1987, sometime after 1:30 A.M., a 23-year-old Canadian named Kenneth Parks drove 14 miles to his in-laws' home, strangled his father-in-law to the point of unconsciousness, and beat and stabbed his mother-in-law to death. A year later he was acquitted of both assault and murder. After a careful investigation, specialists reached the astonishing conclusion that Parks had been sleepwalking—and sleep driving and sleep attacking—during the incident. This story inspired a 1997 made-for-television movie, The Sleepwalker Killing, starring Hilary Swank as Parks's wife. Although such extreme cases are rare, unintended acts of violence during sleep are quite common among those with sleep disorders. In a 1995 study of 64 sleep clinic patients suffering from sleepwalking or sleep terrors, more than half exhibited harmful behavior during sleep. An analysis at a different clinic that same year concluded that 70 percent of their 41 sleepwalking patients acted in a potentially injurious way. This is only a preview. Get the rest of this article now! Select an option below: Buy Digital Issue Customer Sign In *You must have purchased this issue or have a qualifying subscription to access this content It has been identified that the institution you are trying to access this article from has institutional site license access to Scientific American on nature.com. Click here to access this article in its entirety through site license access. ADVERTISEMENT Scientific American is a trademark of Scientific American, Inc., used with permission © 2013 Scientific American, a Division of Nature America, Inc. All Rights Reserved.