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joi, 23 august 2012

Somnambulant Savagery: When Sleep Turns Violent

More than 25 years later details of the attack are still shocking: Sometime after 2 A.M. one Sunday morning in May 1987, Kenneth James Parks, then 23, left his house in a Toronto suburb and drove 23 kilometers to the apartment of his wife's parents. He got out of the car, pulled a tire iron out of the trunk and let himself into the older couple's home with a key they had given him. 

Once inside, he struggled with and choked his father-in-law, Dennis Woods, until the older man fell unconscious and then struggled with and beat his mother-in-law, Barbara Ann Woods, stabbing her to death with a knife from her kitchen.

Parks then got back into his car, drove to a nearby police station and announced to the startled officers on duty, "I think I have killed some people." For several hours before the Toronto man left his home, however, and throughout the course of the attack, Parks was asleep and therefore not criminally responsible for his actions, according to five doctors and the defense lawyer at his 1988trial for the murder of Barbara Ann and the attempted murder of Dennis. After deliberating for nine hours, the jury agreed and Parks was set free. Although prosecutors at the time considered the defense "ludicrous" and appealed the judge's decision to allow the jury to consider a sleepwalking defense, the Canadian Supreme court upheld the original ruling in 1992.

Even the sleep specialist who was first brought in as a consultant on the case was initially skeptical that a sleepwalker could have undertaken such a series of complex behaviors—including safely driving through three traffic lights and portions of an express highway—before attacking anyone. After all, most people who strike out in their sleep usually injure themselves or the person sleeping next to them—not someone 23 kilometers away. But further examination showed that the tragedy was not, as it had first seemed, a clear-cut case of murder.

For starters, Parks was an unusually deep sleeper (as verified by laboratory instruments). He had frequently talked in his sleep as a child, had sometimes sleepwalked as well and was a severe bed-wetter until 11 or 12 years of age. A 1974 study of 50 adults who acted violently while sleeping found that many of the subjects wet their beds or sleepwalked as children. One night, one of Parks's brothers actually had to grab him by the leg as he was about to walk through a window. Sleepwalking, sleep-talking and bed-wetting were also common in other members of his family across three generations.

While sleepwalking is a fairly routine occurrence among youngsters—happening in about 15 percent of children—it typically does not lead to attacks on other people. Indeed, sleepwalking children can usually be guided back to bed without any incident. They also are likely to outgrow the sleepwalking tendency.

Far fewer adults walk in their sleep. But unlike children, they are more likely to turn hostile or aggressive when others try to rouse them, as has been documented in several studies.

To be sure, some details of Parks's life did not put him in the best possible light: Almost a year before the attack, he developed a really bad gambling habit, which put a lot of stress on his marriage. He ended up embezzling $30,000 at work to try to cover his debts and keep them from his wife. Two months before the attack the theft was discovered and Parks was fired. He stopped gambling for a few weeks then started up again, twice forging his wife's signature to get more money. Three days before the attack, he attended his first Gamblers Anonymous meeting and decided to come clean to his in-laws, with whom he had been, by all accounts, very close. Two nights before the attack he couldn't sleep, thinking about what he would say to them.

The psychiatrists and other medical experts who examined Parks could find no evidence of brain disease or psychosis. He seemed genuinely devastated by what he had done. Measurements of his brain waves during sleep showed that he naturally cycled more often and more rapidly than most people from the deepest levels of sleep to wakefulness. He also felt no physical pain during his homicidal episode, in spite of the fact that several tendons in his hands were severed during the course of the attack (requiring surgical repair), until after he reached the police station.

Incredible as it seemed, the medical team concluded that sleepwalking was the one explanation that fit all the facts of the case. And indeed, as James Vlahos reports in the September 2012 issue of Scientific American, research over the past two decades since the Toronto tragedy supports the idea that the brain does not fall asleep all at once; and in some small number of individuals the timing with which various regions of the brain go offline becomes so disorganized that these people can walk, sleep, drive or cook entire meals without any awareness of what they are doing.

Why did Parks drive to his in-laws' home in his sleep rather than some other random address? Researchers believe that the part of his brain that wasn't asleep was just enacting what he had planned to do later that day. Why did Parks attack his in-laws so violently? Even the prosecution could not come up with a motive for the crime. Nor did it suggest that there was any advantage Parks might have gained because of it.

More than likely, sleep scientists think, Parks was not acting out a dream. The kind of sleepwalking he experienced occurs during a stage of sleep in which dreams are uncommon and consist mostly of fragmentary images. In addition, the part of the brain that tells us which actions are appropriate in a given situation (the prefrontal cortex), is inactive in this stage of sleep.

Instead, it appears that Dennis Woods found his son-in-law wandering about in the dark, tried to stop him and Parks responded as if his life were in danger. The part of his brain that could have told him otherwise was so exhausted by the previous night's insomnia and the stress of his gambling debts that it was, tragically, unavailable to inhibit his lethal actions.

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