By Shari Langemak
DIE WELT/Worldcrunch

BERLIN - The first thing Kenneth Parks remembers that night was his mother-in-law's mouth, twisted by fear. That and her frozen eyes. She was lying on the floor beneath him, dead. In disbelief, he slowly realized he was holding a blood-drenched kitchen knife.

As if in a trance, he dropped the knife and went to the police station. "I think I may have killed a couple of people," he told officers. He was right. During the night of May 23, 1987, Parks drove to the home of his parents-in-law, strangled his father-in-law and, with five stabs of the knife, killed his mother-in-law.

The problem is he can't remember any of it. What may read like a thriller is bitter reality for this Canadian man, whose only explanation is that he was sleepwalking. After five long years behind bars, the courts released him after recognizing he was not responsible for his actions.

If sleepwalking is a challenge for legal authorities, it's an even greater one for scientists who have been studying the phenomenon for centuries. It is all the more fascinating since – even after all these years – so little is known about it. Sleepwalking remains a puzzle, not least because it's so difficult to prove. It doesn't cause any measurable changes to blood, nerves or the brain, which is why most test methods, from blood samples to magnetic resonance tomography, are not particularly helpful.

Neurologists try to diagnose the condition by observing patients in sleep labs, where they film video footage and measure the electrical activity of the brain with electroencephalograms(EEG). But results are only middling, says Dr. Pascal Grosse, head of neurology at Berlin's Charité hospital. "Sleepwalking where the person actually gets up out of bed almost never takes place in a sleep lab," he says. "Even if you look at all the information available worldwide, you'll only find about 10 cases where they did."

Just why sleepwalkers should be lab-shy is also unknown, although being hooked up to EEG equipment may well have something to do with it. Even if they remain bed-bound, sleepwalkers can still be quite active. Often they experience what is known as "confusional arousal." This is when a person suddenly sits up, opens his or her eyes, and looks around in a seemingly disoriented way. This usually lasts about a minute. Amazingly, an EEG records no change when it happens: the devise continues to register deep sleep.

Business trip risks

Deep sleep phases of the sleep cycle are when the body recovers from the stresses of the day. In healthy adults, movement and deep sleep are mutually exclusive. Among children, however, roughly 15% walk in their sleep before the age of puberty – possibly because their nervous systems are not yet completely developed, according to Professor Geert Mayer, the chair of the German Sleep Society (DGSM).

Researchers working with psychiatrist Maurice Ohayon at Stanford University recently discovered that sleepwalking after the age of puberty is far more common than previously assumed. His study, published in Neurology, says that over the course of the past year 3% of U.S. citizens will have sleepwalked. And in many cases they have themselves to blame, according to the study.

As a result of things like too little sleep, stress and alcohol, the body's longing for deep sleep is so great that it goes into a kind of half-sleep in which the person is apparently engaged in activity but is not entirely conscious. The activity usually involves getting up to use the toilet or making a late-night snack. It sounds harmless enough, but it can nevertheless cause problems – as in the classic example when a hotel guest confuses the window for the bathroom door.

Sleepwalking is especially prevalent when people are on business trips, when things like unfamiliarity with the environment, lack of sleep, stress, and overconsumption of alcohol can be contributing factors. But based on the findings of his study, Ohayon says that in about a third of all cases, there is also a genetic predisposition to sleepwalking – something that recent genetic analysis experiments support.

Kenneth Parks's case is likely one of genetic predisposition: the fact that sleepwalking was frequent among his relatives played a major role not only in his diagnosis but also in his ultimate release from prison.

Professor Mayer says Parks's gruesome case is a rarity: most sleepwalkers are very peaceful and if there are any injuries, it's usually to themselves. Sleepwalkers, however, may get aggressive if they are ripped suddenly from their dream world. Be wary, in other words, if you plan to wake them up.

"If you wake up a sleepwalker, they mostly react defensively," says Professor Mayer. "So don't wake them up. Instead, just guide them gently back to bed." And that's about the only advice doctors have to offer at the moment – aside from making sure that potential sources of injury, particularly in the bedroom, are minimized.

Read the original article in German

Photo - Sebastian Fritzon