(ABC NEWS) -- After a five-day trial, a jury took just two hours to acquit a British Royal Air Force mechanic of raping a 15-year-old girl. His defense: sleepwalking.
Kenneth Ecott, 26, was found not guilty of rape earlier this month, despite admitting to having nonconsensual sex with a minor. Ecott insisted he suffered from a sleep disorder and had no memory of the incident.
Like walking, eating or driving in your sleep, sleep sex or "sexsomnia" is a rare, but real, phenomenon, experts told ABCNEWS.com.
Ecott, whose regular sleepwalking in the air force earned him the nickname Night Rider, said after an evening of heavy drinking at a birthday party, he passed out along with several other guest on an air mattress set up in his friend's living room.
His accuser testified to waking up at 3 a.m. with Ecott on top of her. She screamed and watched as he slowly walked naked out into the home's garden.
"I was drunk and went to sleep, then I woke up and my life was over. I was standing outside, completely naked, wondering what the hell I was doing there," Ecott testified.
"Everyone was asking, 'What have you done?' Sleepwalking is the only rational explanation for what I did," he said.
Sleep experts call any behavior not typically associated with sleep "parasomnia."
"Talking in your sleep is rare, walking rarer, eating very rare, and driving extremely rare," said Dr. Colin Shapiro, of Toronto Hospital's Sleep and Alertness Clinic.
"Sexual intercourse during sleep is probably more common than people realize. Any number of students in university have stories of going to the toilet, ending up in the wrong room, and touching up a stranger," he said.
Parasomnia is relatively common in children, but only 3 to 6 percent of adults continue to display such behaviors.
Shapiro has testified in several cases, including rape and murder trials, in which the accused claimed they had been sleeping at the time.
In 2005, he testified on behalf of Jan Luedecke, who claimed he passed out on a couch beside the woman who later accused him of rape, but he had no memory of having sex with her.
In both Ecott and Luedecke's cases, alcohol was involved, but, experts say, so were the sleepwalkers' genetics.
"Certain events will trigger episodes in people who have previously displayed parasomnia. Sleep deprivation, stress, and alcohol consumption can all trigger parasomnia, but only in people who are genetically predisposed ... We conducted tests, not only on Jan Luedecke, but on his family members as well. All showed evidence of parasomnia," Shapiro said.
Shapiro added that alcohol consumption raises questions about whether a person accused of rape was simply drunk or suffered from sexsomnia. Only from a study in a sleep center, in which the subject's brain waves are monitored by doctors, can experts conclude whether a person displays abnormal sleep patterns.
But legally, is a sleepwalker responsible for his or her actions?
Generally, no, said Stephen Morse, a professor of law and psychology at the University of Pennsylvania.
In the United States, as in Britain and Canada, the state must prove that someone was aware enough to knowingly commit a crime.
"If someone has Huntington's disease and has ticks, and reflexively hits someone in the face, that person cannot be held accountable, because the strike was the result of an unconscious reflex," said Morse.
"Sleepwalking is slightly different from such a reflex reaction. Sleepwalkers seem attuned to their environment, and are seemingly goal-directed, but they are not completely conscious."
Sleepwalking has been used as a criminal defense since the 19th century, Morse said.
In 1846, Albert Tirrell became the first American to be acquitted on a sleepwalking defense after he was accused of murdering a prostitute and burning down her brothel.
In 2001, a jury acquitted Adam Kieczykowski, a self-proclaimed sleepwalker, after he was charged with burgling 10 dorm rooms at the University of Massachusetts at Amherst.
But victims' rights organizations see sleepwalking, particularly in instances of rape, as merely an excuse, and not a legitimate defense.
"This is just another way men are let off the hook and not made responsible for crimes committed against women," said Daisy Kler, spokesperson for the Canadian Association of Sexual Assault Centers. "Sleepwalking is used as an excuse, like, 'I was drunk or I was high.'"
"Neither Ecott nor Luedecke denied having sex with these women. Ecott knew he had a problem, but didn't take precautions. He didn't lock himself in his room, or avoid sleeping in a group of young girls."
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