Some of us don't know we are sleepwalkers, says Dr. Ana Krieger, director of the NYU Sleep Disorders Center.
Scott Falater of Phoenix was sentenced to life in prison in 1999 for fatally stabbing his wife. His defense was that he had been sleepwalking.
A Florida man was just acquitted of lewd conduct charges. His defense? He didn't mean to touch a young girl; he was sleepwalking. While very difficult to prove, the man's defense is at least plausible, according to Dr. Ana Krieger, director of the NYU Sleep Disorders Center and an expert in "parasomnia."
"It is well known that some patients with sleepwalking have very complex behaviors at night. They have been found to be driving, eating, preparing meals," Krieger says. "We've seen people that say they wrote checks. They may not have necessarily made sense, but they did write and they signed."
Most of us miss out on sleep, Krieger says, but only 1 percent to 2 percent of people suffer from "parasomnia," or actions while sleepwalking. She says medications can exacerbate sleepwalking but don't cause it. Other factors include anxiety, sleep deprivation and high fevers.
The disorder is very difficult to stop, Krieger says. She and her colleagues identify aggravating factors, such as conditions that lead to interrupted sleep and medications.
What is actually going on in the brain? Krieger says sleepwalkers aren't dreaming; they are in a non-dream stage of sleep. She says that when someone is sleepwalking, processes that are going on in the brain manifest themselves in actions, behaviors and words.
"It has a genetic trait," Krieger says. "If you have a relative that has sleepwalking, you probably have a higher tendency of having it."
Of two myths about sleepwalkers, she says one is actually true.
Myth: Don't ever wake up someone who is sleepwalking. Verdict: True. "The major reason is because they're very confused, so if you wake them up, they may even act out aggressively," Krieger says. "In their minds, they're asleep. ... Try to safely guide them back to bed."
Myth: Sleepwalking behavior reflects a person's true character. Verdict: False. Krieger says some conduct is impulsive, but other sleepwalkers are totally methodical. "Some people can prepare a whole meal, while others can go and eat their plants. It's very hard to predict who is going to behave in which way," she says.
So, can it be proven whether a suspect was sleepwalking while committing a crime? Krieger suggests that it is almost impossible to say for sure. "You don't really know what happened in that particular incident," she says. "There is no way of knowing, because you're not monitoring the person during that incident."