"We identified a disorder, what is the rapid eye movement sleep behavior disorder, or RBD, mainly affecting men 50 or older who were acting out violent dreams involving unfamiliar people or animals," said Schenck. "After we followed these men along for a decade or longer, we realized that at least two thirds of these men developed Parkinson's disease, which is a traditional neurologic disorder involving tremor and rigidity."
Such potential complications are among the reasons Doyle finally signed up for a sleep study at the Minnesota Regional Sleep Disorders Center. He was wired up so that researchers could monitor his brain and body.
Doyle's wife, Cheryl, said that her husband has been walking, talking and occasionally raging at her in his sleep throughout their eight-year marriage.
"He'd bolt up right out of bed, would scream, yell, like a night terror," said Cheryl. "Sometimes he would scream that the house was on fire. Sometimes it was just nonsense -- there were dogs in the house and we needed to get the dogs out. The only time I would probably run after him is if I'd hear the front door open or the garage door open."
Doyle said the episodes were happening "three, four, sometimes five, six times a night."
One of his recent night episodes involved the movie "Cape Fear." In the film, Robert De Niro stars as an ex-con who stalks the family of a lawyer played by Nick Nolte.
"There's a scene where the family is on the boat in the river and the family is trying to escape Robert De Niro and all jumped into the river, and I dreamt that I was on that boat and I got up out of bed, I got a running start and dove into our living room," said Doyle. "Basically just got up and went back to bed and wasn't until a couple hours later wondering why the bed was wet and I realized when I turned on the light that my knees were bleeding from having scraped my knees."
"He's not himself at night when he has these episodes," said Cheryl. "He's a totally different person. "
In his night personality, Doyle has hurt himself and acted belligerently -- though never violently -- with his wife. But sleep disorders have played prominent roles in crime.
Ten years ago Scott Falater, a devout and devoted family man with no criminal past, stabbed his wife and held her under their pool. He claimed he was sleepwalking. A jury convicted him of murder.
But in 1987, Canadian Kenneth Parks was found not guilty of killing his mother-in-law, because experts testified he was asleep.
"Someone with a parasomnia can commit an act of murder and have no idea what he or she is doing in the process, so on that basis, yes they should be considered innocent," Schenck said.
During his sleep study, Doyle was monitored overnight and through a series of naps totaling nearly 24 hours. In the morning, Dr. Schenk and Dr. Mark Mahowald -- a neurologist -- went over the results.
"His REM sleep did appear normal," said Mahowald.
Doyle and Cheryl got some good news: The sleepwalking did not appear to be the more serious REM behavioral disorder, (RBD) the red flag for Parkinson's disease.
"The bottom line is that you have sleep apnea that is superimposed on your sleep walking," explained Schenck. "You did have one episode of confusional arousal with mumbling out of slow wave sleep which is very consistent with the sleep walking history. But you had mild to moderate obstructive sleep apnea, 25 episodes an hour."