The sleeping brain, left to its own devices, rules an eccentric, sensual and sometimes violent landscape.
When she woke up to find her husband on top of her in the middle of the night, Vanessa Otts tried waking him, but she says he didn't wake up.
"My clothes were pretty much off and his clothes were off, and all of a sudden, he just rolls back over and goes back to sleep," Vanessa says.
When Vanessa told Tyson that he tried having sex with her during the night, he denied doing anything to her. "I think I would remember almost having sex with you," he says. " There's no way that that happened."
The Otts have a strange but real problem. In the five years of their marriage, Tyson routinely initiates sex with his wife when he is sound asleep.
Doctors have given this act of sex while sleeping a medical-sounding name: sexsomnia.
Nancy Foldvary, the director of the Sleep Disorders Center at the Cleveland Clinic, calls the problem "real."
Foldvary says she's primarily seen men with this disorder, men who have come to her because their bed partners were complaining. "He just gets really aggressive, I guess you could say. He's actually become more physical, like holding me down, or taking my shirt off, or, you know, forcefully kissing me," Vanessa says.
Tyson says the scary part is that he has no recollection of his actions during the night.
So is it possible for someone to rape an individual and claim he was sleeping when he did it?
Foldvary says it's possible that a person "could have sex without any memory for it, during a sleep state."
In cases around the world people have used sexsomnia -- sometimes successfully -- as a legal defense for rape.
Mike Mangan is a research psychologist at the University of New Hampshire and acknowledges people use this defense.
"People walk in their sleep. They talk in their sleep. People do all kinds of crazy things in their sleep," he says. "And it just hasn't entered the popular mind that sexual behavior is just another type of behavior that occurs in sleep."
As for the underlying causes of sexsomnia, researchers have begun focusing on what amounts to a "mind-body disconnect," a disconnect between our primal urge for sex and the cortex of the brain that controls rationality and judgment.
"Basically, what you have is a sexually motivated body and a cortex that has switched off. When that's switched off, you have a sexually active body that is having its way," says Mangan.
Though sexsomnia is clearly unusual, researchers say the actual number of cases is underreported, and it shows up in both men and women. The cases, however, are rarely caught on tape.
Lori Norman told what happened to her one night while sleeping with her husband, Bob. "I woke up with him pounding the pillow right beside my face. I mean within inches of my face."
Lori and Bob have become accidental combatants in a nocturnal prizefight. Repeatedly during their nine-year marriage, a sleep disorder has caused Bob to unwittingly assault his wife.
"We were sound asleep, and he takes his two hands with his fist together and pounds the back of my neck. And I just screamed, and I threw my hands up over my head, and I grabbed his hands, as they were coming down again," Lori says.
Keep in mind that in every other way, the Normans say they're a loving, happy couple. When her husband is not sleeping, Lori says, "He just exudes this peacefulness."
After all, Bob has been meditating for 35 years, so he says he considers himself healthy and peaceful.
But when night hits, sometimes those peaceful, daytime thoughts turn violent.
"I'm watching a flock of ducks on the water. They're just swimming around there. And at some point they started coming toward me." That's when Bob says he felt he was in danger. "They [the ducks] were going to attack me."
The battle in his brain is also being played out in the bed.
"I was absolutely sound asleep and he suddenly kicked me. I mean really hard," Lori says.
Bob was eventually diagnosed with REM Behavior Disorder or RBD -- a condition that occurs in the REM stage of sleep.
"In REM sleep the brain is very active. We dream. But otherwise the skeletal muscles, the muscles of the arms and legs are paralyzed and that's the normal state of REM. It's almost a protective effect to be paralyzed so that we cannot move during that state," Foldvary says.
But in people with Bob's sleep disorder -- the natural mechanism that causes paralysis during sleep fails.
Foldvary explains that people like Bob are "acting" on a dream. "They're not waking up. They thrash around. They may consider the wife an enemy."
Researchers have begun linking the odd behaviors of RBD to other, even more serious neurodegenerative disorders, like Parkinson's disease.
"What is clearly coming out is that REM behavior disorder appears eight to 10 to 15 years before patients develop Parkinson's disease," Foldvary says.
Foldvary says violent sleep can "absolutely" be a precursor to other disorders.
This is a daunting thought for Bob. "It's extremely scary to think that five years from now, or 10 years from now, I'm going to be progressing through stages of Parkinson's disease," he says.
In the meantime, Bob has tried medications that help most RBD sufferers and together, he and Lori have tried a host of practical ideas to keep Bob sleeping and Lori safe. They put a row of pillows between them. They moved from a double bed to a queen-size bed and then to twin beds.
But none of these remedies stopped the RBD completely.
"I kicked her right across the gap between us," Bob says.
So for now, Bob keeps on with his meditation sessions, contemplating the night when he and Lori no longer have to be such strange bedfellows.
"Every single night we say to each other, 'Have a good night, dear.' And it's almost a joke because, we don't," Lori says. "But you know, at least you always hope."