It could be a scene from a horror movie called "Night of the Hungry Zombies." A sleepwalker enters the kitchen, grabs anything within reach -- cookies, crackers, even a dish scouring pad -- and chows down, sometimes taking food back to bed.
Only this is a real life nightmare for 43-year-old Anna Ryan, and one million other Americans. And it has nothing at all to do with hunger.
"There's a compulsion to eat. But it's not a hunger-driven behavior," said Dr. Carlos Schenck, a psychiatrist and an expert in sleep research.
He was one of the first to complete a major study on Sleep Related Eating Disorder (SRED), after spending the past 20 years trying to understand it.
"We've had patients consume cat food sandwiches. They've put coffee grounds, Coca-Cola, and eggshells in a blender and consume it. They eat Elmer's Glue. They chew on chunks of frozen pizza and then try to swallow it. They're like sleeping zombies, just walking around headless. Except that they have a mouth to feed."
Ryan is what doctors call a parasomniac, someone with a sleep disorder that leads to an abnormal event during sleep. These odd behaviors can range from walking to having sex, known as sexsomnia, to acts of aggression and violence, all while asleep.
What may trigger the unusual acts of parasomniacs like Ryan is the shutdown of the brain's frontal lobe during sleep, Schenck said. The frontal lobe is the seat of judgment. Brain scan studies and other research shows that when people doze, their frontal lobe switches off. At the same time, the remainder of the brain may become more active and direct the sleep eater to immediately seek food.
"They can get up, they see their environment," Schenck said. "They know where the kitchen is. But they have no judgment, no inhibition. And that's the problem."
Sleep Eater Completely Unaware of Midnight Munching
Ryan says she has been a sleepwalker since age 12 and she now believes her sleep eating problem started more than 10 years ago. She never remembers a thing about her nightly forays to the kitchen, which she has learned can occur up to four times a night. She first began suspecting she had a problem when she awoke to strange clues in her home.
"There was food missing. Then I would find wrappers around the house," said Ryan, who lives near Kansas City. "Sometimes I'd find things out of place. I knew I put something somewhere that night, and then the next morning it wasn't there. Diets would work real well, and then all of a sudden, they wouldn't work at all."
Unaware that she had been consuming thousands of calories in her overnight kitchen raids, Ryan was frustrated that no matter how strictly she stuck to her diet by day her fight against weight gain seemed to be a losing battle.
"It's just unbelievable that I could that I could do those things and not remember them," Ryan told ABC News. "There's me and then there's this other person who comes at night. I do things that I don't do during the day, so it's like it's another person."
To help diagnose patients who suffer from sleep eating, doctors often have cameras set up to tape their behavior in sleep labs. The results are typically jarring, not necessarily to the doctors but to the patients themselves.
"Patients who have a sleep behavior disorder such as sleep eating, when they see the tape of themselves, they truly are shocked, saying, 'My God. I didn't realize I was capable of doing this,'" said Schenk.
Ryan recently watched surveillance footage of herself arising from bed still asleep, walking to the kitchen counter and then picking up pieces of food. She then walked back to the bedroom, got onto the bed and started to eat.
"It's very slovenly," said Ryan as she watched the tape. "Look at that. Lying down. Chewing."
Ryan said seeing herself sleep eating was "scary. It's unbelievable. It's sickening."
Dangers of Sleep Eating
What's even more mind boggling is the menu Ryan has selected, which doesn't always include edible items.
"My nephews caught me in the middle of the night eating an SOS pad," she said, referring to the steel wool dish detergent pad. "It doesn't matter what you're eating."
As disturbing as the behavior is, it's typical of a parasomniac and can put them -- and their loved ones -- in danger.
"People have put napkins in a toaster and started fires," Schenk said. "They've cut their fingers chopping food. We're talking about major risk of injury during the night from the sleep eating and the associated sleep walking."
For Ryan, the hazards have included waking up covered in blood, only to find her front tooth missing, and falling down a flight of stairs, during which she wrenched her knee to the point that she needed reconstructive surgery for her anterior cruciate ligament (ACL).
"We've tried restraints, against medical advice," said Ryan, who lives with her husband Kenny. "They don't work. I end up hurting myself."
Beyond the trauma she's suffered, Ryan's sleep eating has caused her to struggle with her weight and face potentially life-threatening issues such as hypertension and high cholesterol.
Her struggle to get her sleep eating under control has led her to a sleep specialist, who has prescribed a combination of drugs, including anti-seizure medications. So far, they have only been occasionally successful in reducing her episodes of sleep eating.
"I'm going to do what it takes to get better," Ryan said. "I really don't know what to expect. I just know I'm going to live every day the best that I can."
While many questions about the connection between sleep and eating remain unanswered, Schenk said it's clear that sleep eating has absolutely nothing to do with a person's conscious control of their diet.
"It's not willpower. It's not a psychological problem," Schenk said. "It's a major physiological force coming from within your brain and body to eat at night so inappropriately."
Meanwhile, Ryan said she is speaking about her problem to get out the word that overweight sleep eaters are not just coming up with a convenient excuse for the extra pounds.
Eliminating the Shame of Sleep Eating
"People perceive it as a willpower problem. It's not," Ryan said. There are a lot of people out there who suffer from this. Putting it out there takes the shame away."