The last REM period of the night comes six to seven hours later and it's "very long, very vivid, lots of color, lots of drama and lots of emotion," said Cartwright. "You go from a short preview of the coming attraction to a biggie and it goes from what is currently on your mind to long-term memories."
But the most heinous crimes tend to occur in non-REM parasomnias.
Instead of responding to dream narratives, these sleepwalkers do something peculiar, like go into the kitchen and make crazy food combinations that they would never eat when awake, like a "cold bacon and chocolate bar sandwich," according to Cartwright, "or they wander off in the car and crash it up."
Most violent sleepwalkers are men, but Cartwright treated one woman who killed her cat in her sleep. "She was crazy about that cat," she said of her patient.
Standard treatments include the medication clonazepam, which relaxes the muscles during sleep. Other doctors say hypnosis or stress-relieving interventions can work in some cases.
Cartwright successfully treated an athletic director at a local college who was charged with home invasion and intent to rape the teenager.
He often kept an eye on two neighbors' homes and did so before going to sleep one night. But an hour later, he got up sleepwalking, thinking he saw lights on in another house across the street.
Asleep, he walked into the unlocked home.
"He wandered into the bedroom where the teenage daughter was asleep with her boyfriend," said Cartwright. "She said that he touched her on her thigh and it woke her and she screamed.
"He was very confused, partially asleep and partially awake," she said. The girl recognized the neighbor and made sure he got home safely. But her mother, who had been away that night, reported the "crime."
The man was arrested on five felonies, but Cartwright's testimony helped to have the case dismissed.
"He was a lovely guy, just as nice a person as you would want to meet," she said. "He didn't hurt anyone."
Another purported sleepwalker she defended was not so lucky.
In 1999, Scott Falater of Arizona was found guilty of stabbing his wife 44 times. Though he never denied killing his wife, Yarmilla, Falater said in his defense that he had a history of sleepwalking.
Falater's neighbor testified that he watched over his backyard fence as the father of two went inside his house to wash his hands, ordered his dog to lie down, then rolled his wife's body into the pool and held her head under water.
He had been trying to fix a faulty swimming pool pump, and defense lawyers suggested his wife may have interrupted him while he was trying again to fix the pump in his sleep, triggering a violent reaction.
"He had been under a lot of pressure," said Cartwright said. "The cops woke him up with the noise. He jumped up and thought there was an invader and rushed down stairs. When they asked him how many people were in the house, he said 'four,' two kids and himself and his wife. He didn't know she was dead."
Cartwright, who wrote up the case in a 2004 issue of the American Journal of Psychiatry, said she is still convinced he was innocent.
One of the misconceptions about sleepwalking is that somnambulists stumble and fall, but according to Cartwright, they have all their motor skills.
"They are very good at navigating space," she said. "They can go up and down stairs and drive a car. They can navigate in the world, but the face recognition is off."