Bachmann’s rules gradually became more flexible as the size of her winnings and losses expanded. One day, she lost $800 in an hour, and then earned $1,200 in forty minutes. Then her luck turned again and she walked away down $4,000. Another time, she lost $3,500 in the morning, earned $5,000 by 1 p.m., and lost another $3,000 in the afternoon. The casino had records of how much she owed and what she’d earned; she’d stopped keeping track herself. Then, one month, she didn’t have enough in her bank account for the electricity bill. She asked her parents for a small loan, and then another. She borrowed $2,000 one month, $2,500 the next. It wasn’t a big deal; they had the money.
Bachmann never had problems with drinking or drugs or overeating. She was a normal mom, with the same highs and lows as everyone else. So the compulsion she felt to gamble-the insistent pull that made her feel distracted or irritable on days when she didn’t visit the casino, the way she found herself thinking about it all the time, the rush she felt on a good run-caught her completely off guard. It was a new sensation, so unexpected that she hardly knew it was a problem until it had taken hold of her life. In retrospect, it seemed like there had been no dividing line. One day it was fun, and the next it was uncontrollable.
By 2001, she was going to the casino every day. She went whenever she fought with her husband or felt unappreciated by her kids. At the tables she was numb and excited, all at once, and her anxieties grew so faint she couldn’t hear them anymore. The high of winning was so immediate. The pain of losing passed so fast.

“You want to be a big shot,” her mother told her when Bachmann called to borrow more money. “You keep gambling because you want the attention.”
That wasn’t it, though. “I just wanted to feel good at something,” she said to me. “This was the only thing I’d ever done where it seemed like I had a skill.”
By the summer of 2001, Bachmann’s debts to Harrah’s hit $20,000. She had been keeping the losses secret from her husband, but when her mother finally cut off the stipends, she broke down and confessed. They hired a bankruptcy attorney, cut up her credit cards, and sat at the kitchen table to write out a plan for a more austere, responsible life. She took her dresses to a used clothing store and withstood the humiliation of a nineteen-year-old turning down almost all of them because, she said, they were out of style.
Eventually, it started to feel like the worst was over. Finally, she thought, the compulsion was gone.
But, of course, it wasn’t even close to the end. Years later, after she had lost everything and had ruined her life and her husband’s, after she had thrown away hundreds of thousands of dollars and her lawyer had argued before the state’s highest court that Angie Bachmann gambled not by choice, but out of habit, and thus shouldn’t bear culpability for her losses, after she had become an object of scorn on the Internet, where people compared her to Jeffrey Dahmer and parents who abuse their kids, she would wonder: How much responsibility do I actually bear?
“I honestly believe anyone in my shoes would have done the same things,” Bachmann told me.
II.
On a July morning in 2008, a desperate man vacationing along the west coast of Wales picked up the phone and called an emergency operator.
“I think I’ve killed my wife,” he said. “Oh my God. I thought someone had broken in. I was fighting with those boys but it was Christine. I must have been dreaming or something. What have I done? What have I done?” [258]
Ten minutes later, police officers arrived to find Brian Thomas crying next to his camper van. The previous night, he explained, he and his wife had been sleeping in the van when young men racing around the parking lot had awoken them. They moved their camper to the edge of the lot and went back to sleep. Then, a few hours later, Thomas woke to find a man in jeans and a black fleece-one of the racers, he thought-lying on top of his wife. He screamed at the man, grabbed him by the throat, and tried to pull him off. It was as if he was reacting automatically, he told the police. The more the man struggled, the harder Thomas squeezed. The man scratched at Thomas’s arm and tried to fight back, but Thomas choked, tighter and tighter, and eventually the man stopped moving. Then, Thomas realized it wasn’t a man in his hands, but his wife. He dropped her body and began gently nudging her shoulder, trying to wake her, asking if she was all right. It was too late.
“I thought somebody had broken in and I strangled her,” Thomas told the police, sobbing. [259] “She’s my world.” [260]
For the next ten months, as Thomas sat in prison awaiting trial, a portrait of the murderer emerged. As a child, Thomas had started sleepwalking, sometimes multiple times each night. He would get out of bed, walk around the house and play with toys or fix himself something to eat and, the next morning, remember nothing about what he had done. It became a family joke. Once a week, it seemed, he would wander into the yard or someone else’s room, all while asleep. It was a habit, his mother would explain when neighbors asked why her son was walking across their lawns, barefoot and in his pajamas. As he grew older, he would wake up with cuts on his feet and no memories of where they had come from. He once swam in a canal without waking. After he married, his wife grew so concerned about the possibility that he might stumble out of the house and into traffic that she locked the door and slept with the keys under her pillow. Every night, the couple would crawl into bed and “have a kiss and a cuddle,” Thomas later said, and then he would go to his own room and sleep in his own bed. Otherwise his restless tossing and turning, the shouting and grunting and occasional wanderings, would keep Christine up all night.
“Sleepwalking is a reminder that wake and sleep are not mutually exclusive,” Mark Mahowald, a professor of neurology at the University of Minnesota and a pioneer in understanding sleep behaviors, told me. “The part of your brain that monitors your behavior is asleep, but the parts capable of very complex activities are awake. The problem is that there’s nothing guiding the brain except for basic patterns, your most basic habits. You follow what exists in your head, because you’re not capable of making a choice.”
By law, the police had to prosecute Thomas for the murder. But all evidence seemed to indicate that he and his wife had a happy marriage prior to that awful night. There wasn’t any history of abuse. They had two grown daughters and had recently booked a Mediterranean cruise to celebrate their fortieth wedding anniversary. Prosecutors asked a sleep specialist-Dr. Chris Idzikowski of the Edinburgh Sleep Centre-to examine Thomas and evaluate a theory: that he had been unconscious when he killed his wife. In two separate sessions, one in Idzikowski’s laboratory and the other inside the prison, the researcher applied sensors all over Thomas’s body and measured his brain waves, eye movement, chin and leg muscles, nasal airflow, respiratory effort, and oxygen levels while he slept.
Thomas wasn’t the first person to argue that he had committed a crime while sleeping and thus, by extension, should not be held responsible for his deed. There’s a long history of wrongdoers contending they aren’t culpable due to “automatism,” as sleepwalking and other unconscious behaviors are known. And in the past decade, as our understanding of the neurology of habits and free will has become more sophisticated, those defenses have become more compelling. Society, as embodied by our courts and juries, has agreed that some habits are so powerful that they overwhelm our capacity to make choices, and thus we’re not responsible for what we do.

Sleepwalking is an odd outgrowth of a normal aspect of how our brains work while we slumber. Most of the time, as our bodies move in and out of different phases of rest, our most primitive neurological structure-the brain stem-paralyzes our limbs and nervous system, allowing our brains to experience dreams without our bodies moving. Usually, people can make the transition in and out of paralysis multiple times each night without any problems. Within neurology, it’s known as the “switch.”
Some people’s brains, though, experience switching errors. They go into incomplete paralysis as they sleep, and their bodies are active while they dream or pass between sleep phases. This is the root cause of sleepwalking and for the majority of sufferers, it is an annoying but benign problem. [261] Someone might dream about eating a cake, for instance, and the next morning find a ravaged box of doughnuts in the kitchen. Someone will dream about going to the bathroom, and later discover a wet spot in the hall. Sleepwalkers can behave in complex ways-for instance, they can open their eyes, see, move around, and drive a car or cook a meal-all while essentially unconscious, because the parts of their brain associated with seeing, walking, driving, and cooking can function while they are asleep without input from the brain’s more