Sleepwalking Violence: A Sleep Disorder, a Legal Dilemma, and a Psychological Challenge

One of the difficulties juries have expressed when faced with a case of sleepwalking violence is understanding how it is possible for an accused person to orient well in space, walk, climb, and drive without harm and yet not recognize the face of a loved one the sleepwalker is attacking. Studies of the neuroanatomy of the visual system have established that the pathways involved in guiding movement and in facial recognition are different. The pathway for visually guided movement terminates in the posterior parietal cortex, while that for recognizing faces and assigning meaning to visual stimuli terminates in the midtemporal cortex (37, 38).

Broughton (15) reported that sleepwalkers have a greater delay in reaction to visual stimuli when they are aroused from slow-wave sleep than do comparison subjects, and this finding was also noted by Kales et al. (13). There are other apparent perceptual difficulties during sleepwalking episodes. In sleepwalking violence the sleepwalkers do not appear to hear their victims cry out, nor do they register pain when they hurt themselves. These suggest hormonal changes and/or brain pathways that may still be “asleep” while complex motor behaviors take place.

Juries have questioned how an accused person is able to carry out complex, nonviolent, seemingly purposeful motor behaviors over extended periods of time, such as working on a motorbike (20), without waking before acting violently. There are now several published cases in which prior long-distance driving took place (4, 10, 39). The total time before consciousness fully returns has been estimated to be as long as an hour. However, how or why some complex, but benign, behavior suddenly shifts into an emergency fight-or-flight response is puzzling.

Aggressive behaviors that erupt from sleep and are followed by amnesia suggest a dissociative disorder. Hartman et al. (40) tested the hypothesis that sleepwalkers would have more psychological trauma in their histories and would score higher on a waking test of proneness to dissociate than would comparison subjects. Their data did not support this. In fact, sleepwalking violence has not been associated with any specific psychopathology. The results of personality studies are most often within normal limits. Only tendencies to overcontrol emotion and to have compulsive behaviors have been noted (4, 10, 41).

Perhaps the most vexing question for juries is that of motivation, since these attacks appear to be unpremeditated, to take place without awareness during the event, and to be followed by retrograde amnesia and remorse. Motivation was one factor for ruling out a diagnosis of sleepwalking violence in two forensic cases studied in my laboratory. In both, prior marital discord due to continuing infidelity suggested a possible motivation for the aggressive attack on the wife. Forensic reports often note extensive sleep deprivation before an aggressive event and suggest that the sleep loss was secondary to psychological stress (5, 6, 10). Perhaps the sleepwalker’s “integrated, goal-directed behavior,” noted by Bonkalo (16), represents a response to the waking stress.

In the belief that detailed descriptions provide useful guides to further research, I am presenting a new case of homicide (Mr. A) for which the defense argued that the act took place during a sleepwalking episode. An extensive pretrial workup included a complete neurological examination, psychological testing by a court-appointed psychologist, 4 nights of all-night sleep recording, and the development of a family pedigree of relatives with a history of sleepwalking, nocturnal enuresis, and sleep terrors. These data were ordered by the court to parallel those developed for the trial of another homicide defendant, Mr. B, and were included in a published report on that case (10). Although the two accused men differ markedly in demographic characteristics, the homicides have many common features. Mr. A was older than Mr. B (42 versus 22 years), was better educated (Mr. A was an electrical engineer with an additional M.B.A. degree and Mr. B had not finished high school), and had higher social class (upper middle class) and income (Mr. B was unemployed and deeply in debt). Mr. A was 5 ft. 9 in. tall and was described as a wiry “nerd,” whereas Mr. B was a 6 ft. 5 in., 280-lb. “gentle giant.”

At the time of his wife’s death, Mr. A was employed at Motorola’s semiconductor plant in Arizona as a product manager with an annual income of about $100,000. He had been married for 20 years to his high school sweetheart. There were two teenage children, a daughter 15 and a son 12. He and his wife were both raised in the Roman Catholic Church. Mr. A became an active and committed member of the Church of Jesus Christ of Latter-Day Saints before his marriage. His wife joined him in this affiliation after they married. As Mormons, they neither smoked nor drank alcohol. Accounts of the marriage all describe them as a close and loving family, active in their community, and without financial, health, or marital difficulties. The children told police that differences between their parents were few and settled by discussions.

Mr. A is the eldest of five children. His parents both had problems involving alcoholism, and his father was abusive when drinking. Although he was not the target, Mr. A witnessed the abuse of his mother. The parents divorced when he was 17. His wife’s parents had been divorced earlier, and she was helpful to him during this upsetting period. He describes her as his best friend and the only girl he ever dated. After high school they attended separate colleges but continued dating during holidays and summers. They married in 1976, when they were both 20. Their long, happy marriage ended with her sudden death at his hands.

In April of 1996, 9 months before his wife was killed, Mr. A entered a period of high work-related stress. He was assigned to be project manager of a new product, a chip to be used in the disk drive of computers. It was Mr. A’s judgment that the project was doomed to failure as his company was far behind the competition in this development. He continued to work hard at trying to solve the problem. Work success was a very important element in his self-esteem. He held himself to a high level of competence. He was also afraid that he would be viewed responsible for a failure that would cost the company millions of dollars and would lead to the loss of jobs for members of his team. By December he felt he must advise upper management that the project should be shut down. He felt alone in his dilemma, caught between being seen as a quitter by those above him and as a betrayer by those who worked under him. He put in long hours and went to bed late as he approached a decision point. He reports feeling exhausted and depressed, and he began using caffeine tablets to stay awake at work. His sleep pattern alternated between 2 to 4 late nights of short, poor-quality sleep followed by a night of “crashing” early into a night of catch-up sleep.

The day of the homicide Mr. A arrived home between 7:00 and 7:30 p.m. and had dinner with his wife and children. During dinner he discussed his work problem with his wife. She advised him to just smile and tell his manager and team what they wanted to hear. He remembers saying that he had gone along too much already. His wife also asked him to see what was wrong with the filter for their backyard swimming pool. After dinner, his wife watched television, the children did homework, and Mr. A worked at his computer, preparing materials for teaching a church youth group the next morning. He led this group every morning before work. The children went to bed at 9:00 p.m. Mr. A went out to inspect the pool motor problem. He started work on it but reports that it became too dark for him to finish the repair. He put his tools into the trunk of his car in the garage. His wife was still downstairs on the couch watching television. He remembers kissing her good night and going up to bed somewhere between 9:30 and 10:00 p.m. He changed into pajama bottoms but did not remove his contact lenses before “crashing” into sleep. This is his last memory of the day.

The next memory Mr. A reports is of waking in bed and hearing his dogs barking and voices down below. He ran downstairs. Before he reached the bottom he was met by police with drawn guns, who ordered him to lie face down, handcuffed him, and asked, “How many people are in the house?” He answered, “Four,” unaware that his wife was lying dead in the pool. Mr. A was placed in the back of a squad car, where he waited for about an hour while the police completed their initial investigation. He could hear the police and emergency personnel close to the car talking about what was happening. From this conversation he gathered that his wife had been badly hurt. He thought the police must be hunting for the responsible person. He did not realize that she was dead nor that he was the one to be accused. That did not become clear to him until he was taken to the Phoenix police department for interrogation and the interviewing detective asked him repeatedly about his motive for killing her.

The police were called to the house by a neighbor who dialed 911 after looking over a common wall to see why dogs were barking and a woman screaming. As he reported to the police, the neighbor went to bed about 10:00 p.m. and got up about 10:30. What he saw was a body lying beside the pool. There was a light on in a second-story room of Mr. A’s house. Through the window he had a partial view of Mr. A moving from one room to another. Mr. A then reappeared in the backyard and stood staring blankly over the body; then he returned to the house but came back out through the garage door, pulling on heavy canvas gloves. The neighbor reports that he saw Mr. A drag the body to the edge of the pool and roll it into the water. When he realized that this was Mr. A’s wife, he called the police. The record shows that the call was made at 10:56 p.m. When the neighbor returned to look over the wall again, he saw the body floating in the pool. Mr. A was no longer visible. The presumption is that he had gone back to bed and was asleep until the noise of the police woke him.

The medical examiner reported that Ms. A had suffered multiple stab wounds, 44 in all. There was blood beside the pool and more found in the pool. There were bloodstains on Mr. A’s work clothes, which the police found in the trunk of his car, and there was more blood on a knife. Some blood remained on Mr. A’s neck, and he had a fresh bandage on one hand. He seemed puzzled when these were pointed out to him during the videotaped interrogation and had no explanation of how these had been acquired.

The report from a medical examination of Mr. A indicates that he is in good health with an unremarkable health history. A neurological workup ruled out a seizure disorder or tumor on the basis of a clinical EEG in both waking and sleep and a magnetic resonance imaging scan of the brain. The report of the neurologist concludes that in his opinion the homicide was the result of a parasomnia rather than any primary neurological condition. A forensic psychologist administered an extensive battery of standardized tests to rule out psychopathology. These included an MMPI, a Thematic Apperception Test, a Rorschach test, and a sentence completion test. The results of these were all also reported to be within normal limits. Both children were interviewed, as were Mr. A’s mother and father, in the search for some explanation for this bewildering event. The children had slept through the attack. They did not hear their mother’s cries. They agreed that there was no dissension between their parents.

A search of previous homicides led the defense attorneys to the case of Mr. B, in which the accused was acquitted on the grounds that he was sleepwalking. In Canadian and British law this was termed a “noninsane automatism.” Fenwick (6) quoted the legal definition as, “The deed does not make a man guilty unless his mind is guilty. If, at the time of the offense, there is an absence of mind, so that any action carried out was automatic, then in law the defense of automatism is possible.”

Interviews of Mr. A’s relatives supplied many instances of his sleepwalking as a child. One later example, when he was 20 years old, involved some violence toward a sister when she attempted to restrain him as he tried to leave the house dressed in pajamas at about midnight.

As I had been an advisor on the case of Mr. B, I was asked to review documents relevant to the possibility that Mr. A had also been sleepwalking during the attack on his wife. Many similarities between the two cases were noted, as was their consistency with the Bonkalo criteria:

After reviewing the documents in the case of Mr. A, the family pedigree (Figure 1), the psychologist’s report and the raw test responses, the medical and police reports, and the videotape of his initial police interrogation, I could not rule out the possibility of a sleep disorder. I requested an interview with Mr. A and asked that sleep studies be conducted. If a behavioral arousal from early non-REM sleep occurred or there were a significantly higher number of EEG arousals than expected, in the absence of other causes (indications of sleep apnea or narcolepsy), support would be added for this disorder. Four nights were requested, to allow him to adapt to the experimental setting, although the difference between the emotional circumstances of these nights to those of his typical home sleep could not be controlled. Three consecutive nights were uninterrupted. On the fourth night, the technician attempted to stimulate an arousal by using a sound stimulus. As the research identifying low delta power in these patients had not yet been published, these records were not subjected to power spectral analysis. They were scored according to the standard sleep stage criteria (27) by the hospital technician and subsequently rescored by two independent, well-experienced sleep specialists. All nights illustrate a large number of arousals from early non-REM sleep and a significantly higher total number than expected on the basis of sex-specific age norms: the mean number of arousals for 40–49-year-old men is 4.67 (42, p. 58), and the mean for Mr. A across three nights was 26.5 (Figure 2).

After an interview with Mr. A, I compared what I could deduce of his psychological functioning during and following the episode to that of Mr. B on the basis of the parallel documents from his file and my interview with each of them (Table 2).

In neither case was the prosecution able to develop a motive for the attack: no financial gain, no bad relationship, no infidelity, only the demoralizing psychological stress of a sense of impending humiliation and failure to be confronted the next day. This was also suggested as a possible explanation in an earlier case (2). In both Mr. A and Mr. B there was an intent to “do the right thing”; in the case of Mr. B, this was to tell his in-laws about his compulsive gambling and resulting debts, and for Mr. A this was to successfully finish the pool repair before telling his manager and team that he could not bring the work project to a satisfactory conclusion. Each man was halted while attempting an ego-restorative act and lashed out as if his life was in danger. Without the ability to recognize the person who stood in his way and while the higher cortical areas controlling judgment were partially blocked, the primitive impulse to attack took over. Only after the trial, when I reviewed the literature for this report, did the fact that Mr. A had begun using caffeine tablets to maintain wakefulness suggest a possible effect on his sleep. As a Mormon, Mr. A had not drunk coffee or tea for many years. The effect of the new substance may well have been a precipitating factor in an abnormal arousal (9, 19).