Killer Sleep: An Overview of Homicidal Somnambulism

While the phenomenon of sleepwalking is typically a benign and almost comedic sight to see, this innocent and bizarre behavior has the potential to turn violent and traumatic. In fact, homicidal sleepwalking cases are prevalent enough throughout history that they have attracted interest from forensic psychologists globally. This blog post will be devoted to understanding the neurobiology behind sleepwalking, DSM criteria for sleepwalking and terror disorders, and finished with recaps of a few cases of homicidal sleepwalking. 

The concept of sleepwalking, also known as somnambulism, is perplexing, to say the least; how can a person physically carry out activities while they are fast asleep? It is a question that has plagued victims of the disorder as well as juries overseeing cases of violent somnambulism. Research has been conducted to understand just what is going on in the brains of those who seem to act out their dream life. 

In order to understand when somnambulism typically occurs during the night, a quick debriefing of human sleep stages is helpful. Human sleep is divided into 2 distinct subsets: rapid eye movement sleep (REM) and non-rapid-eye-movement sleep (NREM). There are three stages of NREM that occur throughout the night- N1 during sleep onset, N2 is known as light sleep, and N3 is classified as sleep or slow-wave sleep. Sleep disorders are often stage-specific. Somnambulism is known to occur primarily during N3, or slow-wave sleep (Zadara et al., 2013). Other sleep disorders that occur during this phase are sleep terrors and confusional arousals, both of which are relevant in the discussion of violent somnambulism. Sleep disorders such as somnambulism, sleep terrors, and nocturnal enuresis (urinating while asleep) classify as sleep-related behaviors known as parasomnias. Parasomnias are not initiated from REM sleep but are a result of an abnormality in the transition from NREM to REM sleep. This abnormality means that there is no longer the typical atonia (loss of muscle tone) that accompanies REM sleep, meaning individuals can physically act out their sleep behaviors. (Broughton, 1968). 

While somnambulism is typically harmless, there have been almost 70 documented cases throughout history of homicidal sleepwalking. Aside from these murders, there are countless episodes of nonhomicidal sleep violence littered throughout history as well. A forensic psychiatrist named Bonkalo reviewed 50 reports of sleepwalking violence. He was able to highlight common characteristics of the attacks. What he found was that a vast majority (47 of the 50 cases) were committed by men and the ages of the accused individuals ranged from 27-48 years old. Moreover, there was a strong childhood or family history of sleepwalking, nocturnal enuresis, agitation on awakening, and nightmares (Bonkalo, 1974). Since Bonkalo’s report, the interest and research regarding sleepwalking patients have expanded. The current DSM V criteria for sleep arousal, sleepwalking type, disorder are:

  1. Recurrent episodes of incomplete awakening from sleep, usually during the first half of the sleep cycle, accompanied by episodes of getting up from bed and walking around 
  2. While sleepwalking, the individual has a blank, staring face- unresponsive to efforts of communication and difficult to wake up
  3. Little to no memory of dream imagery 
  4. No recall of the episode 
  5. Episodes cause significant distress or impairment of social, occupational, or other areas of functioning
  6. Symptoms cannot be explained by another mental disorder, medical condition, or related to drug abuse or medication  

Sleep terror disorders are usually difficult to separate from sleepwalking disorders. They often begin with abrupt sitting up, panicky screams, and signs of intense fear. The individual may be self-protective and actively resist being held or touched. Events that begin as night terrors may transfer into sleepwalking episodes, and vice versa.  It has been noted that most sleepwalking violence occurs when an individual is under a great deal of stress and suffering from inadequate sleep. This becomes an important detail in somnambulatory homicide cases; most of the accused individuals have typically reported to be under a great deal of stress and not have had enough sleep.

Juries have struggled with the concept that those who are able to commit homicide in their sleep can be oriented well in space, walk, climb, and even drive without harm but not recognize the face of a loved one. One of the most notorious examples involves a man named Ken Parks, who drove 14 miles, killed his mother in law and strangled his father in law, who survived the incident- all while asleep (Walker, 2018). Studies of the neuroanatomy of the visual system have shown that the neural pathways needed for facial recognition are completely different from the pathways needed for movement and detecting other visual stimuli (Ungerleider, 1982; Mesulam, 1994). Additionally, plenty of juries have struggled with the fact that most sleepwalking homicides are unpremeditated, occur without awareness, and are followed by amnesia and strong guilt. Homicides committed during sleep are undoubtedly some of the most baffling and riveting cases in forensic psychology. With an adequate understanding of somnambulism as well as the DSM V criteria, we can delve into some of the homicidal sleepwalking cases throughout history. 

In July 2008,  Brian Thomas strangled his wife inside of their camper while they were on vacation. Mr. Thomas had a long history of night terrors and sleepwalking episodes. It was mentioned by police that when Mr. Thomas regained wakefulness and his deceased wife, struggled to explain what had happened. In hysterics, Mr. Thomas was able to communicate to the police: “Can you send someone? I think I’ve killed my wife. I’ve killed her. Oh my god.”. Thomas had been celebrating his 40th anniversary with his wife at the time. Reports of the incident explained that Mr. Thomas was having a nightmare that someone had been intruding and in that dream, he managed to fight the male intruder and put in him a headlock. He awoke to see that his wife was who was strangled and murdered. Initially, there were ideas of sending Thomas to a psychiatric hospital and for him to plead guilty by reason of insanity. However, it soon became clear that this was not an incident of mental illness, but disordered sleep. The jury came to a formal not guilty verdict and he was released after being held in custody for eight months (Stone, 2009).  Although Brian Thomas was spared a life of imprisonment, he bears the guilt of his wife’s death each and every day, all because of disordered sleep. 

Scott Falater was not as fortunate as Mr. Thomas.  In 2000, Falater was convicted of the first-degree murder of his wife, Yarmila Falater. However, her death was much more violent than that of Mrs. Thomas. On January 17th, 1997, Falater was reported to have stabbed his wife 44 times prior to drowning her in their pool. Falater claims that after failing to repair their pool filter his wife had asked him to fix, he came inside and “crashed in bed … between 9:30 and 10:00 [pm]”. He claims his next conscious memory was standing at the top of his stairs looking down at a police offer whose gun was drawn and asked to keep and hands visible get on the floor. After a testimony by his neighbor who claimed to see Falater put gloves on and roll his wife into their pool to drown her, Scott’s mother and sister testified that he suffered from a history of sleepwalking. His sister claims when they were younger there were incidents where he would just toss her out of his way when she tried to wake him from a sleepwalking episode. Dr. Broughtand and Dr. Cartwright, two leading sleep scientists at the time of the case, testified that they believed he was asleep during the time of the murder and saw her as a threat if she tried to wake him up. The police argued that Falater hid his clothes and the murder weapon, washed himself off, and changed his clothes. Dr. Broughton, on cross-examination, admitted it was unusual to carry out so many different actions during a sleepwalking episode (Pararella, 2021). Falater continues to deny having any memories of the event and claims he will never forgive himself, but he will spend the rest of his life in prison. 

There are plenty of other somnambulism homicide cases where the accused has pled not guilty due to lack of consciousness during the episode.  Some defense attorneys may be more convincing than others, but nevertheless, these crimes are true tragedies- both for the victims and those suffering from the sleep disorder. While most cases of sleepwalking are benign, it is of importance that we recognize warning signs (stress, diminished sleep) of a potentially violent attack before it occurs. 


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Bonkalo A: Impulsive acts and confusional states during incomplete arousal from sleep:

criminological and forensic implications. Psychiatr Q 1974; 48:400–409[Medline]

Ungerleider L, Mishkin M: Two cortical visual systems, in The Analysis of Visual Behavior. Edited by Ingle D, Mansfield R, Goodale M. Cambridge, Mass, MIT Press, 1982, pp 549–586 

Mesulam M: Higher visual functions of the cerebral cortex and their disruption in clinical practice, in Principles and Practice of Ophthalmology. Edited by Albert D, Jakobiec F. Philadelphia, WB Saunders, 1994, pp 2640–2653

Paparella A, Engel S, Resendez M, Effron, L: ‘Sleepwalking’ killer Scott Falater Still Wracked with Guilt Over Murdering Wife. January 28th, 2021 

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).

Walker, M. (2018). Why we sleep. Penguin Books.

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