What is sleep forensics? It’s the use of sleep medicine, science, and expertise in the investigation of violent, strange, and irrational behavior related to sleep—and crimes that may stem from these behaviors. Yep, there’s room for a sleep specialist character on your (or my) favorite crime procedural show.
Experts who work in the field of sleep forensic medicine make contributions to investigations and legal cases in a number of different ways. They perform medical examinations and sleep studies, and make diagnoses for sleep and sleep-related disorders. They work with law enforcement and legal professionals on cases where sleep may be a factor. They provide expert testimony for criminal and civil trials. The also research and study the latest in sleep science, and other physical and psychological conditions that might contribute to violent and dangerous behavior.
When sleep is violent
What could lead a sleeping person to enact dangerous, violent behavior while in some stage of sleep? The answer to that question is deeply complicated. You’ll often hear the term parasomnia in connection with sleep-related violence. I’ll talk briefly about what that term means.
Parasomnias are a broad category of disorders and conditions that disrupt sleep and lead to unwanted behaviors, psychological states, and experiences related to sleep. There are many types of parasomnias, and collectively, parasomnias occur in an estimated 10 percent of general population. The range of parasomnias is wide. Sleep talking is a parasomnia. So is sleep eating. Sleep terrors in children are form of parasomnia.
Several parasomnias carry risks for sleep-related accidents and injury, to the sleeper and to other people the sleeper comes in contact with. Parasomnias can be caused by sleep disorders, medical conditions both physical and psychological, and interactions with medications, drugs, and alcohol, or for reasons sleep physicians can’t identify. There appears to be strong genetic connection to some parasomnias, including sleepwalking.
Sleep-related conditions that can result in disturbing, dangerous, and violent behavior include:
You might think criminal cases that require an expert in sleep happen once in a blue moon. Not so. While not common, sleep-related crimes happen more often than you may think. Breakthroughs in sleep science have deepened our understanding of the intricacies of sleep, and the complex, porous lines between sleeping and waking. Forensic experts point out that what we now can identify as sleep-related violence can be mistaken for intentional violence against oneself or others.
The earliest criminal case in the U.S. involving the so-called “sleepwalking defense” came in 1846. A man named Albert Tirrell was found not guilty of killing his mistress and setting fire to a brothel in Boston. Tirrell’s defense claimed he was a sleepwalker, with a history of agitated and violent behavior during sleepwalking episodes that began when he was a young child.
One of the most famous cases of sleep-related crime—and a case that in some ways echoes Albert Tirrell—is that of Kenneth Parks. In 1987, Parks rose one night from bed, drove roughly 14 miles to his in-laws’ house, and assaulted them. He bludgeoned his mother-in-law to death and attacked his father-in-law, who survived. Parks then drove to a local police station and confessed to the killings. Parks said he’d been sleepwalking the entire time, through the drive, the attack, and even at the police station. He said he hadn’t been aware of what he was doing and had only trace memories of the events.
Parks had a long history, dating back to his childhood, of complex and extended sleepwalking episodes triggered by stress. Around the time of the killings, Parks was under significant stress: he had a serious gambling problem, he’d been fired from his job, and was facing embezzling charges. Parks underwent sleep testing that showed irregular brain activity during his sleep, which were consistent with some types of parasomnia. Also, when he arrived at the police station, Parks had serious wounds to both his hands—but police said he did not appear to be experiencing pain. This suggested a dissociative state that can be part of sleepwalking. Parks was acquitted of all charges.
In 2000, Scott Falater was convicted of first-degree murder in the slaying of his wife, Yarmila Falater. Falater admitted to killing his wife, “stabbing [her], stashing the knife and some bloody clothes in the back of his Volvo, then dragging her to the pool at their Phoenix home and holding her head under water,” as reported in the Los Angeles Times.
But Falater said he’d been sleepwalking when he committed these acts, and had no memory of any of the events. Sleep experts who testified at Falater’s trial said he had been sleep deprived and under stress at the time of the killing, and that he had a family history of sleepwalking. Falater was sentenced to life in prison without the possibility of parole.
In 2008, Christine Thomas was strangled to death by her husband, Brian, while the British couple were vacationing in a camper in Wales. Brian Thomas was charged with murder. He said he’d been having an intense nightmare in which he was fighting off an intruder, when he awakened and realized he’d strangled his wife. Sleep experts said Thomas had experienced night terrors. Night terrors are a very intense and frightening type of sleep episode, which can be accompanied by screaming as well as sudden, violent movement or fighting. Forensic sleep evidence led to the prosecution asking for the case to be dropped and Thomas to be found not guilty.
There are at least two currently ongoing murder cases in the U.S. that involve sleep as part of the defense:
Though it remains too-little understood, sleep violence is a real danger—one the legal world is still just waking up to. Sleep forensic specialists are at the forefront of bridging the gaps between the science of sleep violence and the legal ramifications for sleep-related crimes.