The Defence of Parasomnia – Interpreting Criminal Behaviour

By Tanisha Sharma, BA LL.B 3 rd year, Student Delhi Metropolitan education, GGSIPU.

Parasomnias are a set of sleep disorders characterized as undesired physical occurrences or sensations that occur during the initiation of sleep, throughout sleep, or during arousal from sleep. Sleepwalking, sleep terrors, sleep talking, and sleep paralysis are some of the behavioral symptoms linked with partial arousals from sleep known as parasomnia. It can happen at any age. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) classification & the International Classification of Sleep Disorders (ICSD) classification are two criterion-based classifications for sleep disorders. We recognize this as a medical and psychiatric issue, but our question is whether sleep walking may be utilized as a defense to murder. Will a person A be held accountable if he or she commits an offence while sleeping and dreaming?

“Father of two children and a man who truly loved his wife for almost 40 years was sleeping in a camper van with his duly wedded wife Christine. While sleeping Brian Thomas had a dream of a boy racer who broke into their camper van in which both of them were sleeping. It was in his Dream while fighting the intruder brain ended up strangling his wife to death.”

Will the principles of Actus Reus (physical elements of crime) and Mens Rea (motives and intention to commit crime) apply in this case? While answering these questions this article will further evaluate the Psycho-legal aspects of this defense in terms of subjectivity and objectivity and theory of Dream enactment and dream interpretation by Sigmund Freud.


The above-mentioned case became infamous as the Brian Thomas case, in which his council and psychiatrists debated over homicidal sleep walking and the fact that he did not intend to kill his beloved wife and that his actions were not directed to do so. Brian was diagnosed with sleep disorder in this case, but psychiatrists were apprehensive that this could be misused as a legal defense in the future. Here are some case studies and evidences that can help us identifying whether a person is musing the defense or not? How to distinguish between a disorder and just one single episode of sleep walking?

As per the guidelines of DSM – V sleep walking is a psychopathological disorder and must be diagnosed once a psychiatrist considers all the symptoms and conditions a person experiences. One episode of sleepwalking should not be considered a symptom of the said disorder as a defense in court! As per a study by lancet the sleepwalker’s brain exhibited no activity in the processes connected with purpose, but it did have activity in emotional and movement-related areas.

Rosalind Cartwright of the Sleep Disorder Service and Research Center in Chicago says, “Our judgment is off and our tendency to act out emotionally is on.” She believes that a proven diagnosis of sleepwalking would be a good legal defense, but that more tests are needed to determine who has a true sleep problem. Therefore a standardized, organized and objective procedure is essential to investigate such cases of extraordinary nature.

Relationship between dreams and reality. As per the self-organization theory of dreaming, the sleeping brain is a self-organizing device capable of combining discontinuous and incongruent neuronal signals (i.e., separate elements of dreams) into a reasonably continuous narrative throughout sleep. Another theory by Sigmund Freud, Dream analysis has thus been an important psychoanalytic technique since Freud regarded dreams as a royal path to the unconscious. Our mind often works like a projector that projects fears, desires and sexual motives while we are sleep.

These are the two prominent theories of dreams and their significance elucidated by psychologists.

Moving ahead with the question that can dreams have an effect on reality? Can the two state of Consciousness and sub consciousness intersect? According to J. Allan Hobson and Robert McCarley’s activation-synthesis model of dreaming, circuits in the brain become active during REM sleep, causing the amygdala and hippocampus to generate an array of electrical impulses. Have you ever experienced that you are constantly running in your dream and suddenly you fall into a pit! That is the moment when you wake up have you ever had a dream where you are constantly running and then abruptly fall into a pit? That’s when you wake up twitching with the distinct impression that you’ve fallen for real. This phenomena is what we call as sleep start or Hypnic jerks. 

In a recent by Mark. S Blumberg and Alan M.Plumeau from department of psychology and neurosciences, from University of Iowa, Iowa City, USA have come up with the idea Dream enactment a relationship between our state of dreams and physical body movements we make when we are asleep. That talks about sleep behavior disorder and violent motor manifestations. During REM sleep, patients with REM sleep behavior disorder (RBD) have increased muscle tone and exaggerated twitching. RBD is often associated with aggressive limb gestures and complex actions that may often appear to involve the execution and enactment of dreams. These actions are assumed to be the product of a malfunction in the brainstem’s producing neural circuitry, which reveals cortically produced dreams. This elaborates a medical evidence. that is possible for a person fighting in dreams can actual execute physical movements while the person is still sleeping. Certain actions reported in such enactments are Shouting, Swearing, Flailing, Grabbing, Punching, Kicking, Jumping and Leaping.

The legal liability We see that this condition requires a medical history a single episode cannot account for sleep behaviour disorder. Since such cases are ambiguous in nature the level of consciousness of the accused during the episode is critical because it lets the jury decide if the episode is consistent with a parasomnic episode. The diagnoses must come from a licenced practitioner. And as far as involvement of actus reus and mens rea we therefore see that this condition is a classified disorder under international Classification of Diseases and Diagnostic and Statistical Manual of Mental Disorders. Which makes such cases defence of insanity where consciousness and arousal to attend any particular information is absent.

According to Lord Denning’s concept of automatism in the case of Bratty, automatism is:  An act which is done by the muscles without any control by the mind such as a spasm, a reflex action or a convulsion; or an act done by a person who is not conscious of what he is doing such as an act done whilst suffering from concussion or whilst sleepwalking.

We can clearly prevent abuse of such a nuanced defence, and when it comes to liability, the Latin maxim In somno voluntas non erat libera (A sleeping person has no free will) addresses all of our questions about mens rea and actus reus involvement.

Finally, we see that medical research and psychological investigations are constantly developing in such matters; others argue that about the cases, possibilities, and episodes of dreamless sleep where a person’s consciousness is triggered, medical research and psychological investigations are constantly evolving. Since such hypotheses and arguments have a significant effect on procedural technicalities and legal decisions, the court and lawyers must ensure that a standard and objective procedure path map is in place to address such matters in order to prevent injustice.


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