Sleepwalking and Murder in the Middle Ages

In the early hours of May 23, 1987, Kenneth James Parks, a 23-year-old man, left his house which he shared with his wife and child, and drove 23 kilometres to his in-laws home, where he used a tire iron and a kitchen knife to kill his mother-in-law and leave his father-in-law severely wounded. Kenneth then drove to the police station, where shaking and covered with blood, cried out, “I just killed someone with my bare hands; oh my God, I just killed someone…”

This famous Canadian story is one of the very few known cases of murder by sleepwalking. Perhaps the earliest account of such a homicide comes from the writings of Guillaume de Montlauzun, who was a professor of canon law at the University of Toulouse in the early 14th century. He tells of when he was a student in Paris, and “an Englishman who was my fellow student and who, sleeping naturally, was so imprinted with the depth of his sleep that, coming out of the Church of Saint-Benedict in Paris, he went to the Seine at night and there killed a child, then he came back, still asleep, and went back to bed.”


The topic of violence and sleepwalking in the Middle Ages has been explored by three historians. Alain Boureau included it as part of his book Satan the Heretic: The Birth of Demonology in the Medieval West, which was published in 2004. More recently, William MacLehose has an article in the journal Culture, Medicine and Psychiatry entitled ‘Sleepwalking, Violence and Desire in the Middle Ages’, while Nicolas Laurent-Bonne gave a paper at this year’s International Congress on Medieval Studies on ‘The Criminal Irresponsibility of a Sleepwalker in Medieval Canon Law’.

Sleepwalking is a sleeping disorder that occurs during a state of deep sleep – the person, while still asleep, can move around, walk and do other activities that they can do while awake. These actions can be quite complex, including having sex and in a few cases physically attacking other people. The Canadian case involving Kenneth James Parks went to court, where evidence was heard from medical experts who confirmed that he was sleepwalking during the time of the incident. Parks was acquitted by jury. There have been a few similar cases in legal records – in some instances the accused was found not guilty, while in others they were convicted.


Around the year 1200 medieval scholars interested in medicine or natural philosophy started looking into why people sleep and sleepwalk. For example, one writer from the period asks:

“It happens that many people get up at night while asleep, take weapons or sticks, or ride a horse. What is the cause of this? What is the remedy?”

For the next hundred years scholars were trying to figure out answers to the riddle of sleepwalking. Albertus Magnus, for example, mentions how he watched a sleeping man “who when asked a question raised himself in his bed, responded, and lay back down, having dismissed the questioners; he was asleep the entire time he did these things.” Meanwhile, the Bolognese professor of medicine, Taddeo Alderotti, explained that he himself would walk in his sleep, and on one occasion he fell from the height of four feet without waking.

Various answers are given to why people talk or walk in their sleep. One theory suggested that while the rational part of the brain is turned off during sleep – which is why we don’t hear or cannot make voluntary movements during this state – the more natural / animalistic part of the mind sometimes does not shut off. Another view suggests that during sleep one’s imagination takes over the rational part of the mind, and takes control of the sleepwalker’s movements.


William MacLehose notes that:

To study the sleepwalker was, for medieval natural philosophers and doctors, a means of exploring the liminal state between waking and sleeping. They recognised that the sleeper could act on desires derived from the waking state, desires otherwise restrained by the rational faculty while awake. The sleeper interacts with the outside world yet does not seem to recognise that world as a waking person would. That is, the external world with which he interacts is based on the internally produced visions stored in his imagination. The world that the sleeper ‘sees’ has little to do with the actual world around him. Instead, the world experienced by the sleeper derives for the most part from the storehouse of images taken from daily life or from thoughts and desires experienced by the sleeper during the day. The sleepwalker was thought to overcome the constraints and fears he felt during the day, in order to satisfy his wants and/or act with bravery and comparative fearlessness.

Medieval writers also understood that sleepwalking could be a danger for others – many of the examples given of this kind of activity was to note how a knight might climb on his horse, draw out a sword and attack other people. If the story that Guillaume de Montlauzun related was true, one’s sleepwalking could lead to deadly results. This led to the question: was the sleepwalker responsible for the violence he caused while sleepwalking? In the early 14th century Pope Clement V wrote that like a young child or madman, the sleepwalker could not be held responsible for his actions. His view would be echoed by the Italian canonist Panormitanus (1386-1445), who commented that the sleepwalker “may endure a wrong, but not produce one; and what is done by him is considered as if a four-footed animal had done it or as if some tile had fallen.”

William MacLehose’s article ‘Sleepwalking, Violence and Desire in the Middle Ages’ appears in Culture, Medicine and Psychiatry Vol.37:4 (2013). Click here for more details about Alain Boureau’s book Satan the Heretic: The Birth of Demonology in the Medieval West and click here to read the abstract to Nicolas Laurent-Bonne’s conference paper.


Top Image: The Sleepwalker by Édouard Rosset-Granger (1853–1934)