Sleepwalking, Violence and Desire in the Middle Ages

William MacLehose

This study discusses the phenomenon of medieval sleepwalking as a disorder of body and soul. In the thirteenth and early fourteenth centuries, medical and natural philosophical writers began to identify the category of the sleepwalker with unusual precision: the most common example of the disorder involved an aristocrat who rose, armed himself, and mounted his horse, all the while imagining that he was fighting enemies or hunting deer. Explanations for this extraordinary behaviour involved the physiology of sleep and the functioning of the brain. In particular, theorists believed that the imagination, a storehouse of images located towards the front of the brain, took control because reason and sensation had been disabled during sleep. As a consequence, daytime fears and traumas could come to the fore for some sleepers, causing them to act and react in their sleep in ways they could not, or were not willing to do, in their waking, rational state. As such, medieval medical writers viewed sleepwalking as a dangerous, disordered state which called into question the Aristotelian divide between waking and sleeping as well as the categories of reason, sensation and voluntary motion.