Medieval attempts to understand nocturnal emissions – involuntary bodily excretions during sleep which were identified as morally ambiguous – became extensive explorations of the unique and problematic features of sleep and the mental state it produced. During the twelfth and thirteenth centuries, nocturnal pollutions became the object of an intensive scrutiny of sleep as a site of moral concern. Causal explanations often centred on human psychology, in particular the unusual status of the sleeping mind, in an attempt to understand the intricate ways in which mind, body and soul were uniquely bound together in sleep. The mental states before, during and after sleep were understood to interact with one another in complex ways which centred on questions of culpability and its lack. A comparison of medical, natural-philosophical, theological and canon law materials discussing nocturnal pollution reveals a preoccupation with the sleeper’s mind as exceptional, uncontrollable and problematic
