Middle English literature is intimately concerned with sleep and the spaces in which it takes place. In the medieval English imagination, sleep is an embodied and culturally determined act. It is both performed and interpreted by characters and contemporaries, subject to a particular habitus and understood through particular hermeneutic lenses. While illuminating the intersecting medical and moral discourses by which it is shaped, sleep also sheds light on subjects in favour of which it has hitherto been overlooked: what sleep can enable (dreams and dream poetry) or what it can stand in for or supersede (desire and sex). This book argues that sleep mediates thematic concerns and questions in ways that have ethical, affective and oneiric implications. At the same time, it offers important contributions to understanding different Middle English genres: romance, dream vision, drama and fabliau.