As the Islamic scholarly elite, or ulema, coalesced as a class of urban intellectuals from the tenth through fifteenth centuries CE, they composed treatises of professional etiquette, or ādāb, to expound the skills and techniques of learning scholars-in-training needed to master. Amid their descriptions of the ulema’s study habits, curricula, and professional conduct to this end, authors of ādāb cited the avoidance of sleep during certain hours of the night as especially important for developing the skill of memorization. As part of their education in this formative era, the ulema were expected to commit countless scholarly texts to memory. They were furthermore expected to be able to draw from this mental library for verbatim, extemporaneous use of such texts throughout their careers. Authors of ādāb therefore intricately described the embodied acts of memorization and recollection that underlay the ulema’s learning, discussing practical strategies their readers might use to maximize their intellectual potential at great length. These strategies were often medical in nature; students were, for example, encouraged to adhere to certain drug and dietary regimens as a means of enhancing their memories. While these perhaps more legible forms of scholarly medicine have received their due share of attention from historians, the medicalization of sleeplessness in medieval Islamic intellectual culture has not. In this paper I will explore how medical thought on the importance of certain hours to the waxing and waning of vital powers permeated the ulema’s circles by the tenth and eleventh centuries. In particular, medical theorists argued that the humorally warm rational spirit facilitating cognition and recollection increased in potency as the night approached, but was typically suppressed by the cooling effect of sleep on the brain. Avoiding sleep at night would allow scholars to avail themselves of this hidden humoral power. I will show that this vivid sense of embodiment helped determine the timing of the ulema’s rigorous study schedule by the twelfth century: dialectics at forenoon, composition at midday, and reading in the evening, with only limited provision for sleep before memorizing texts from dusk until dawn. By documenting the appeal that medical reasoning about limiting one’s sleep held for the ulema as they sought ever more effective strategies to improve their scholarly potential in this era, this paper will bring an understudied dimension of medieval Islamic scholarly identity to light and make an original contribution to the study of premodern medical cultures.