Sleeplessness was a quotidian yet challenging problem for medical practitioners in Britain and America in the nineteenth and early twentieth centuries. While physiologists endeavored to unravel the secrets of sleep by examining the brain, in the clinic doctors looked to the gut as a site through which sleeplessness was both caused and cured. This article explores the gut-brain axis in medical literature on sleep and sleep loss in this period. It argues that despite the lack of a coherent understanding of the gut-brain connection, the digestive system was central to how physiologists and clinicians approached sleeplessness. It employs Victorian physician Joseph Mortimer Granville’s (1833–1900) concept of “visceral consciousness” to better understand the varied and often contradictory explanatory constellations that emerged to elucidate the role of digestion in sleeplessness.