This article conceptualizes sleep as a social fact. Far from being a simple biological necessity, sleep is imbued with meaning. We argue that in the "knowledge society," science and technology play a key role in producing the social meaning of sleep and in grating validity to certain styles of "sleep knowledge." Paradoxically, in their search for "valid" knowledge, actors turn to science while at the same time science often offers provisional and contested knowledge. In particular, the modern sleep laboratory and mobile self-tracking technologies prove to be epistemically productive. They open up arenas for (experimental) practices that contribute to producing, applying, and legitimizing sleep knowledge. The article traces the historical processes that led to the invention of the modern sleep lab and current mobile technologies and sheds light on the questions of how knowledge about sleep and its disorders is produced, which sleep knowledge people view as valid, and how this attribution of validity is legitimized. Furthermore, the boundaries between sleep lab and society at large are permeable. Scientific knowledge leaves the lab and enters the social stage, which is why the scientific ideal of objectivity directly encounters the prevailing social and subjective knowledge. In addition to providing the conceptual outline for this HSR Special Issue on "Sleep, Knowledge, Technology," the article provides synopses of its nine thematic contributions.

Historical Social Research, 48(2), 7-22