Sleep disorders have received growing public and scientific attention in the last decades. Scientific research and publications on sleeplessness are ongoing and considerable progress has been made on the medical understanding of sleep. And yet, insomnia affects an ever-growing number of people around the globe and remains both a difficult and common complaint general practitioners have to deal with on a daily basis. Sleeplessness is not new, although its transformation from a state of accepted wake to that of exasperating insomnia is a relatively recent transition in which, this article argues, Western medicine took an active part. In the 19th century, the theorisation of different nervous disorders and later of neurasthenia shaped the transformation of insomnia from a constituent of everyday life into a pathology. Based on research in French medical journals published in the second half of the 19th century, this article retraces a succession of medical paradigms for sleeplessness, including ‘symptomatic insomnia', ‘nervous insomnia' and interestingly, ‘insomnia' as a key element in neurasthenia theories. The analysis of medical discourse in all successive theories reveals the decisive influence of physicians in the medicalisation of insomnia, their sociocultural representations echoing patient's complaints as well as professional imperatives.