In the early 1920s, the Swiss psychiatrist J. Kläsi, working under the directorship of E. Bleuler at Burghölzli, the Psychiatric Clinic of the University of Zürich, proposed the treatment of schizophrenia by prolonged sleep therapy induced by the hypnotic Somnifen. Judging from contemporary literature, Kläsi's proposal, which was based upon clinical experience, was accepted by many European psychiatrists, especially those in German-speaking countries. Despite some doubts as to the effectiveness of the therapy and the relatively high mortality rate associated with its use, Somnifen and other related sleep-inducing compounds, were consistently advocated by Burghölzli psychiatrists for at least a decade. It is proposed that the insistence on the use of sleep inducing compounds in the therapy of mental disorders was based on the desperation of psychiatrists lacking effective treatment of schizophrenia. The use of prolonged sleep therapy waned in the mid-1930s with the emergence of other therapies, primarily with insulin and cardiazol.