Jakob Klaesi (29 May 1883 – 17 August 1980) was a Swiss psychiatrist most notable for his contributions to the sleep therapy[2] and his phenomenological analysis of expression.
From 1903 to 1909, Klaesi studied medicine in Zurich, Kiel and Munich; in 1912 he received his doctorate in Zurich and was then trained as a psychiatrist.
From 1933 he was extraordinary Professor, 1936-53 full professor of psychiatry at University of Bern (rector from 1950 to 1951 ) and director of the Psychiatric Clinic Waldau beginning 1 April 1933.
He set up colonies for the sick, and in 1934, he founded the psychiatric clinic of Berne.
As a teacher he influenced the training of physicians significantly.