Edmund Jacobson (April 22, 1888 – January 7, 1983) was an American physician in internal medicine and psychiatry and a physiologist.

[1] In 1921, he introduced the application of psychological principles to medical practice which was later called psychosomatic medicine.

Employing low microvoltage apparatus, Jacobson also made the first accurate electrical measurement of muscular tonus, nerve impulses and mental activities in neuromuscular sites in living men.

He found out that tension and exertion was always accompanied by a shortening of the muscular fibres, that the reduction of the muscular tonus decreased the activity of the central nervous system, that relaxation was the contrary of states of excitement and well suited for a general remedy and prophylaxis against psychosomatic disorders.

In 1929, after twenty years of research, Jacobson began to publish his results in the book Progressive Relaxation.