2011 Reprint of 1938 Edition. Full facsimile of the original edition, t reproduced with Optical Recognition Software. Illustrated with photographs demonstrating the techniques outlined. If anyone persists in reading this book, he is in danger of finding that he can sleep better, if he will practice what it preaches. For it has been shown in my laboratory that sleep can be cultivated. -from the Preface. Edmund Jacobson was an American physician in internal medicine and psychiatry and a physiologist. He was the founder of the Progressive Muscle Relaxation and of Biofeedback. Jacobson was able to prove the connection between excessive muscular tension and different disorders of body and psyche. He found out that tension and exertion was always accompanied by a shortening of the muscular fibers, 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.