Hans Selye (1907 - 1982), a Canadian physician, did much important theoretical work on the physical effects of stress. Some commentators considered him the first to demonstrate the existence of a separate stress disease, the stress syndrome, or General adaptation syndrome.

To grossly oversimplify to the point of circular argument, Selye discovered and documented that stress differs from other physical responses in that stress is stressful whether the one receives good or bad news, whether the impulse is positive or negative. He called negative stress distress and positive stress eustress.

Selye allegedly discovered the stress syndrome when in medical school he observed that people who had various illnesses seemed to share a quality of "sickness" that was highly similar.

He wrote Stress without Distress (1974) and The Stress of Life (1956). He worked as a professor and director of the Institute of Experimental Medicine and Surgery at the University of Montreal.

In 1968 he was made a Companion of the Order of Canada.