He argued that all people have a natural urge and need to work for their own benefit, a message that found favor with industrialists and governments. He also coined the term stressor to refer to the causative event or stimulus, as opposed to the resulting state of stress. Selye was in contact with the tobacco industry from 1958 and they were undeclared allies in litigation and the promotion of the concept of stress, clouding the link between smoking and cancer, and portraying smoking as a "diversion", or in Selyes concept a "deviation", from environmental stress.From the late 1960s, academic psychologists started to adopt Selyes concept; they sought to quantify "life stress" by scoring "significant life events", and a large amount of research was undertaken to examine links between stress and disease of all kinds. By the late 1970s, stress had become the medical area of greatest concern to the general population, and more basic research was called for to better address the issue. There was also renewed laboratory research into the neuroendocrine, molecular, and immunological bases of stress, conceived as a useful heuristic not necessarily tied to Selyes original hypotheses. The US military became a key center of stress research, attempting to understand and reduce combat neurosis and psychiatric casualties.The psychiatric diagnosis post-traumatic stress disorder (PTSD) was coined in the mid-1970s, in part through the efforts of anti-Vietnam War activists and the Vietnam Veterans Against the War, and Chaim F. Shatan.
In biology, most biochemical processes strive to maintain equilibrium (homeostasis), a steady state that exists more as an ideal and less as an achievable condition. Environmental factors, internal or external stimuli, continually disrupt homeostasis; an organisms present condition is a state of constant flux moving about a homeostatic point that is that organisms optimal condition for living. Factors causing an organisms condition to diverge too far from homeostasis can be experienced as stress. A life-threatening situation such as a major physical trauma or prolonged starvation can greatly disrupt homeostasis. On the other hand, an organisms attempt at restoring conditions back to or near homeostasis, often consuming energy and natural resources, can also be interpreted as stress.The ambiguity in defining this phenomenon was first recognized by Hans Selye (1907–1982) in 1926. In 1951 a commentator loosely summarized Selyes view of stress as something that "...in addition to being itself, was also the cause of itself, and the result of itself".First to use the term in a biological context, Selye continued to define stress as "the non-specific response of the body to any demand placed upon it". Neuroscientists such as Bruce McEwen and Jaap Koolhaas believe that stress, based on years of empirical research, "should be restricted to conditions where an environmental demand exceeds the natural regulatory capacity of an organism".