An acute time-limited stressor involves a short-term challenge, while a brief  natural stressor involves an event that is normal but nevertheless challenging. A stressful event sequence is a stressor that occurs, and then continues to yield stress into the immediate future. A chronic stressor involves exposure to a long-term stressor, and a distant stressor is a stressor that is not immediate. Psychology
Acute stressful situations where the stress experienced is severe is a cause of change psychologically to the detriment of the well-being of the individual, such that symptomatic derealization and depersonalization, and anxiety and hyperarousal, are experienced. The International Classification of Diseases includes a group of mental and behavioral disorders which have their aetiology in reaction to severe stress and the consequent adaptive response. Chronic stress, and a lack of coping resources available, or used by an individual, can often lead to the development of psychological issues such as delusions, depression and anxiety (see below for further information).Chronic stressors may not be as intense as acute stressors such as natural disaster or a major accident, but persist over longer periods of time, tend to have a more negative effect on health because they are sustained and thus require the bodys physiological response to occur daily. This depletes the bodys energy more quickly and usually occurs over long periods of time, especially when these microstressors cannot be avoided (i.e. stress of living in a dangerous neighborhood). See allostatic load for further discussion of the biological process by which chronic stress may affect the body.
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.