Psychological stress arises from the interaction between the individual and the environment. It is said to occur when environmental demands (stressors) exceed the individual’s capacity to deal with those demands (Lazarus and Folkman, 1984; Cohen et al., 1995). Stress is thought to exert its pathological effects on the body and increase the risk of disease in part by encouraging maladaptive behaviors as described above. People often cope with the negative emotions elicited by stress through behaviors that bring short-term relief but carry long-term risk. Under stress, people generally smoke more, drink more alcohol, eat foods with a higher fat and sugar content, and exercise less (Conway et al., 1981; Cohen and Williamson, 1988; Anderson et al., 1994). They also tend to have less and poorer-quality sleep (Akerstedt, 2006).
In addition, stress is thought to influence the pathogenesis or course of physical disease more directly by causing negative affective states, such as anxiety and depression, which in turn exert direct effects on biological processes that stimulate and dysregulate certain physiological systems in the body. The immune, cardiovascular, and neuro-endocrine systems are well-known respondents to stress (IOM, 2001). Long-term stressful circumstances that reduce perceptions of control and increase feelings of helplessness, hopelessness, and anxiety damage health and can lead to premature death, in part because of the immune, cardiac, and other physiological responses they produce (WHO, 2003). Individuals are even more vulnerable to the adverse physiological effects of stress when they are exacerbated by other psychosocial factors (e.g., a weak social network) or the individual has inadequate psychosocial assets to buffer the effects of exposure to stress.
There is strong evidence that chronic stress influences the development and/or progression of certain illnesses, including major depression, heart disease, HIV-related illnesses, and (to a lesser extent) cancer.
Substantial research links stressful life events to both diagnosed depression and depressive symptoms (Monroe and Simons, 1991; Kessler, 1997; Mazure, 1998; Hammen, 2005). One study found that during the 3–6