Stress is defined as an organism's total response to environmental demands or pressures. When stress was first studied in the 1950s, the term was used to denote both the causes and the experienced effects of these pressures. Since the 1990s, however, the word stressor has been used for a stimulus that provokes a stress response. One recurrent disagreement among researchers concerns the definition of stress in humans. The issue is whether it is primarily an external response that can be measured by changes in glandular secretions, skin reactions, and other physical functions—or if it is an internal interpretation of, or reaction to, a stressor, or both.
Stress in humans results from interactions between persons and their environment that are perceived as straining or exceeding their adaptive capacities and threatening their well-being. The element of perception indicates that human stress responses reflect differences in personality, as well as differences in physical strength or general health. Researchers have found that stressors can be:
sequential, such as events leading up to a job promotion or a move
intermittent, such as college exams
chronic, such as living with a life-threatening illness, being in an unhappy marriage, or living in poverty
Risk factors for stress-related illnesses are a mix of personal, interpersonal, and social variables. These factors include lack or loss of control over one's physical environment, and lack or loss of social support networks. People who are dependent on others (e.g., children or the elderly) or who are socially disadvantaged (i.e., because of race, gender, education level, or similar factors) are at greater risk of developing stress-related illnesses. Other risk factors include feelings of helplessness, hopelessness, extreme fear or anger, and cynicism or distrust of others.
Barbara M. Chandler, The Gale Group Inc., Gale, Detroit,