Stress is difficult to define because researchers approach it in different ways. Some use the term stress to refer to circumstances that threaten well-being or to refer to the response people have to threatening circumstances. Others think of stress as the process of evaluating and coping with threatening circumstances. Yet others use the term to refer to the experience of being threatened by taxing circumstances. This chapter will use the term stress in the last sense: the experience of being threatened by taxing circumstances.
Researchers agree that stress is subjective. People don’t have the same response to the same circumstances. Instead, stress depends on how people appraise or evaluate environmental events. If people believe that a challenge will severely tax or exceed their resources, they experience stress.
Stressors are psychologically or physically demanding events or circumstances. Research links stressors to increased susceptibility to physical illnesses such as heart disease as well as to psychological problems such as anxiety and depression.
Stressors don’t always increase the risk of illness. They tend to affect health more when they are chronic, highly disruptive, or perceived as uncontrollable. Researchers who study stress usually distinguish among three types of stressors: