Introduction
Stress is the process by which a person perceives demands from the environment or from inside as exceeding their resources, and responds with physiological, emotional and behavioural changes. This topic covers the main theories of stress: the physiological model of Selye, the transactional model of Lazarus and Folkman, and the life-event approach. It also covers the body's stress systems, coping, and the effects of chronic stress on health.
Key concepts
- Stressor: the external or internal event or demand that triggers the response.
- Stress response: the physical, emotional and behavioural reaction to the stressor.
- Eustress and distress: stress that is motivating and manageable, versus stress that is harmful or overwhelming.
Physiological theory: Selye's general adaptation syndrome
Selye described a non-specific response of the body to any demand. The response has three stages:
- Alarm reaction: activation of the sympathetic nervous system and release of adrenaline and noradrenaline.
- Resistance: continued adaptation while the stressor persists, with cortisol release through the hypothalamic-pituitary-adrenal axis.
- Exhaustion: depletion of adaptive energy after prolonged stress, when disease and collapse of function become more likely.
The model explains why prolonged stress contributes to illness, but it does not explain why the same event affects people differently. This is the main limitation.