Physiology of Stress and Effects on Health

The human body responds to stress through a complex interplay of physiological systems. The autonomic nervous system, responsible for involuntary functions like breathing and heart rate, is immediately activated during stressful situations. This system triggers the "fight or flight" response, preparing the body to confront or escape danger. The endocrine system, utilizing hormones for communication, plays a slower but equally crucial role. When faced with stress, the sympathetic nervous system sends signals to the endocrine glands, releasing hormones like adrenaline and cortisol that further mobilize the body's resources (Sapolsky, 2004).

While this physiological response is essential for survival in acute emergencies, chronic or prolonged stress can have detrimental effects on health. The sustained elevation of heart rate and blood pressure can contribute to hypertension and atherosclerosis, increasing the risk of cardiovascular diseases such as heart attacks. Additionally, stress can disrupt the normal functioning of the gastrointestinal system, leading to issues like gastric ulcers and irritable bowel syndrome (IBS) (Selye, 1956).

General Adaptation Syndrome (GAS)

Hans Selye's General Adaptation Syndrome (GAS) model provides a framework for understanding the relationship between prolonged stress and illness. This model outlines three distinct phases:

1. Alarm Reaction (Fight or Flight): This initial stage involves the activation of the sympathetic nervous system and the release of stress hormones, preparing the body for immediate action.
2. Resistance Stage: If the stressor persists, the body attempts to adapt and reduce arousal levels while still coping with the demanding situation. However, this sustained resistance comes at a physiological cost.
3. Exhaustion Stage: Prolonged exposure to the stressor eventually overwhelms the body's ability to cope. This stage is characterized by a breakdown of physiological systems, leading to increased vulnerability to physical and mental health problems.

The GAS model highlights that while short-term stress can be adaptive, chronic stress can lead to a cascade of negative health outcomes. Persistent high blood pressure, for instance, can increase the risk of stroke or myocardial infarction (heart attack). Even seemingly minor effects, such as stomach ulcers, underscore the pervasive impact of prolonged stress on the body (Selye, 1956).

Causes of Stress

Stressors, the triggers that elicit the stress response, can stem from various sources:

1. Work

Occupational stress is a significant contributor to overall stress levels. Factors such as high workload, lack of control, job insecurity, and poor work-life balance can all contribute to work-related stress. A longitudinal study by Chandola et al. (2008) involving over 10,000 London civil servants revealed a strong association between work stress and unhealthy lifestyle choices, including lack of exercise and poor diet. Moreover, the study found a higher prevalence of self-reported stress among individuals under 50 and a correlation between stress levels and the likelihood of coronary heart disease (CHD).

2. Life Events

Major life changes, both positive and negative, can also be significant sources of stress. The Social Readjustment Rating Scale (SRRS), developed by Holmes and Rahe (1967), quantifies stress levels associated with various life events. Events such as the death of a spouse, divorce, or job loss are assigned high scores, indicating greater stress levels. Research utilizing the SRRS has shown that individuals accumulating high scores within a year (over 300) are at an increased risk of experiencing stress-related illnesses.

3. Personality

Individual personality traits can also influence susceptibility to stress. Friedman and Rosenman's (1974) research identified a link between Type A personality characteristics and an increased risk of heart conditions. Type A individuals, characterized by traits like competitiveness, time urgency, and hostility, tend to experience higher levels of physiological stress. In contrast, those with Type B personalities, who are generally more relaxed and easygoing, have a lower risk of developing coronary problems.

Conclusion

The physiological response to stress is a complex and multifaceted process with significant implications for health. While the "fight or flight" response is crucial for survival in acute situations, chronic stress can have detrimental effects on various bodily systems. Understanding the causes of stress and their physiological consequences is essential for developing effective stress management strategies and promoting overall well-being.