Chronic stress

Chronic stress is the physiological or psychological response induced by a long-term internal or external stressor.^[1] The stressor, either physically present or recollected, will produce the same effect and trigger a chronic stress response.^[1] There is a wide range of chronic stressors, but most entail relatively prolonged problems, conflicts and threats that people encounter on a daily basis.^[2] Several chronic stressors have been identified as associated with disease and mortality including "neighbourhood environment, financial strain, interpersonal stress, work stress and caregiving."^[3]

Stress responses, such as the fight or flight response, is fundamental. The complexity of the environment means that it is constantly changing. To navigate the surroundings, we, therefore, need a system that is capable of responding to perceived threatening and harmful situations.^[4] The stress response system thus has its role as an adaptive process to restore homeostasis in the body by actively making changes.^[4][5] For instance, the body will involve in an endocrine system response in which corticosteroids are released. This process is known as allostasis, first proposed by Sterling and Eyer (1988).^[6] Research has provided considerable evidence to illustrate the stress response as a short-term adaptive system.^[4] The immediate effects of stress hormones are beneficial in a particular short-term situation. The system is arguably a protective defense against threats^[5] and usually does not pose a health risk.^[7]

However, the problem arises when there is a persistent threat. First-time exposure to a stressor will trigger an acute stress response in the body; however, repeated and continuous exposure causes the stressor to become chronic.^[4] McEwen and Stellar (1993) argued there is a "hidden cost of chronic stress to the body over long time periods".^[8] That is often known as allostatic load. Chronic stress can cause the allostasis system to overstimulate in response to the persistent threat.^[7] And such overstimulation can lead to an adverse impact. To illustrate, the long-term exposure to stress creates a high level of these hormones. This may lead to high blood pressure (and subsequently heart disease), damage to muscle tissue, inhibition of growth,^[9] and damage to mental health. Chronic stress also relates directly to the functionality and structure of the nervous system, thereby influencing affective and physiological responses to stress.^[3] These subsequently can result in damage to the body.