Stress : What is it?

Stress : What is it? (27-Mar-2003)

Some definitions

Stress may be defined as a phenomenon which occurs when there is a perceived mismatch between the demands of a situation and our ability to cope with it.
The stress response is the way that we react to that stress: this may be a physiological, behavioural or psychological response.
A stressor is something that causes stress

Physiological response to stress

It is argued that our ancestors evolved the ability to react to threatening situations (e.g. the famous sabre-toothed tiger), in such a way as to prepare them for "fight or flight", by certain physiological changes that take place as soon as the threat is perceived.

The "fight or flight" response is governed by the Autonomic Nervous System (ANS), which controls bodily functions that we are not normally conscious of (e.g. breathing). The ANS has two components:

Sympathetic Nervous System (SNS). The SNS deals with stressful situations by causing the release of such substances as adrenaline, which gear up the body for "fight or flight".
Parasympathetic Nervous System (PNS). The PNS acts in opposition to the SNS, tending to calm the body down and restore activity to pre-stress levels.

General Adaptation Syndrome

Hans Selye was conducting research using rats and saw that they reacted in a similar way to any number of different stressors. Selye argued that there is a single physiological response to stress whatever the stressor is. Studies of human patients in hospitals seemed to lend support for this argument.

Selye called this response the General Adaptation Syndrome (GAS)). This is defined as having three stages:

Alarm. This is the fight/flight stage when the body is ready for action.
Resistance. Here, the body starts to resist the initial stressor. If a new stressor appears at this stage though, the body is less able to cope with it, and so is more susceptible to injury
Exhaustion. This is caused by chronic stress, or repeated new stressors. Here, the body's resources become exhausted and resistance is no longer possible. There is minimal resistance to disease, and so the body is more susceptible to illnesses (colds, infections, ulcers, heart disease etc.).

Strengths of Selye's GAS:

Inspired research
Provides explanation of why stress may be related to physical disease

Weaknesses:

Difficult to standardise what is a "stressor" - any given situation might result in different levels of stress to different individuals, and different stressors might cause different levels of stress to a single individual
Doesn't take into account psychological aspect - different people may have characters that are able to cope better or worse with stress

Stress and Illness

There are three ways in which stress may be related to illness:

Direct effect : chronic stress causes phsyical changes in the body which can lead to diseases such as coronary heart disease (CHD)
Interaction with vulnerability : people with a predisposition to high blood pressure are likely to be more badly affected by stress
Behavioural changes : people may react to stress by indulging in harmful bbehaviour (e.g. smoking, drinking)

Russek (1962) investigated the link between occupational stress and CHD, and found that workers in "high stress" jobs had a higher incidence of CHD than workers in "low stress" jobs.

Friedman and Rosenman (1974) tried to correlate personality type with CHD, and in a study of 3000 men over nine years, found that 70% of the deaths due to CHD were in the group of men termed "personality type A". In this study, "type A" men were characterised as "ambitious, time-conscious, driven", etc.. They concluded that people with this personality type are more likely to experience stress and therefore suffer from stress-related illness.

Friedman and Rosenman's conclusion has been challenged: for example, it may be that the "type A" characteristics are found in men who are more likely to smoke and drink. Johnstone (1987) conducted a study with 6,000 UK males over a period of six years and found no correlation between CHD and type A personalities.

It could also be argued that classification based on "hostility", "time-conscious", "competetive" is over complicated. Dembroski & Costa thought that the signficiant factor is "hostility". On the other hand, categorising people as one of "A/B/C" types is perhaps too simplistic, since people behave differently in different situations, and so one person may exhibit A,B or C type traits.

Although F+R argued that type A behaviour causes CHD, it would be that the type A behaviour was a result of the CHD (e.g. worried about CHD so become more stressed).

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