The first link between long term stress and illness was discovered by Hans Selye in the 1930’s where he wrote about the General Adaptation Syndrome better known as G.A.S. His research came about by doing experiments on rats and seeing how they responded to different types of stress. He noticed that there was a pattern in the way in which the rats and hospital patients both reacted to stress. This is how the term G.A.S was introduced. Selye first started his research by exposing the rats to a variety of stressors including, bacterial infections, toxins, physical restraint and extreme temperatures. Selye’s definition of stress was “The non-specific response of the body to any demand made upon it”. This means that the body does not have a specific response to a particular stressor but that it has the same response for all stressors.
The stages of the G.A.S are alarm reaction, resistance and exhaustion. The alarm reaction stage is the ‘flight or fight’ response. This is acute stress where there is an increase activity in the sympathetic-adrenal-medullary system (SAM) and the hypothalamus-Pituitary-Adrenocorticol axis. The alarm stage can be recovered from quickly by dealing with the stressor therefore no damage has been done. The arousal of the Autonomic-nervous-system (ANS) releases adrenaline and noradrenaline which increases the heart rate and blood pressure as well as releasing blood sugar from the liver for physical activity, therefore swift action can be taken.
In the second stage a resistance to the stress is built up, if the stress is reduced, the rates of adrenaline and noradrenaline levels decrease at a steady rate, if the stress continues then the adrenal glands may be damaged. The person at this stage appears to be coping and is resisting to the stress however if another stressor is introduced then the person will over react even about a simple every day stressor such as losing your keys when in a hurry. Cortisol production is still increasing which can cause the production of white cells to be reduced consequently the immune system becomes weakened.
The final stage is exhaustion. This happens when stress is prolonged and the demands of the environment are too great to cope by the person. At this stage the person’s blood pressure and blood sugar rises and an increased risk of disease can occur. For example, depression, stomach ulcers and heart disease. This can cause the person to be hyperactive because of the increase in blood sugar and the best way to reduce this is to remove the stressor. Symptoms such as a raised heart beat and sweating may reappear from the ANS therefore the immune system may not be able to cope because the production of necessary proteins have been slowed down in favour of other needs to cope with the stress. Selye proved that the significance of the role of the HPA played an important part in long term stress and the link with physiological illness. As with any experiments there are always strengths and weaknesses.
The strengths of Selye’s experiment are that it was done under careful, scientific observation and it also generated a lot of other useful research. He was the first to identify a clear link between stress and illness some of the stressors including marital conflict, examinations, unemployment and bereavement have shown up in Selye’s experiments. The main theory has been proved correct that stress is linked with illness but as the theory is evaluated we can clearly see that there are more weaknesses to Selye’s theory than strengths. A major weakness is that he did not take into account the person’s own ability to cope therefore the stress levels would be different on different individuals. Selye said that there is no specific response to a particular stressor yet this can be argued with from evidence with anxiety which results in more adrenaline and more aggression results in more noradrenaline.
In addition to this Selye’s idea that stress always produced the same outcome was inaccurate as found out by a researcher named Mason who compared the responses caused by stress and found that the different stressors caused different levels or adrenaline, noradrenaline and Cortisol to be secreted in the body. These levels would be different in individuals therefore some stressors may affect one person more than another. It may be harder for one person more than another to cope with the stress or to create an adaptive response to reduce the stress therefore it building to long term stress. In addition to this, it does not take into account external help such as better resources for support and therefore the individual is able to cope better with the stress.
A big problem with Selye’s experiment was that he used rats to research how they would respond to the different stressors. Although this was more ethical than using humans it would not provide accurate results as rats and humans were two very different species, although mammals still have the same brain and nervous system structure. Humans could have been used; arguing that it was for medical purposes therefore was not unethical. In today’s times all animals are not allowed to be tested on although private clinics still experiment on animals as a means of producing results for problems like cancer, eye problems and skin problems. Many private clinics experiment on monkeys as they believe they are the closest animal to a human but we all know through Darwin’s theory of evolution that over time different animals have adapted to the environment in different ways some needing to more than others therefore results of animals compared to humans can provide no real evidence of the link between stress and physiological illness.
From the evaluation above the conclusion stands at although Selye’s experiment provides us with a detailed account of the link between long term stress and physiological effects it does not however take into account the individual differences and the different demands of the environment depending on where the individual lives. It also does not have a clear link of where the HPA takes over from the SAM system therefore it is difficult to show a clear level of what is a normal level of stress and what is not and if certain stressors cause a bigger illness such a heart disease or cancer that others. Research into the effects of physiological stress is difficult because we are all so different therefore a level of stress for one person may be too much or low for another person. Selye may have discovered a link between long term stress and illness but he did not evaluate the differences between the levels of hormones in the body of different people or the number of stress factors in a person’s life as well as how the individual copes or resists to the stressors.
