Stress is the body's way of responding to any kind of demand. This can be the bodies physical reactions to stress which can be measured, for example changes in hormones secretions, skin reactions, and other physical functions. It can also be defined by individual internal interpretation or individual reaction to a specific stressor (stimuli that cause stress). Dr Simon Green in 1994 said that "a state of stress exists when there is a discrepancy between the perceived demands on an organism and its perceived ability to cope."
Stress can be both good and bad for individuals and can be caused by both good and bad experiences. Individually a person reacts to external stimuli and their body reacts by releasing chemicals into the bloodstream. Early studies on stress (conducted by Walter Cannon in 1932) established the exsistence of the well documented 'fight or flight' response. Sudies show that when a person experiences a shock or perceives and threat/danger is their environment then the body releases hormones in response to that perception. This gives people more energy and strength by increasing the heart rate and blood pressure, delivering more oxygen and blood sugar to power important muscles. Blood is diverted away from the skin to the core of our bodies, reducing blood loss if we are damaged. And as well as this, these hormones focus our attention on the threat, to the exclusion of everything else. All of these changes significantly improves the ability to react and survive life-threatening events.
Unfortunately, the fight or flight response can be stimulated when faced with non life-threatening events and this can have negative consequences on individuals, especially if there is no outlet for the extra energy and strength that the body is faced with. Recent reseasch research shows that we experience the fight-or-flight response when simply encountering something unexpected. This rapid response put the body into a highly energised state and routine maintenance of the body is stopped to divert energy to dealing with the emergency. The sympathetic autonomic system (SAS) stimulates the neuroendocrine system to produce many hormones, the heart beats faster and blood pressure is raised and more sugar is released into the blood. The faster heart rate and increased sugar give the body more energy for extreme effort. In the fight or flight state individuals can be excitable, anxious, jumpy and irritable which can reduce our ability to function effectively. If the chemicals released during fight or flight (adrenaline) increases out heart and blood pressure individuals may find it difficult to execute precise, controlled skills and can interfere with making sound judgements. People in this state frequently or persistently may find thenselves more accident-prone and less able to make good decisions. This hormonal, fight-or-flight response is a normal part of everyday life and a part of everyday stress, although often with an intensity that is so low that we do not notice it.
Studies on stress by Dr Hans Seyle identified a further response known as the 'general adaptation syndrome' with which the body reacts to major stimulus in response to longer-term exposure to causes of stress. He believed that stress was a non-specific response, that is, the body responded in the same way to any stressful happening. Seyle's three stages of stress are: the alarm phase when reacting to the stressor, the resistance phase as we adapted to and cope with the stressor and once this resistance is exhausted the final exhaustion phase where resistance declines substantially (this is also known as burnout).
Stress is an individual interpretation to our environment and how stressed we feel comes from this. To be stressed one must feel threatened by a situation and secondly we must doubt our abili8ty to deal with a threat/perceived threat. Survival stress is a response to danger. When you are afraid or anxious of something or someone your body naturally reacts with the fight or flight response. However, this is open to interpretation by individuals. For example, in 1995 Tennes found that the stress hormone cortisol was raised in above intelligence children on days when they had a test but was not raised in below average children. This is probably because academic success was more important for children of above average intelligence.
Most stressors are subtle and occur without obvious threat to survival (fight or flight response). These are often termed emotional stress and can come from things like daily routines (work overload, conflicting priorities, travel problems) relationships (home, family and friends) etc. Stressors can also manfist over a longer period such a a sudden loss (grief), a major life changes, caring for someone or yourself having long term health problems. There is also a third rtype of stress which is internal, this is when people worry about things they cannot do anything about or people worrying for no reason at all or where people put themselves in situations they know to be stressful. Environmental stress is a response to things around you that can cause stress such as noise and crowding.
In 1975 studies by Mason produced a lot of evidence to show that the body responded in different ways to different stressors. For example, for some stressful events the body produced three important hormones and for others two. The reason for this difference is that some stressful events are more emotionally upsetting to individuals than others. However, this theory does not consider the many factors that influence the response to stress. For example it ignores individual differences in the stress response. In 1986, Kobasa's studied executives who were in highly stressful situations. Some felt stressed and developed physical illnesses, whereas others did not. The ones who didn't show symptoms of stress actually had a greater sense of control and commitment and perceive things as challenging rather than stressful.
Gender difference can also impact on stress reactions as studied bt Frankenhauser in 1991. For example, men release more adrenaline under stress and are at a higher risk of heart attack; or the difference may be their coping mechanisms. In 1996 Brannon reports that women's friendships are much more likely provide emothional support which helps women cope with stress better.
Occasional stress can increase productivity, be motivating and even improve performance for some. However, too much or prolonged stress is unhealthy and can cause physical symptoms such as:
lack of appetite
There are also more severe symptoms of stress that can lead to life threatening conditions; stress can lead to heat attacks. The physiological effects of stress stimulate the sympathetic branch of the autonomic nervous system which makes the heart beat faster and raises blood pressure. In addition, hormones that can damage the cardiovascular system are released. In 1974, Rahe completed a retrospective study on people who had sudden heart attacks. He found that those that died had suffered more life changes than those who did not have a fatal heart attack. However, retrospective studies rely on people's memories and can be unreliable. Rahe therefore carried out a further prospective study which also supported his previous theory that stressed people were more likely to have a heart attack.
In 1990 Karasek found that that having a demanding job was positively correlated with heart disease. The studies measured job demands (to how emotionally involving the job was and how skilled it was ) and job control (how much the workers could pace the flow of work).
However, Karasek's and Rahe's studies are correlational and from correlation you cannot infer causation. These isnore a large number of cariables that affect the stress response. Perhaps for some reason people who are overweight do not get high status jobs and so get jobs with high demands and low control. So the correlation between demanding jobs and heart attack would be due to overweight and not the job stress.
On balance, the evidence supports the idea that stress is bad for the heart. However, the theory tends to ignore individual differences and gender. Being stressed does not necessarily lead to a heart attack. It is also possible that the effect of stress are indirect; stressed people tend to smoke more, to take less exercise, and eat more junk food. All of these are risk factors that can lead to heart attack.
Stress can also have a detrimental impact on the body iummune system; the body's defence against disease. In 1975, Ader provided evidence that the immune system of rats can be affected by psychological events and so could be damaged by stress. However, these results cannot be generalised from rats to humans as the physiological systems may too different.
Due to the ethical problems of inducing stress on humans there have been natural experiments on humans which do not increase the stress levels but merely take advantage of a naturally occurring situations. In 1983, Jemmott took blood samples from students during examination periods which showed lower levels of antibodies in their blood during examinations thus proving the stress of the examinations had reduced the efficiency of their immune system.
These studies can be criticised as they does not show that damage to the human immune system definitively leads to illness. They just show that stress has been shown to reduce the level of immune functioning but not by a dangerous amount; the level of immune system functioning is still within the normal range for the control groups.
So to conclude, since stress lowers the body's immune system and the immune system is the body's defence against illness, it is likely that stress makes the person more liable to a variety of disorders..