Hans Selye's General Adaptation Syndrome

We have all experienced stress, we have all waited for the dentist, on results day your hands might have been shaking when you opened the results' envelope...  When we get stressed, there is the physical response (hands shake, we sweat more, we feel the need to go to the toilet, etc.) and there is the psychological response...  You will probably know that this is often called the 'Fight or Flight response.  An important thing to know is that stress is the body's reaction to a stressor...

Hans Selye, in 1936, reported on an investigation into the effect of stress on rats.  He made them endure all kinds of stressors, he made them too hot; he made them too cold; he over-fed them; he under-fed them.  What he found was that no matter what the stressor was, the response to the stress was the same, and he described three stages:

The 'Alarm Reaction'...  This is the body's short-term response to a stressor.  It is equivalent to the 'fight or flight' response that was mentioned above...  When a threat is perceived, one of the changes in the body is that the Sympathetic Branch of the Autonomic Nervous System is activated which causes the release of adrenaline.  The action of Adrenaline may produce all or some of these effects: Increase in pulse and breathing rate; the skin may get flushed or go pale or may alternate between the two; digestion slows down or stops, which may be felt as 'butterflies'; the blood concentration of fats and sugars increases; blood supply to the muscles increases; salivation and tear production slows down, which may be felt as a dry mouth; there may be problem with vision which may be blurred or have 'tunnel vision'; there may be difficulty in hearing things; and reflexes are speedier than normal...  All of these responses have evolved to keep us safe, we either run away from a threat, e.g. a lion or bear, or we fight the threat...  People who have anxiety problems tend to see things as threats that are not threats...

the 'Stage of Resistance'...  This happens if the stress is maintained for a long time, and out-lasts the first stage.  Whereas the first stage primarily involved the nervous system, this stage primarily involves the hormonal system...  What happens here is that hormones, the 'stress hormones' i.e. glucocorticoids and cortisol, are released into the blood stream and increase the basal metabolic rate... A consequence of this increase is that the body's resources are depleted quicker, but the hormones have the effect of suppressing the immune response, making illness much more likely...

the 'Stage of Exhaustion'...  At this point, all the body's resources have been depleted, and there may be some interference with normal functioning.  If this stage is extended, it can result in illness, particularly cardio-vascular disease, some digestive problems are thought to be stress related, and some believe that cancer has a stress related component.  In Selye's rats, it resulted in many of the rats dying...

In 1975 Hans Selye extended his G.A.S. model and introduced the terms 'eustress' and 'distress'.  These terms are used to described the body's response to stress, but they are very different.  Eustress is 'good' stress, e.g. it is the stress that gets us up in the morning and doing the things that we need to do.  Weight Training is a form of eustress.  It generally refers to stress that has been resolved.  Distress, on the other hand, is stress that is not resolved and can lead to anxiety or depression or both.   It should be obvious that whether stress is experienced as eustress or distress depends not only on what the stressor is, but the individual's ability to cope with the stress.