The generality of the stress response (it is the same for a variety of stressors) was first appreciated about 70 years back by one of the pioneers of the field of stress physiology (Hans Selye). It can be said that the field was born because Selye was a very insightful scientist but very clumsy at handling laboratory rats. His fascinating story starts in the 1930s when lie was just beginning his work on endocrinology (study of hormones). As a young assistant professor he was looking for a promising area of research.
As luck would have it, a biochemist down the hall had just isolated some sort of extract I rom the ovary and everybody was wondering what the ex-tract did to the body. So, Selye obtained some of the stuff from the biochemist and set about his experiments. He attempted to inject his study rats daily but was very clumsy. He would drop them, chase them all over the laboratory and flail at them till he finally caught up with them.
Several months later, Selye examined the rats and discovered that they had peptic ulcers, greatly enlarged adrenal glands and shrunken immune tissues. Selye was delighted and thought that he had discovered the effects of the mysterious ovarian extract. Being a good scientist, he repeated his experiment with two groups of rats. One group received the extract and other received saline solution alone. His handling of the rats had not improved and all rats were dropped, chased, dropped and caught while receiving their injections.
At the end of the experiment, both groups exhibited the same symptoms—ulcers, enlarged adrenals and shrunken immune tissue. Faced with such a situation, the average scientist would have quietly burned his notes and slunk off to more promising fields like law or tried to get an MBA degree! Selye instead reasoned through what he had observed.
The extract could not cause the effects and the only thing common to both groups were the trauma-filled injections. He reasoned that the changes were the body’s response to generic unpleasantness. To test this idea, he put some rats on the top of the terrace in winter and some near the boiler in summer. In all cases, he found the same incidence of ulcer, and atrophy of the immune tissues.
We now know that Selye had observed the tip of the iceberg of stress-related disease. Legend has it (reading the literature it seems that this legend was mostly promulgated by Selye himself) that it was Selye who borrowed the term stress from the field of engineering. Selye was the first to theorize that—
• The body has a surprisingly similar set of responses to a broad array of stressors.
• Under certain conditions, stressors will make you sick.
In an interesting postscript to this story, Selye wrestled with the puzzle of why stress response makes us sick and came up with an answer. Unfortunately, his answer was sufficiently wrong that it is generally supposed to have cost him the Nobel Prize!
With the knowledge available now, it is pretty easy to see how turning on the stress response in the face of psychological stress can make us sick. The things that our body does in response to stress are generally shortsighted and inefficient.
They are the sort of costly things the body has to do to respond effectively in an emergency. If every day living becomes an emergency, you will eventually have to pay the price. If you constantly mobilize energy at the cost of its storage, you will never manage to have a surplus. You will fatigue more rapidly and run a high risk of developing diabetes. The consequences of chronically overactivating your cardiovascular system are similarly damaging.
Raising your blood pressure to 180/120 when sprinting for your life is being superbly adaptive but the same blood pressure in response to the mess in your children’s room will lead to disaster. In children, chronic stress can lead to a disorder called ‘stress dwarfism’. In females, chronic stress can lead to irregular menstrual cycles and, in males, sperm counts and testosterone levels may decline.
In both sexes, interest in sexual behaviour will decline and the immune system will be suppressed. But that is only the start of the problems—suppressing immune functions for too long can lead to other horrendous diseases (the tragedy of AIDS has taught us that lesson very well). Finally, the same systems of the brain that function so well during stress can be damaged by a class of hormones released during the stress response and can lead to neurological conditions like depression.