The General Adaptation Syndrome (GAS)
In order to develop a general theory for the physiological response of humans and animals to stress, Hans Selye, former director of Experimental Medicine and Surgery at the University of Montreal, performed an integrated analysis of the effects of stress on adrenal gland function. He called his model of stress adaptation the General Adaptation Syndrome or GAS. The GAS was thought by Selye to outline how the organism adapts physiologically to stressors in its attempt to restore homeostasis.
The GAS has proven useful for many years by providing a model of how stress-induced illness arises and by giving clinicians some insight into how to manage stress related conditions in their patients. According to Selye, there are three stages of stress response: alarm phase (acute stress); resistance phase (chronic stress); and exhaustion phase (burnout).
Stress includes not only psychological stress but also any insult to the body that may tax the adrenal gland function, including chronic infections, allergies, exposure to chemical toxins, use of stimulants (such as caffeine and nicotine), poor nutrition, physical trauma, and poor sleep habits, Other contributing factors include exogenous steroid use, chronic hypoglycemia, and pharmaceutical and non-pharmaceutical drug use. For instance, many people develop adrenal exhaustion after a physical trauma, such as a car accident, after an acute exposure to toxins in the workplace, or after an extended course of corticosteroid treatment.
Alarm Phase (Acute Stress)
The alarm phase of the GAS occurs when a stress is first encountered and an alarm is sounded in the body. This alarm, sometimes called the fight or flight response, is associated with an activation of the sympathetic nervous system.
Hormonally, we see