The notion of “stress” is ingrained in our public discourse, creating a popular phenomenological term that is rarely defined. As accurately noted by Hans Selye, the founder of the term “stress” as we know it today, “everybody knows what stress is and nobody knows what it is”.

The term “stress” emerged out of the field of engineering to describe the actual physical strain put on a structure. In the mid-1930s, however, the paper “A Syndrome Produced by Diverse Nocuous Agents” was published in Nature, which would be the first paper to ever discuss stress. Written by Selye, the paper discussed experiments on rats who were given “acute non -specific nocuous agents”, or, stressors as we would call them today. The stressors given to the rats included exposure to cold, surgical injury, spinal shock, excessive muscular exercise, or sub-lethal drug administration. Through his investigation, Selye discovered that after a rat was exposed to a stressor, a typical “syndrome” appeared. What was strange about the “syndrome”, however, was that it was not at all related to the physical damage done by the stressor itself!

Selye noted that regardless of the type of stressor the rats were exposed to, two stages emerged immediately after being exposed to a stressor. In the first stage, 6–48 hours after the initial injury, amongst a myriad of symptoms, rats experienced a notable decrease in size of the thymus (the organ responsible for producing T cells, critical to immunity strategies). In the second stage, beginning at 48 hours after the initial injury, it seemed the brain structures responsible for the production of the organism’s growth stopped functioning in order to supply bodily resources where they would be more greatly needed, thus economizing the body’s resources. This work would be seminal in exploring the biomarkers of stress and provide a catalyst for stress research in general.

Emerging from this study, the stress response proposed suggested that three interdependent elements accompanied any specific stressor. In physiological terms, these were (1) hypertrophy in the adrenal cortex (essentially an enlargement in the structure of the brain which stimulates androgen glucocorticoid production – the hormones responsible for making sure our bodies stay in a normal state called “homeostasis”), (2) atrophy in the lymphatic system (responsible for the defense of the immune system), and (3) gastrointestinal ulcers.

In noting the abundant health issues derived from “stress”, Selye developed the General Adaptation Syndrome (GAS) Model, which suggested that the odd behavioral and physiological reactions to stress are caused by a disruption to the body’s homeostasis, or, in other words, the body’s natural balance. The GAS model accounts for three distinct phases that activate when we are under stress: the alarm reaction (made up of the “shock” and “anti-shock” phase), resistance stage, and exhaustion stage.

Within homeostasis, the body adapts to minor stressors, however when a stressor exceeds the amount of adaptation given in homeostasis, the body enters into the shock phase of the first stage, alarm, where cells in the hypothalamus structure of the brain begin to activate, the sympathetic nervous system (which regulates the body’s “sympathico-adrenal system”, otherwise known as the “fight or flight ” response) is suppressed. However, in the “anti-shock” phase, when the stressor persists, the sympathetic nervous system is activated, and the “fight or flight” reaction occurs in an attempt to best mobilize the body’s resources in case of danger primarily by releasing the stress hormone called “cortisol”.

It is in this “anti-shock” phase that the “stress” hormones rise and blood supply flushes to all vital organs to truly prepare the body to either fight the stressor or to flee: Pupils dilate and there is an increase in blood pressure, heart rate, perspiration and respiration. In this stage of stress a racing heart, chest pain, light headedness and muscle tremors, amongst other symptoms, are encountered. While in the short term, the release of cortisol is essential and valuable, but in excessive release, the hormone becomes maladaptive to the body.

If the stressor persists, the body goes into the second phase of GAS, “resistance”, where the body adapts to the stressor, but still maintains an increased level of cortisol to sustain alertness. The prolonged release of cortisol here begins to cause headaches, muscle spasms or even temporary paralysis. As the activation of the HPA axis and the subsequent release of cortisol is a demanding task, much of the body’s resources are now depleted.

If the stressor persists even further, the body enters into the final stage of the stress response, “exhaustion”. Here, the body is no longer able to resist the stressor. The body both physically and psychologically begins to damage itself, and illnesses can begin to form.

From a medical standpoint, according to The Wellness Book: The Comprehensive Guide to Maintaining Health and Treating Stress-Related Illness by Herbert Benson and Eileen Stuart, the manifestations of stress can cause or exacerbate a myriad of health issues including the following: allergic skin reactions, arthritis, constipation, cough, depression, diabetes, dizziness, headaches, heart problems such as angina, and even heart attack or cardiac arrhythmia, heartburn, hypertension, infectious diseases, such as colds or herpes , infertility, insomnia, irritable bowel syndrome, menopausal symptoms such as hot flashes, nausea, nervousness, pain of any sort, including backaches, headaches, abdominal pain, muscle pain, joint aches and chronic pain, slow wound healing, fatigue and ulcers.

Nevertheless, while stress may cause these ailments, the relaxation response can relieve them. Some of the most effective methods of relaxation, proven time and time again in the research literature is through cultivating mindfulness and practicing mindfulness-based meditation; exercising to boost endorphins and mood; and eating a wholesome diet.

By Mariana Bockarova