general adaptation syndrome

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General Adaptation Syndrome



General adaptation syndrome, or GAS, is a term used to describe the body's short-term and long-term reactions to stress.
Stressors in humans include such physical stressors as starvation, being hit by a car, or suffering through severe weather. Additionally, humans can suffer such emotional or mental stressors as the loss of a loved one, the inability to solve a problem, or even having a difficult day at work.


Originally described by Hans Selye (1907–1982), an Austrian-born physician who emigrated to Canada in 1939, the general adaptation syndrome represents a three-stage reaction to stress. Selye explained his choice of terminology as follows: "I call this syndrome general because it is produced only by agents which have a general effect upon large portions of the body. I call it adaptive because it stimulates defense…. I call it a syndrome because its individual manifestations are coordinated and even partly dependent upon each other."
Selye thought that the general adaptation syndrome involved two major systems of the body, the nervous system and the endocrine (or hormonal) system. He then went on to outline what he considered as three distinctive stages in the syndrome's evolution. He called these stages the alarm reaction (AR), the stage of resistance (SR), and the stage of exhaustion (SE).

Stage 1: alarm reaction (ar)

The first stage of the general adaptation stage, the alarm reaction, is the immediate reaction to a stressor. In the initial phase of stress, humans exhibit a "fight or flight" response, which prepares the body for physical activity. However, this initial response can also decrease the effectiveness of the immune system, making persons more susceptible to illness during this phase.

Stage 2: stage of resistance (sr)

Stage 2 might also be named the stage of adaptation, instead of the stage of resistance. During this phase, if the stress continues, the body adapts to the stressors it is exposed to. Changes at many levels take place in order to reduce the effect of the stressor. For example, if the stressor is starvation (possibly due to anorexia), the person might experienced a reduced desire for physical activity to conserve energy, and the absorption of nutrients from food might be maximized.

Stage 3: stage of exhaustion (se)

At this stage, the stress has continued for some time. The body's resistance to the stress may gradually be reduced, or may collapse quickly. Generally, this means the immune system, and the body's ability to resist disease, may be almost totally eliminated. Patients who experience long-term stress may succumb to heart attacks or severe infection due to their reduced immunity. For example, a person with a stressful job may experience long-term stress that might lead to high blood pressure and an eventual heart attack.

Stress, a useful reaction?

The reader should note that Dr. Selye did not regard stress as a purely negative phenomenon; in fact, he frequently pointed out that stress is not only an inevitable part of life but results from intense joy or pleasure as well as fear or anxiety. "Stress is not even necessarily bad for you; it is also the spice of life, for any emotion, any activity, causes stress." Some later researchers have coined the term "eustress" or pleasant stress, to reflect the fact that such positive experiences as a job promotion, completing a degree or training program, marriage, travel, and many others are also stressful.
Selye also pointed out that human perception of and response to stress is highly individualized; a job or sport that one person finds anxiety-provoking or exhausting might be quite appealing and enjoyable to someone else. Looking at one's responses to specific stressors can contribute to better understanding of one's particular physical, emotional, and mental resources and limits.

Causes and symptoms

Stress is one cause of general adaptation syndrome. The results of unrelieved stress can manifest as fatigue, irritability, difficulty concentrating, and difficulty sleeping. Persons may also experience other symptoms that are signs of stress. Persons experiencing unusual symptoms, such as hair loss, without another medical explanation might consider stress as the cause.
The general adaptation syndrome is also influenced by such universal human variables as overall health and nutritional status, sex, age, ethnic or racial background, level of education, socioeconomic status (SES), genetic makeup, etc. Some of these variables are biologically based and difficult or impossible to change. For example, recent research indicates that men and women respond somewhat differently to stress, with women being more likely to use what is called the "tend and befriend" response rather than the classical "fight or flight" pattern. These researchers note that most of the early studies of the effects of stress on the body were conducted with only male subjects.
Selye's observation that people vary in their perceptions of stressors was reflected in his belief that the stressors themselves are less dangerous to health than people's maladaptive responses to them. He categorized certain diseases, ranging from cardiovascular disorders to inflammatory diseases and mental disorders as "diseases of adaptation," regarding them as "largely due to errors in our adaptaive response to stress" rather than the direct result of such outside factors as germs, toxic substances, etc.


GAS by itself is not an official diagnostic category but rather a descriptive term. A person who consults a doctor for a stress-related physical illness may be scheduled for blood or urine tests to measure the level of cortisol or other stress-related hormones in their body, or imaging studies to evaluate possible abnormalities in their endocrine glands if the doctor thinks that these tests may help to establish or confirm a diagnosis.
The American Psychiatric Association (APA) recognizes stress as a factor in anxiety disorders, particularly post-traumatic stress disorder (PTSD) and acute stress disorder (ASD). These two disorders are defined as symptomatic reactions to extreme traumatic stressors (war, natural or transportation disasters, criminal assault, abuse, hostage situations, etc.) and differ chiefly in the time frame in which the symptoms develop. The APA also has a diagnostic category of adjustment disorders, which are characterized either by excessive reactions to stressors within the normal range of experience (e.g. academic examinations, relationship breakups, being fired from a job) or by significant impairment in the person's occupational or social functioning.


Treatment of stress-related illnesses typically involves one or more stress reduction strategies. Stress reduction strategies generally fall into one of three categories: avoiding stressors; changing one's reaction to the stressor(s); or relieving stress after the reaction to the stressor(s). Many mainstream as well as complementary or alternative (CAM) strategies for stress reduction, such as exercising, listening to music, aromatherapy, and massage relieve stress after it occurs.
Many psychotherapeutic approaches attempt to modify the patient's reactions to stressors. These approaches often include an analysis of the patient's individual patterns of response to stress; for example, one commonly used set of categories describes people as "speed freaks," "worry warts," "cliff walkers," "loners," "basket cases," and "drifters." Each pattern has a recommended set of skills that the patient is encouraged to work on; for example, worry warts are advised to reframe their anxieties and then identify their core values and goals in order to take concrete action about their worries. In general, persons wishing to improve their management of stress should begin by consulting a medical professional with whom they feel comfortable to discuss which option, or combination of options, they can use.
Selye himself recommended an approach to stress that he described as "living wisely in accordance with natural laws." In his now-classic book The Stress of Life (1956), he discussed the following as important dimensions of living wisely:
  • Adopting an attitude of gratitude toward life rather than seeking revenge for injuries or slights.
  • Acting toward others from altruistic rather than self-centered motives.
  • Retaining a capacity for wonder and delight in the genuinely good and beautiful things in life.
  • Finding a purpose for one's life and expressing one's individuality in fulfilling that purpose.
  • Keeping a healthy sense of modesty about one's goals or achievements.



American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th ed., revised. Washington, D.C.: American Psychiatric Association, 2000.
Beers, Mark H., MD, and Robert Berkow, MD, editors. "Psychiatry in Medicine." Section 15, Chapter 1 85 In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.


Benton, Tami D., MD, and Jacqueline Lynch, MSW. "Adjustment Disorders." eMedicine September 3, 2004.
Cosen-Binker, L. I., M. G. Binker, G. Negri, and O. Tiscornia. "Influence of Stress in Acute Pancreatitis and Correlation with Stress-Induced Gastric Ulcer." Pancreatology 4 (July 2004): 470-484.
Motzer, S. A., and V. Hertig. "Stress, Stress Response, and Health." Nursing Clinics of North America 39 (March 2004): 1-17.
Yates, William R., MD. "Anxiety Disorders." eMedicine August 15, 2004.


American Institute of Stress. 124 Park Avenue, Yonkers, NY 10703 (914) 963-1200. Fax: (914) 965-6267.
American Psychiatric Association. 1400 K Street NW, Washington DC 20005. (888) 357-7924.
Canadian Institute of Stress/Hans Selye Foundation. Medcan Clinic Office, Suite 1500, 150 York Street, Toronto, Ontario, Canada M5H 3S5. (416) 236-4218.
National Institute of Mental Health (NIMH). 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 443-4513.


"Stress management, General adaptation syndrome, GAS …"

Key terms

Adjustment disorder — A disorder defined by the development of significant emotional or behavioral symptoms in response to a stressful event or series of events within the normal range of human experience.
Cortisol — A steroid hormone released by the cortex (outer portion) of the adrenal gland when a person is under stress.
Eustress — A term that is sometimes used to refer to positive stress.
Stress management — A set of techniques and programs intended to help people deal more effectively with stress in their lives by analyzing the specific stressors and taking positive actions to minimize their effects. Most stress management programs deal with job stress and workplace issues.
Stressor — A stimulus or event that provokes a stress response in an organism. Stressors can be categorized as acute or chronic, and as external or internal to the organism.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

general adaptation syndrome

all nonspecific systemic reactions of the body to prolonged systemic stress, including the alarm reaction, resistance, and exhaustion.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

gen·er·al ad·ap·ta·tion syn·drome

a syndrome introduced by Hans Selye to describe a single marked physiologic response in the pituitary-adrenal system, as a result of exposure to a variety of prolonged physical or psychological stresses or stressors, with the bodily changes progressing through three stages that the author described as the alarm reaction, resistance, and finally exhaustion. See: stress (4), stress (5). Compare: psychoendocrinology.
Farlex Partner Medical Dictionary © Farlex 2012

general adaptation syndrome

A nonspecific term for a suboptimal short- or long-term physiologic response to physical stimuli (e.g., trauma, hypothermia, starvation, infections, cardiovascular events) or emotional stressors (e.g., bereavement, divorce, loss of job, etc.). The original author of the GAS, Hans Selye, divided it into three stages:
(1) Alarm reaction—the fight or flight response;
(2) Stage of resistance or adaptation—physiologic responses to the stressors (e.g., reduced activity to conserve energy);
(3) Exhaustion stage or burn out, in which the immune systems lose all defensive capabilities, accompanied by multi-system shutdown.

Reduce stress.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

gen·er·al ad·ap·ta·tion syn·drome

(jen'ĕr-ăl ad'ap-tā'shŭn sin'drōm)
A term introduced by Hans Selye to describe marked physiologic changes in various organ systems of the body, especially the pituitary-endocrine system, as a result of exposure to prolonged physical or psychological stress.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

gen·er·al ad·ap·ta·tion syn·drome

(jen'ĕr-ăl ad'ap-tā'shŭn sin'drōm)
Syndrome with single marked physiologic response in the pituitary-adrenal system, due to exposure to a variety of prolonged physical or psychological stressors.
Synonym(s): adaptation syndrome of Selye.
Medical Dictionary for the Dental Professions © Farlex 2012