What Is General Adaptation Syndrome (GAS)?
The stages the body goes through in response to stress
Medically reviewed by Adjoa Smalls-Mantey, MD, DPhil
General adaptation syndrome (GAS) describes the physiologic changes your body goes through as it responds to stress. These changes occur in stages:
An alarm reaction (also called fight-or-flight)
A resistance phase (in which your body recovers)
A period of exhaustion
Enduring stress has physical and mental effects on the body. And the more your body goes through the stages of general adaptation, the greater the risk of long-lasting negative effects.
This article will help you better understand GAS and how it is triggered to help you reduce your stress.
Verywell / Michela Buttignol
The 3 Stages of General Adaptation Syndrome
General adaptation syndrome was first described by Hans Selye in 1936, but it wasn't until the 1950s that his research defined the three stages of GAS:
Alarm reaction
Resistance
Exhaustion
Related: What Is Stress?
Alarm Reaction Stage
The alarm reaction stage of general adaptation syndrome is the body’s initial response to stress. The sympathetic nervous system is activated by the sudden release of hormones. You may better know this stage as the fight-or-flight response.
The sympathetic nervous system is a part of the autonomic nervous system, which regulates the functions of your heart, stomach, bladder, and intestines, as well as your muscles. You are not aware that this system is working because it automatically responds to stimuli.
When the sympathetic nervous system is activated, it stimulates the adrenal glands. The glands, in turn, trigger the release of certain hormones, including adrenaline and noradrenaline.
The hormone release causes physical symptoms, such as increased heart rate, breathing rate, and blood pressure.
Takeaway
Physical signs of being in the alarm response stage include:
Dilated pupils
Increased heart rate
Rapid breathing
Trembling
Pale or flushed skin
Heightened senses
According to Selye, most of the symptoms of the alarm response stage disappear or are reversed in the next stage (resistance), then reappear in the final stage of exhaustion.
Resistance Stage
The resistance stage of general adaptation syndrome is when your body tries to repair itself after the initial shock of stress. If the stressful situation is no longer present and you can overcome the stress, your heart rate and blood pressure will start to return to prestress levels during this stage.
However, if the stressful situation continues for a long time or if you do not resolve the stress, your body will never receive a clear signal to return to normal functioning levels. This means it will continue to secrete the stress hormones and your blood pressure will stay high.
Related: What Research Says About Stress and Your Health
Prolonged levels of high stress can cause disturbances in the immune, digestive, cardiovascular, sleep, and reproductive systems. You might have symptoms such as:
Feelings of fear, anger, sadness, worry, numbness, or frustration
Irritability
Changes in appetite, energy, desires, and interests
Stomach problems
Headaches
Body pains or skin rashes
Sleeplessness or nightmares
Trouble concentrating or making decisions
Prolonged stress that is not resolved leads to the third stage (exhaustion).
Exhaustion Stage
Prolonged or chronic stress leads to the last stage of general adaptation syndrome—exhaustion. Enduring stressors without relief drains your physical, emotional, and mental resources to the point where your body is no longer able to cope with stress.
Signs that you are in the exhaustion stage include:
Fatigue
Decreased stress tolerance
Takeaway
The physical effects of prolonged stress can weaken your immune system and increase your risk of heart disease, high blood pressure, diabetes, and other chronic health conditions, including mental health disorders such as depression or anxiety.
Related: How to Manage Stress
Example of General Adaptation Syndrome
Here is an example of an event that might trigger general adaptation syndrome and possible ways you might experience each stage:
Alarm reaction: You have trembling hands and butterflies in your stomach prior to the start of an important exam.
Resistance: You've finished your exam but you're having trouble switching gears and focusing on other things.
Exhaustion: Your exam is in the past but you still feel anxious and depressed. You're having trouble sleeping and you wonder how you're going to get through the rest of the semester.
What Causes General Adaptation Syndrome?
Any kind of stressor—both unpleasant and rewarding, dangerous or thrilling—can trigger general adaptation syndrome.
Selye discovered general adaptation syndrome after studying how the human body reacted to physical stressors, such as being exposed to cold temperatures or physical overexertion.
It is now understood that many situations, including those that cause psychological rather than physical stress, can cause GAS.
Examples of stressors that can trigger GAS include:
Daily stress (such as pressure at school, work, or at home relating to your family)
A sudden change in your life (such as losing a job, divorce, or illness)
Traumatic experiences (such as abuse, a major accident, and war)
Positive Stress
General adaptation syndrome is not only triggered by stressors that cause distress. It can also be triggered by situations in which the stressor is considered positive or pleasant (known as eustress).
For example, some people see the stress of an upcoming exam as positive because it helps them to stay motivated. Others might enjoy the fear they feel while watching a scary movie.
Takeaway
What seems like a threat to one person might be perceived as a positive challenge to someone else. Their stress response to the same stimulus, therefore, will be different.
Related: How to Cope With Different Types of Stress
Conditions Associated With General Adaptation Syndrome
General adaptation syndrome is not a medical condition that you can be diagnosed with. Rather, it's the process your body goes through automatically when it experiences stress.
However, if you are experiencing chronic stress that is negatively affecting your life, it's important that you get help.
Physical conditions that may be triggered by long-term stress include:
Arthritis
Headaches
Heart disease
Heart attack
Hypertension
Inflammatory bowel disease (IBD)
Insomnia
Memory impairment
Metabolic syndrome
Muscle tension
Obesity
Pain
Peptic ulcer
Pregnancy complications, such as small birth weight and preterm labor
Stroke
Type 2 diabetes
Mental health conditions that have symptoms related to experiencing stress over extended periods include:
Anxiety disorders (e.g., generalized anxiety disorder, panic disorder, and phobia-related disorders)
Depression
Chronic stress is also associated with addiction to harmful substances and behaviors, including:
Alcohol
Food
Gambling
Illegal drugs
Internet
Nicotine
Prescription medications
Pornography
Sex
Related: How Prolonged Stress Impacts Your Health
Managing Stress
Stress mitigation techniques can help you cope with GAS. Examples you might want to explore include:
Limiting exposure to triggers
Takeaway
Anyone can become overwhelmed by stress. If you or a loved one are struggling, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 800-662-4357 for information on support and treatment facilities in your area. For more mental health resources, see our National Helpline Database.
Summary
General adaptation syndrome (GAS) describes the process your body goes through when you are exposed to any kind of stress, positive or negative. It has three stages: alarm, resistance, and exhaustion. If you do not resolve the stress that has triggered GAS, it can lead to physical and mental health problems.
Understanding which stressors affect you and learning strategies to cope with stress can help you avoid the consequences of chronic stress. If you are having a hard time coping with stress, reach out to a healthcare provider or mental health professional for support.
Related: Is Stress Ever Good for You?
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