The General Adaptation Syndrome, or GAS, explains how the body responds to stress over time. This cheat sheet helps students connect psychological stress to physical reactions in the nervous and endocrine systems. It is useful for understanding health, behavior, motivation, and coping in everyday situations.
Students need this model to explain why short-term stress can help performance but long-term stress can harm health.
The GAS model has three stages: alarm, resistance, and exhaustion. During alarm, the body activates the sympathetic nervous system and releases stress hormones such as adrenaline and cortisol. During resistance, the body tries to adapt and keep functioning while stress continues.
During exhaustion, prolonged stress can drain resources and increase the risk of illness, burnout, and poor decision making.
Key Facts
- General Adaptation Syndrome = alarm stage + resistance stage + exhaustion stage.
- Alarm stage: the sympathetic nervous system activates the fight-or-flight response to prepare the body for immediate action.
- In the alarm stage, adrenaline increases heart rate, breathing rate, blood pressure, and blood glucose for quick energy.
- Resistance stage: cortisol helps the body maintain energy and stay alert while the stressor continues.
- Exhaustion stage: prolonged stress can weaken immune function, reduce concentration, and increase physical and emotional strain.
- Short-term stress can improve focus and performance, but chronic stress is linked to health problems when recovery is limited.
- Stress response pathway: stressor -> brain appraisal -> sympathetic nervous system and HPA axis activation -> hormone release -> body response.
- Effective coping can reduce the stress response by changing the stressor, changing the appraisal, or increasing recovery time.
Vocabulary
- Stress
- Stress is the physical and psychological response to a demand, threat, or challenge.
- Stressor
- A stressor is any event, situation, or thought that triggers a stress response.
- General Adaptation Syndrome
- General Adaptation Syndrome is Hans Selye's three-stage model of how the body responds to ongoing stress.
- Alarm Stage
- The alarm stage is the first GAS stage, when the body quickly prepares for fight or flight.
- Resistance Stage
- The resistance stage is the second GAS stage, when the body tries to adapt to a continuing stressor.
- Exhaustion Stage
- The exhaustion stage is the third GAS stage, when long-term stress depletes the body's resources and raises health risks.
Common Mistakes to Avoid
- Confusing stress with only negative events is wrong because stress can come from positive challenges, such as performing, competing, or starting something new.
- Mixing up alarm and resistance is wrong because alarm is the immediate fight-or-flight reaction, while resistance is the longer effort to cope with continuing stress.
- Assuming cortisol is always harmful is wrong because cortisol helps provide energy in the short term, but high levels over time can become damaging.
- Skipping the role of appraisal is wrong because the brain's interpretation of a situation affects whether it is experienced as stressful.
- Treating exhaustion as simple tiredness is wrong because the exhaustion stage can involve weakened immunity, emotional burnout, and reduced ability to function.
Practice Questions
- 1 A student gives a speech and notices a racing heart, sweaty hands, and faster breathing. Which GAS stage is most likely happening, and which hormone is strongly involved?
- 2 A person studies for 3 weeks while sleeping only 5 hours per night and begins getting sick often. Which GAS stage best explains this pattern?
- 3 List the three stages of General Adaptation Syndrome in order and give one body change or behavior linked to each stage.
- 4 Explain why two students can experience the same exam differently, with one feeling motivated and the other feeling overwhelmed.
Understanding Stress Response (GAS Model)
A stress response begins with interpretation, not simply with an event. Two students can face the same test, conflict, or crowded room and show different reactions. The brain quickly judges whether the situation seems dangerous, important, controllable, or uncertain.
The amygdala helps detect possible threat. The hypothalamus then helps coordinate body systems.
Fast nerve signals prepare the body within seconds. A slower hormone system, called the HPA axis, keeps the response going when the brain believes the demand has not ended.
Adrenaline and cortisol have different jobs and timing. Adrenaline acts quickly, making stored fuel available for muscles and sharpening attention toward urgent details. Cortisol rises more slowly and helps the body continue supplying energy.
Cortisol is not automatically harmful. It supports normal waking, energy use, and responses to real challenges. Problems develop when cortisol remains high too often or at the wrong times.
For example, stress late at night can make it harder to fall asleep. Poor sleep then makes the next day feel more threatening, creating a cycle.
The body can handle brief periods of high demand when recovery follows. The greater concern is allostatic load, meaning the wear created by repeated adjustment to stress. Constant deadlines, family conflict, money worries, illness, discrimination, or lack of sleep can keep the body prepared for action without enough time to reset.
This can show up as headaches, stomach discomfort, tense muscles, irritability, forgetfulness, or getting sick more often. These signs are real, though they do not prove that stress is the only cause. Health symptoms deserve attention from a trusted adult or health professional when they persist.
Students often meet this pattern during exam weeks, sports tryouts, performances, social pressure, or difficult home situations. A small amount of activation can help someone start work and notice important information. Too much activation narrows attention.
A student may focus only on the possibility of failure, misread a teacher's comment as criticism, or avoid starting an assignment. Avoidance can briefly reduce discomfort, but it may increase the problem later. Learning to notice early signs, such as racing thoughts or jaw tension, gives a person more choices before stress builds further.
Coping works best when it matches the source of stress. Practical coping includes making a study plan, asking for clarification, breaking a task into smaller parts, or getting help with a conflict. Cognitive coping means checking whether a fearful thought is fully supported by evidence.
Recovery coping includes sleep, regular meals, movement, quiet time, and supportive relationships. Slow breathing can help signal safety to the body by strengthening parasympathetic activity.
Coping does not mean pretending a serious problem is fine. It means reducing unnecessary strain while taking useful action and seeking support when the demand is too large to handle alone.