AP Syllabus focus:
‘The general adaptation syndrome includes alarm, resistance, and exhaustion; illness risk is greatest during the exhaustion phase.’
General Adaptation Syndrome (GAS) is a classic model describing how the body responds to prolonged stress over time.
This graph visualizes Selye’s General Adaptation Syndrome as changes in stress resistance over time. It shows an initial dip during the alarm reaction, a sustained period of elevated resistance, and a later decline into exhaustion as physiological resources become depleted. The dashed baseline helps clarify that “adaptation” can temporarily exceed normal functioning but is not indefinitely sustainable. Source
It emphasizes predictable stages of physiological arousal and breakdown when stressors persist without adequate recovery.
Overview of General Adaptation Syndrome (GAS)
This diagram summarizes the three-stage progression of the General Adaptation Syndrome: alarm, resistance, and exhaustion. It emphasizes the time course of stress responding, highlighting how prolonged exposure can shift the body from short-term mobilization to long-term wear and eventual depletion. Used alongside the definition, it supports rapid retrieval practice of stage names and sequence. Source
Hans Selye proposed GAS to explain a general, predictable pattern in the body’s physiological response to sustained stressors (not just a single, brief threat).
General adaptation syndrome (GAS): A three-stage pattern of physiological responding to stress—alarm, resistance, and exhaustion—showing how the body initially mobilises, then copes, and may eventually break down.
GAS is especially useful for understanding why chronic stress (long-lasting or repeatedly triggered stress) can contribute to physical illness: the body’s stress systems are adaptive short-term but costly when activated too long.
Core idea: adaptation has limits
In the short run, stress responses help you meet demands (mobilizing energy and attention).
Over time, continued activation can strain body systems (e.g., cardiovascular and immune functioning).
The model’s final stage, exhaustion, highlights when the body’s capacity to maintain stress responding is depleted.
Stage 1: Alarm
The alarm stage is the body’s immediate reaction to a stressor—rapid mobilization of resources to confront or escape a challenge.
What happens in the alarm stage
The body detects a stressor and quickly increases physiological arousal.
Sympathetic nervous system activation supports rapid responding (increased heart rate and breathing).
Stress hormones (commonly associated with adrenal activity) help provide immediate energy and alertness.
Functional purpose
Prepares the organism for immediate action.
Enhances short-term performance for tasks requiring speed, vigilance, or physical effort.
Costs if frequently triggered
Repeated alarm responses can contribute to “wear and tear,” especially if the stressor is frequent and recovery time is limited.
Stage 2: Resistance
In the resistance stage, the body attempts to cope with the stressor for an extended period. Arousal may look “manageable” externally, but internal resources are being used to maintain functioning.
What happens in the resistance stage
Physiological systems remain activated enough to deal with the stressor.
The body reallocates energy to keep you functioning under continued demand.
Some restorative processes may be dialed down to prioritize coping (a key reason long-term stress can affect health).
What resistance can look like psychologically and physically
Appearing “fine” while feeling persistently tense or pressured.
Sustained effort, irritability, sleep disruption, or difficulty concentrating.
Increased vulnerability to stress-related physical complaints as the body stays activated.
Why resistance matters
This stage explains how people can endure ongoing stress for weeks or months, but often at an accumulating physiological cost.
Stage 3: Exhaustion
The exhaustion stage occurs when the stressor persists and the body can no longer maintain resistance effectively. Physiological resources are depleted, and functioning becomes harder to sustain.
What happens in exhaustion
The body’s ability to regulate and sustain stress responding weakens.
Fatigue, burnout-like symptoms, and reduced stress tolerance become more likely.
Systems strained during prolonged resistance may show breakdown or dysregulation.
Illness risk is greatest during exhaustion
A central AP point is that illness risk is greatest during the exhaustion phase because prolonged physiological activation can undermine the body’s maintenance functions, including processes important for physical resilience.
Key implications for health and wellness
Duration matters more than intensity alone
Brief stress can be adaptive, but long duration increases the chance of reaching exhaustion.
Frequent stressors can mimic chronic stress if recovery is incomplete between episodes.
Recovery interrupts the progression
Rest, sleep, and reduced demand can help prevent movement from resistance into exhaustion.
Without recovery, stress physiology can remain engaged long enough to increase vulnerability to stress-related illness.
FAQ
Selye’s early work relied heavily on animal studies, especially rats exposed to different stressors.
He argued the body showed a similar “general” physiological pattern across many stressors, supporting the idea of a non-specific stress response.
GAS can underemphasise psychological factors, such as how someone interprets a stressor.
It may also oversimplify stress patterns; real stress responses can be irregular, and people can show different trajectories depending on context and biology.
Yes. In real life, stressors often come in waves.
New stressors can retrigger alarm-like responses, and periods of partial recovery can shift someone away from exhaustion even if stress returns later.
They overlap conceptually but are not identical.
“Burnout” is typically used for work/role-related chronic stress and includes emotional and motivational components, whereas GAS exhaustion is a broad physiological endpoint in the model.
No. GAS describes a general pattern, not identical responses.
Individual differences (genetics, health status, sleep, and prior stress exposure) can affect how quickly someone progresses through stages and how strongly illness vulnerability appears.
Practice Questions
Outline the three stages of the general adaptation syndrome. (3 marks)
1 mark: Identifies alarm as the initial physiological reaction to a stressor.
1 mark: Identifies resistance as sustained coping/continued physiological activation.
1 mark: Identifies exhaustion as resource depletion/breakdown after prolonged stress.
A student experiences months of ongoing academic pressure and little sleep. Using the general adaptation syndrome, explain how the student’s response may change over time and why illness risk increases. (6 marks)
1 mark: Applies alarm to the initial stress response (heightened arousal).
1 mark: Applies resistance to continued demands (ongoing activation to cope).
1 mark: Applies exhaustion to prolonged stress (resources depleted).
1 mark: States illness risk is greatest in exhaustion.
1 mark: Explains increased illness risk via reduced capacity to maintain normal bodily functions after prolonged activation.
1 mark: Links the scenario detail (months/little sleep) to reduced recovery, increasing likelihood of exhaustion.
