3 Stages of Stress: Alarm, Resistance & Exhaustion (2026)

The three stages of stress are the alarm stage, the resistance stage, and the exhaustion stage, first described by endocrinologist Hans Selye as the General Adaptation Syndrome. Every stress response you have, from a near-miss in traffic to months of financial pressure, moves through this same three-part sequence at different speeds and intensities.

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Selye developed this model after observing that laboratory rats exposed to different stressors, cold, injections, forced exercise, all showed the same pattern of physical changes. According to the American Psychological Association, roughly three in four U.S. adults report experiencing stress that affects their physical health, which makes understanding this sequence practically useful, not just academic.

This article walks through each stage in physiological detail: the specific hormones involved, how the HPA axis and SAM axis work together and separately, what distinguishes acute from chronic stress, how to tell which stage you’re currently in, and when moving through these stages repeatedly becomes a reason to talk with a healthcare provider.

What Are the 3 Stages of Stress?

The three stages of stress are alarm, resistance, and exhaustion, and together they describe how your body responds to any perceived threat over time.

Hans Selye proposed this model in 1936 after studying how organisms react to sustained physical stressors, later formalizing it as the General Adaptation Syndrome in 1950. Each stage reflects a different balance of hormone release, energy expenditure, and recovery capacity.

The alarm stage is the immediate, short-term reaction to a stressor, driven mainly by adrenaline and noradrenaline. The resistance stage follows as your body attempts to adapt and maintain functioning while the stressor continues. The exhaustion stage occurs only if the stressor persists long enough to deplete your physiological reserves.

One important note for people with generalized anxiety disorder: research indicates their baseline sympathetic activation often sits higher than average, so the alarm stage can trigger with less provocation than it would for someone without an anxiety disorder.

What Are the Three Stages of Stress?

The three stages of stress, alarm, resistance, and exhaustion, are not three separate events but one continuous physiological process that unfolds differently depending on how long a stressor lasts.

Think of it less like three doors you walk through and more like a dimmer switch. The alarm stage flips the switch fully on. The resistance stage tries to hold it at a manageable brightness while you keep functioning. The exhaustion stage is what happens when the switch has been on so long the bulb starts to burn out.

A single stressful event, a job interview, a close call while driving, typically only produces the alarm stage before your body returns to baseline. It’s ongoing or repeated stressors, an unstable job, a caregiving role, a chronic illness, that push the body into resistance and, eventually, exhaustion.

Quick Tip:

• The alarm stage is designed to be brief. If it becomes your near-constant state, that’s a signal the underlying stressor needs direct attention, not just symptom management.
• Resistance-stage functioning can feel deceptively “fine” even while cortisol stays elevated, which is why many people don’t notice chronic stress until the exhaustion stage.
• For adolescents, whose HPA axis reactivity is still maturing, the resistance stage may show up more as irritability or sleep disruption than as clear anxiety symptoms.

How Many Stages of Stress Are There?

There are three recognized stages of stress in Selye’s General Adaptation Syndrome model: alarm, resistance, and exhaustion.

This three-stage structure remains the most widely taught framework in physiology and psychology education, referenced by the National Institute of Mental Health and used across medical and clinical psychology training. Some later researchers have proposed additional nuance, including a “recovery” phase after exhaustion resolves, but the core model stays at three stages.

It’s worth being precise here because some non-clinical sources describe “four stages of stress” by splitting resistance into sub-phases or adding a burnout stage. That’s a reasonable elaboration for certain workplace-stress frameworks, but it is not the original or most commonly cited clinical model.

• Alarm: the fight-or-flight activation
• Resistance: the adaptation and coping phase
• Exhaustion: the depletion phase if stress continues unresolved

Older adults often show a blunted alarm-stage hormone spike compared with younger adults, according to research on age-related HPA axis changes, which can mean stress symptoms present more subtly and get missed longer.

What Is General Adaptation Syndrome?

General Adaptation Syndrome (GAS) is the physiological model, developed by Hans Selye, describing how the body responds to any stressor through the three sequential stages of alarm, resistance, and exhaustion.

Selye borrowed the term “stress” from engineering, where it describes the strain placed on a material, and applied it to biology after noticing that his lab rats developed the same triad of physical changes (enlarged adrenal glands, shrunken lymphatic tissue, and stomach ulcers) regardless of what specific stressor he used.

According to the American Institute of Stress, GAS remains foundational to how modern medicine and psychology conceptualize the difference between short-term adaptive stress and long-term maladaptive stress. It’s the reason clinicians distinguish “eustress,” stress that motivates and sharpens performance, from “distress,” stress that overwhelms coping capacity.

Evidence quality note: GAS is well-established as a foundational physiological framework confirmed by decades of endocrine research, though contemporary psychoneuroendocrinology treats it as a simplified model. Individual stress responses vary more than Selye’s original animal studies suggested, particularly based on psychological appraisal of the stressor, not just its physical intensity.

What Is the Alarm Stage of Stress?

The alarm stage of stress is the body’s immediate, short-term physiological reaction to a perceived threat, commonly known as the fight-or-flight response.

Within seconds of your brain’s amygdala registering a threat, the hypothalamus activates the SAM axis, triggering the adrenal medulla to release epinephrine and norepinephrine. Heart rate and blood pressure rise, pupils dilate, and blood flow shifts toward large muscle groups.

This stage is metabolically expensive but brief by design. Harvard Health Publishing describes this reaction as evolutionarily adaptive: useful for escaping genuine physical danger, but the same circuitry fires for a tense email or a missed deadline.

To recognize you’re in the alarm stage:

1. Notice a sudden increase in heart rate or a “jump” sensation right after a trigger.
2. Check for physical tightening: clenched jaw, shallow breathing, tense shoulders.
3. Watch for a brief spike in alertness or focus, sometimes described as tunnel vision.
4. Confirm the reaction fades within roughly 20 to 60 minutes once the trigger passes.
5. If it doesn’t fade, the body may be transitioning into the resistance stage instead.

Pregnant individuals experience heightened cardiovascular sensitivity during the alarm stage due to already-elevated baseline blood volume and heart rate, which is a reason obstetric providers often ask about stress levels at prenatal visits.

Key Takeaway: The alarm stage is your body’s adrenaline-driven emergency response, and it’s supposed to be short. If it doesn’t fade within an hour or two, your body is likely sliding into the resistance stage instead.

What Happens During the Resistance Stage of Stress?

During the resistance stage, the body attempts to adapt to an ongoing stressor by sustaining elevated cortisol output through the HPA axis while trying to maintain normal day-to-day functioning.

Once the initial adrenaline surge of the alarm stage settles, the hypothalamus releases corticotropin-releasing hormone (CRH), prompting the pituitary gland to release adrenocorticotropic hormone (ACTH), which signals the adrenal cortex to produce cortisol. This slower hormonal cascade is built for sustained, not momentary, demand.

A 2022 review published in Psychoneuroendocrinology describes this stage as a period of “allostatic adjustment,” where the body raises its operating baseline to cope with ongoing demand. That adjustment carries a cost, described in the research literature as allostatic load, the cumulative wear that sustained elevated cortisol places on the cardiovascular, metabolic, and immune systems.

Common resistance-stage signs:

• Poor concentration or a persistent sense of mental fog
• Irritability or a shortened fuse over minor frustrations
• Elevated blood pressure that a person may not notice without measurement
• Disrupted sleep, particularly trouble falling or staying asleep
• Digestive changes, including reflux or altered bowel habits

For people managing diabetes, sustained cortisol elevation during resistance-stage stress can measurably raise blood glucose, which is a specific reason endocrinologists ask diabetic patients about ongoing life stressors during routine visits.

What Is the Exhaustion Stage of Stress?

The exhaustion stage of stress occurs when a stressor continues long enough that the body’s hormonal and energy reserves used to sustain the resistance stage become depleted.

At this point, the systems that were compensating during resistance begin to falter. Cortisol regulation becomes dysfunctional, sometimes staying chronically elevated and sometimes blunting in a pattern researchers call hypocortisolism. The National Institute of Mental Health notes that prolonged HPA axis dysregulation is associated with several stress-related conditions, including major depressive episodes and generalized anxiety disorder, though it does not cause these conditions in every case.

Exhaustion-stage symptoms overlap significantly with burnout, which the World Health Organization’s ICD-11 classifies specifically as an occupational phenomenon rather than a medical diagnosis. That distinction matters: burnout describes a work-context pattern, while exhaustion-stage physiology can result from any chronic stressor, occupational or otherwise.

People with a personal or family history of depression appear to be at elevated risk of the exhaustion stage progressing into a depressive episode, based on observational research connecting chronic HPA axis dysregulation with mood disorder onset.

Key Takeaway: The exhaustion stage isn’t just “being really tired,” it reflects measurable depletion in immune and hormonal regulation, which is why it’s the stage most associated with getting sick more often and needing professional support.

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What Hormones Are Released During the Stages of Stress?

The stages of stress involve a specific sequence of hormones: epinephrine and norepinephrine dominate the alarm stage, while cortisol, released through the HPA axis, sustains the resistance and exhaustion stages.

Epinephrine (adrenaline) and norepinephrine (noradrenaline), released from the adrenal medulla within seconds of a perceived threat, raise heart rate, blood pressure, and glucose availability for immediate use. Cortisol, released more slowly from the adrenal cortex over 15 to 30 minutes, sustains elevated alertness and mobilizes stored energy for prolonged demand.

Two additional hormones play supporting roles. Aldosterone helps regulate blood pressure through sodium and fluid balance during sustained stress, and DHEA (dehydroepiandrosterone), also produced by the adrenal cortex, appears in some research to partially buffer cortisol’s negative effects, though evidence on DHEA supplementation for stress remains preliminary.

Evidence Quality Table:

Individuals on corticosteroid medications for conditions like asthma or autoimmune disease already have altered baseline cortisol regulation, which can blunt or exaggerate their natural stress hormone response depending on dose and timing, a detail worth mentioning to a prescribing physician.

What Is the Fight-or-Flight Response?

The fight-or-flight response is the alarm-stage activation of the sympathetic nervous system that prepares the body to either confront or escape a perceived threat.

The term, coined by physiologist Walter Cannon in 1915, describes the rapid, coordinated shift in which blood flow redirects toward skeletal muscles and away from digestive and reproductive functions, pupils dilate for wider peripheral vision, and the amygdala heightens threat detection while temporarily reducing input from the prefrontal cortex, the brain region responsible for measured decision-making.

That prefrontal cortex dampening explains a familiar experience: struggling to think clearly or make a calm decision in the middle of an acute stress reaction. It’s not a character flaw, it’s a temporary, mechanistic shift in blood flow and neural activity.

A less-discussed variant is the freeze response, in which the nervous system, rather than mobilizing toward fight or flight, temporarily immobilizes, a pattern more common in situations perceived as inescapable.

• Fight-or-flight raises heart rate and respiration within seconds
• It temporarily reduces digestive activity, which is why acute stress can cause stomach upset
• It sharpens sensory perception and reaction time for the immediate threat
• It reduces prefrontal cortex activity, affecting complex reasoning during the reaction itself

Trauma survivors, including people with PTSD, can experience fight-or-flight activation from cues that aren’t objectively dangerous but resemble a past traumatic context, a pattern well documented in trauma-focused clinical research and a reason exposure-based therapies are approached carefully by trained clinicians.

HPA Axis and the Stages of Stress

The HPA axis, short for hypothalamic-pituitary-adrenal axis, is the hormonal pathway primarily responsible for the resistance and exhaustion stages of the stress response.

Unlike the fast-acting SAM axis that drives the alarm stage, the HPA axis operates on a slower feedback loop. The hypothalamus releases CRH, which prompts the pituitary gland to release ACTH, which then signals the adrenal cortex to release cortisol. Cortisol itself eventually signals back to the hypothalamus and pituitary to reduce further CRH and ACTH output, a self-regulating loop called negative feedback.

Research published in the Journal of Clinical Endocrinology and Metabolism has repeatedly shown that when stress becomes chronic, this negative feedback loop can become less sensitive, allowing cortisol to remain elevated longer than it should. Over time, some individuals show the opposite pattern, a blunted cortisol response, which researchers associate with prolonged exhaustion-stage physiology.

Women during perimenopause often show altered HPA axis feedback sensitivity related to shifting estrogen levels, which several studies link to increased stress reactivity during this life stage, a detail rarely mentioned in general stress content.

Acute Stress vs. Chronic Stress

Acute stress is a short-term reaction confined mainly to the alarm stage, while chronic stress involves repeated or prolonged activation that pushes the body through resistance and potentially into exhaustion.

Acute stress, a near-collision, a surprising piece of news, a tight deadline, typically resolves within minutes to hours once the trigger passes, and the body returns to baseline without lasting physiological cost. According to the American Psychological Association, this type of stress, in moderate amounts, is not inherently harmful and may even support short-term performance and focus.

Chronic stress is different in kind, not just duration. It involves the HPA axis staying engaged for weeks or months, whether from ongoing life circumstances (a difficult job, caregiving demands, financial strain) or from a nervous system that doesn’t fully downshift between acute stressors.

People with existing cardiovascular disease face amplified risk from chronic-stress-pattern cortisol elevation, since sustained blood pressure increases compound existing cardiac strain, which is why cardiologists frequently screen for stress load in patients with hypertension.

Key Takeaway: A single stressful event rarely causes lasting harm, it’s the repetition and lack of recovery time between stressors that pushes the body from acute, manageable stress into the resistance and exhaustion stages.

Can You Skip Stages of Stress?

You cannot fully skip a stage of the stress response, but you can move through the alarm and resistance stages quickly enough that they resolve before reaching the exhaustion stage.

The three-stage sequence is physiologically fixed: the SAM axis alarm response always precedes HPA axis resistance activity. What varies enormously between individuals is how long someone stays in each stage and how effectively the body recovers between stressors.

This is where recovery capacity matters more than the stressor itself. Two people facing an identical stressor, say, a demanding work deadline, can have very different outcomes depending on baseline health, sleep quality, social support, and whether they’ve had recent unresolved stressors stacking on top of each other.

Quick Tip:

• Sleep quality is one of the strongest predictors of how quickly cortisol returns to baseline after the resistance stage.
• Repeated acute stressors without recovery time functionally behave like chronic stress, even if no single event lasts long.
• People with a diagnosed anxiety disorder often have measurably slower HPA axis recovery after a stressor resolves, based on research comparing cortisol return-to-baseline curves between clinical and non-clinical populations.

Is General Adaptation Syndrome Still Accurate?

General Adaptation Syndrome remains an accurate foundational framework for understanding the sequence of stress physiology, though modern research has refined and expanded parts of Selye’s original model.

Selye’s work, conducted primarily on rats between the 1930s and 1950s, focused on the body’s physical, hormonal response to stressors and largely didn’t account for psychological appraisal, the way an individual’s interpretation of an event shapes how intensely their body responds. Later researchers, notably Richard Lazarus and Susan Folkman’s transactional model of stress, added that a stressor’s impact depends heavily on how a person perceives their ability to cope with it.

Cleveland Clinic and Mayo Clinic both continue to reference the three-stage GAS framework in patient education material because it remains clinically useful for explaining why chronic stress produces physical symptoms, even though contemporary psychoneuroendocrinology treats individual variability, genetics, early-life stress exposure, and social context as equally important factors.

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• GAS accurately describes the general hormonal sequence: alarm, resistance, exhaustion
• It does not fully account for individual differences in threat appraisal
• It predates modern understanding of allostatic load and epigenetic stress effects
• It remains the standard teaching model in medical and psychology education

People who experienced significant early-life adversity show altered baseline HPA axis calibration in adulthood, according to research on early-life stress programming, meaning their alarm and resistance stages can activate at lower stress thresholds than the general population.

Signs You’ve Reached the Exhaustion Stage

Signs of the exhaustion stage include persistent fatigue not relieved by rest, increased frequency of minor illness, emotional flatness or low motivation, and difficulty concentrating that doesn’t improve with a night’s sleep.

Because exhaustion-stage physiology reflects genuine depletion of hormonal and immune reserves, its symptoms tend to be more pervasive and less responsive to short-term fixes than resistance-stage symptoms like irritability.

Physical and emotional signs to watch for:

• Getting sick more often than usual, including colds or cold sores, linked to reduced immune surveillance
• Persistent low mood or a flattened emotional range, distinct from situational sadness
• Sleep that doesn’t feel restorative even when duration is adequate
• Noticeable weight change without an intentional diet shift
• Loss of interest in activities that were previously enjoyable
• Increased reliance on caffeine, alcohol, or other substances to manage energy or mood

According to the National Institute of Mental Health, prolonged symptoms like these, especially when they persist for two weeks or longer and interfere with daily functioning, meet criteria worth discussing with a primary care physician, since they overlap significantly with early depressive symptoms.

Shift workers and new parents, both populations dealing with chronically disrupted sleep architecture, show exhaustion-stage symptoms earlier and more intensely than the general population in research on sleep-stress interaction, since sleep disruption independently impairs HPA axis recovery.

How to Manage Each Stage of Stress

Effective stress management is stage-specific: alarm-stage strategies focus on calming immediate physiological arousal, while resistance and exhaustion-stage strategies focus on reducing overall stressor load and restoring recovery capacity.

For the alarm stage, the goal is activating the parasympathetic nervous system to counteract the sympathetic surge. Diaphragmatic breathing, slow exhales longer than inhales, has strong evidence for rapidly lowering heart rate through vagus nerve stimulation.

For the resistance stage, the goal shifts to reducing total stressor load and supporting the HPA axis’s negative feedback loop. Cognitive behavioral therapy (CBT) has strong randomized-controlled-trial support for changing the appraisal patterns that keep the resistance stage engaged longer than necessary.

For the exhaustion stage, self-care alone is often not sufficient. This stage typically calls for combining lifestyle recovery (sleep prioritization, reduced stimulant use, gradual reintroduction of physical activity) with professional support, since depleted reserves take longer to rebuild and mood symptoms may need direct clinical attention.

To build a basic stage-appropriate response:

1. Identify which stage you’re likely in based on symptom duration and intensity.
2. In the alarm stage, use a 4-second inhale, 6-second exhale breathing pattern for two to three minutes.
3. In the resistance stage, identify and reduce one specific, modifiable stressor rather than trying to fix everything at once.
4. In the exhaustion stage, prioritize consistent sleep and consider scheduling a primary care visit.
5. Reassess weekly, since stage progression can move in either direction with the right recovery support.

People managing a chronic pain condition often find the resistance stage particularly persistent, since pain itself is a continuous physiological stressor, which is a specific reason pain management specialists frequently incorporate CBT or biofeedback into treatment plans.

Key Takeaway: The right stress management technique depends on which stage you’re in, breathing exercises calm the alarm stage fast, but exhaustion-stage recovery needs sustained sleep, reduced stressor load, and often professional support.

When Does Stress Become a Medical Concern?

Stress becomes a medical concern when exhaustion-stage symptoms persist for more than a few weeks, when new physical symptoms appear, or when mood changes begin interfering with daily functioning or relationships.

Certain presentations warrant prompt evaluation rather than continued self-management. Chest pain, unexplained shortness of breath, or symptoms resembling a heart attack should be evaluated immediately, since severe acute stress can, in rare cases, trigger Takotsubo syndrome, a temporary but serious stress-induced heart condition documented in cardiology research.

Warning signs that call for professional evaluation:

• Persistent low mood, hopelessness, or loss of interest lasting more than two weeks
• Physical symptoms like chest pain, heart palpitations, or severe headaches
• Significant, unintentional weight change
• Sleep disruption that doesn’t improve with basic sleep hygiene changes
• Increased use of alcohol or other substances to cope
• Difficulty functioning at work, school, or in relationships

A primary care physician is the appropriate first point of contact for physical symptoms or general evaluation, and can refer to a licensed clinical psychologist for CBT-based treatment or a board-certified psychiatrist if medication evaluation becomes appropriate. Bring a symptom timeline to that appointment, including when symptoms started, how they’ve changed, and any known stressors involved.

If you are in crisis or experiencing thoughts of self-harm, contact the 988 Suicide and Crisis Lifeline by calling or texting 988 at any time. This service is free, confidential, and available 24 hours a day.

Older adults with pre-existing cardiovascular disease should treat new chest symptoms during high-stress periods as urgent rather than assuming they’re purely stress-related, given the documented overlap between acute stress and cardiac events in this population.

Frequently Asked Questions About the 3 Stages of Stress

What are the three stages of stress called?

The three stages of stress are called alarm, resistance, and exhaustion.
They form Hans Selye’s General Adaptation Syndrome model.
Together, they describe how the body responds to a stressor from initial reaction through prolonged adaptation.

What is the first stage of stress?

The alarm stage is the first stage of stress.
It’s the immediate fight-or-flight reaction driven by epinephrine and norepinephrine.
This stage typically resolves within minutes to an hour once the stressor passes.

How long does each stage of stress last?

The alarm stage generally lasts minutes to about an hour.
The resistance stage can last hours to weeks depending on the stressor.
The exhaustion stage develops only if stress continues unresolved for weeks or longer, and duration varies significantly by individual.

Can you go through the stages of stress more than once?

Yes, the three stages repeat with every new stressor you encounter.
A person can cycle through alarm and resistance multiple times per day.
Reaching exhaustion typically requires sustained or repeated stress without adequate recovery time.

What stage of stress causes burnout?

Burnout is most closely associated with the exhaustion stage.
It reflects depleted hormonal, immune, and emotional reserves from prolonged stress exposure.
The World Health Organization classifies burnout specifically as an occupational phenomenon rather than a medical diagnosis.

Is the General Adaptation Syndrome model still used today?

Yes, General Adaptation Syndrome is still taught and referenced in medical and psychological education today.
It remains a foundational framework for understanding stress physiology.
Modern research has refined it by adding individual variation, psychological appraisal, and allostatic load concepts that Selye’s original model didn’t include.

The Bottom Line

Understanding which stage of stress you’re in changes what actually helps. A racing heart before a presentation calls for a few minutes of slow breathing, not a total life overhaul. A resistance stage that’s dragged on for weeks calls for identifying and reducing a specific stressor, not just powering through.

If you’re noticing exhaustion-stage signs, persistent fatigue, flattened mood, getting sick more often, that’s your body telling you its reserves are genuinely depleted. Start with sleep and one modifiable stressor, and loop in a primary care physician if symptoms stick around past a few weeks.

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You know your own baseline better than any framework does. Use these three stages as a map, not a diagnosis, and let your own symptom pattern guide when it’s time to bring in professional support.