The Intuition: Your Body's Alarm System
Think about the last time you had a genuinely stressful day — maybe an exam you hadn't prepared for, a sudden deadline, or a confrontation. Your heart pounded, your palms got sweaty, your breathing quickened. That's your body's emergency response kicking in. But what happens if that stress doesn't go away? What if the exam stress lasts for weeks, or the deadline keeps getting extended?
Your body can't stay in full emergency mode forever. It would exhaust itself. So it goes through a predictable three-stage process to cope with prolonged stress. That process is what Hans Selye called the General Adaptation Syndrome (GAS) .
The Precise Statement
General Adaptation Syndrome is a three-stage physiological response that the body undergoes when exposed to stress — any stress, whether physical (injury, cold), psychological (anxiety, pressure), or social (conflict). The three stages are:
- Alarm Reaction
- Resistance
- Exhaustion
Let's walk through each one.
Stage 1: Alarm Reaction
This is the immediate "fight-or-flight" response. When you first encounter a stressor, your hypothalamus activates the sympathetic nervous system. Adrenaline and noradrenaline surge. Your heart rate and blood pressure rise, pupils dilate, digestion slows, and blood is diverted to muscles.
This stage is actually split into two phases: shock (the initial dip in resistance as the body is caught off guard) and countershock (the rebound where the body mobilises its defences). In most exam contexts, you only need to remember the overall alarm reaction.
At this point, your resistance to the stressor is actually below normal for a brief moment (the shock phase), then shoots up above normal as the body fights back.
Stage 2: Resistance
If the stressor persists beyond the initial alarm, the body cannot maintain the full fight-or-flight state. It settles into a resistance stage. Here, the body adapts to the ongoing stressor. The initial dramatic symptoms (racing heart, sweating) subside. Hormone levels — particularly cortisol from the adrenal cortex — remain elevated, but the body appears to function normally.
During resistance, the body's resources are being diverted to cope with the stressor. This means resistance to other stressors drops. A student under chronic exam stress might catch a cold easily — not because the stressor (exams) directly causes it, but because the body has less capacity to fight off a new threat.
This stage can last for days, weeks, or even months. The body is essentially running on a "war economy" — it works, but at a cost.
Stage 3: Exhaustion
The body's resources are finite. If the stressor continues long enough, the body can no longer sustain the resistance stage. The elevated cortisol levels, the constant metabolic demand, the diverted energy — it all takes a toll. The body enters exhaustion.
In this stage, the body's ability to resist the stressor collapses. The symptoms of the alarm reaction may reappear, but now the body cannot mount an effective response. This is where stress-related illnesses emerge: ulcers, hypertension, weakened immune function, and in extreme cases, organ failure or death. …