Quick answer
Stress triggers the fight-or-flight response: a surge of adrenaline and cortisol that raises heart rate and blood pressure, tenses muscles, sharpens the senses, and diverts energy to survival. Useful in short bursts — but when stress is chronic, that same response starts wearing the body down.
The immediate response
When your brain perceives a threat, it fires the fight-or-flight response almost instantly. Adrenaline surges, spiking heart rate and blood pressure to rush blood to the muscles; breathing quickens to grab more oxygen; muscles tense ready for action; senses sharpen; and cortisol releases stored energy while pausing 'non-essential' functions like digestion and, to a degree, immune activity. This is a brilliant survival system — it primes you to fight or flee a genuine danger, and it's meant to switch off once the threat passes, returning the body to normal.
When stress becomes chronic
The problem is that the modern stressors triggering this response — deadlines, conflicts, money, ongoing pressures — don't resolve in a burst of physical action, so the system stays switched on. Sustained, that takes a toll across the body: persistent muscle tension and headaches, ongoing digestive problems (the paused digestion becomes a chronic issue), disturbed sleep, and a suppressed immune system, so you get sick more easily. Over the long term, chronically raised blood pressure and stress hormones contribute to cardiovascular strain and other health risks. The survival response, run continuously, becomes corrosive.
Why this matters for anxiety
Understanding the body's stress response demystifies a lot of anxiety. The frightening physical symptoms of anxiety and panic — pounding heart, breathlessness, dizziness, tingling, nausea — are simply this fight-or-flight response firing, often without a real external threat. They feel dangerous but are the body doing exactly what it's designed to do; they're uncomfortable, not harmful. That knowledge is itself calming, and it points to the remedy: giving the body ways to discharge and recover from stress (movement, breathing, rest), and, for persistent anxiety, retraining the alarm system that's firing too readily.
When stress needs more than self-care
If stress has become constant, if your sleep, mood, or health are suffering, or if you can't switch off even when the pressure stops, it's worth talking to a professional. Chronic stress responds well to structured help, and getting support early prevents it from hardening into anxiety or burnout.
This article is for general information only and is not medical advice, diagnosis, or treatment. Always consult a qualified health professional about your situation. If you are in crisis, contact your local emergency number or a crisis line immediately.