Definition
The stress response is the body's integrated, full-system reaction to a perceived threat. The sympathetic nervous system fires within seconds — the familiar adrenaline surge — and the slower hormonal arm follows, releasing glucocorticoids over minutes. Together they redirect the body's resources toward immediate survival.
Sapolsky's central argument is that this system was built for short, sharp emergencies — a sprint from a predator — and excels at them. The trouble is that humans can summon the identical response by sitting still and worrying. A physiology tuned for minutes of crisis ends up running for months.
Why it matters
How it works
A threat — real or imagined — is appraised by the brain, especially the amygdala. That appraisal triggers the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis. Heart rate climbs, glucose floods the bloodstream, and non-urgent systems power down. When the threat passes, feedback loops should restore the resting state. Chronic stress keeps the appraisal switched on, so the body never fully stands down.