---
title: The Stress Response (archived)
url: https://mbmi.org/archive/mind-body-basics/stress/the-stress-response
description: The institute's explanation of the stress response as archived from mbmi.org: fight-or-flight, the hormones involved and why constant activation matters.
original_author: Mind/Body Medical Institute (later Benson-Henry Institute)
archived_at: https://web.archive.org/web/20081105090947/http://www.mbmi.org/basics/whatis_stress_response.asp
---
# The Stress Response (archived)

A short physiology primer on the body's automatic reaction to demands.

- Original author: Mind/Body Medical Institute (later Benson-Henry Institute)
- Original URL: http://www.mbmi.org/basics/whatis_stress_response.asp
- Captured: 2006-09-04 to 2008-11-05 (12 snapshots)
- Source: https://web.archive.org/web/20081105090947/http://www.mbmi.org/basics/whatis_stress_response.asp
- Current guide: https://mbmi.org/stress/effects

## What this page said

The page defined stress as the body's automatic physiological reaction to circumstances that require adjustment, also called the fight-or-flight response, first identified by Walter B. Cannon of Harvard Medical School nearly a century earlier. It said the hypothalamus triggers the sympathetic nervous system to release epinephrine and norepinephrine, which prepare the body to fight or flee whether the threat is physical or emotional, real or imagined.

It listed the effects: faster metabolism and heartbeat, tense muscles, shallow breathing and sweating, reduced blood flow to the internal organs and extremities, and inhibited immune and digestive function. The response is useful in an emergency, it said, but frequent or unrelenting activation without a balancing relaxation response can contribute to illness.

## Key points from the original

- Fight-or-flight was identified by Walter B. Cannon.
- Hormones involved: epinephrine and norepinephrine.
- Chronic activation without recovery was linked to illness.

This is a historical record, not medical advice.