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The Centre for Studies on Human Stress (CSHS) is dedicated to improving the physical and mental health of Canadians by empowering individuals with scientifically grounded information on the effects of stress on the brain and body.
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History of stress

History of stress

The term stress was borrowed from the field of physics by one of the fathers of stress research Hans Selye. In physics, stress describes the force that produces strain on a physical body (i.e.: bending a piece of metal until it snaps occurs because of the force, or stress, exerted on it).

Hans Selye began using the term stress after completing his medical training at the University of Montreal in the 1920’s. He noticed that no matter what his hospitalized patients suffered from, they all had one thing in common. They all looked sick. In his view, they all were under physical stress.

He proposed that stress was a non-specific strain on the body caused by irregularities in normal body functions. This stress resulted in the release of stress hormones. He called this the “General Adaptation Syndrom” (a closer look at general adaptation syndrome, our body’s short-term and long-term reactions to stress).

The Great Debate

Selye pioneered the field of stress research and provided convincing arguments that stress impacted health. But not all agreed with his physiological view of stress as a non-specific phenomenon though. What about psychological stress?(i.e.: loss of the beloved, frustration, tending to an ill child, or work problems)? Could these situations also be stressful? Many physicians, psychologists, and researchers thought so.

A physician named John Mason conducted an experiment in which two groups of monkeys were deprived of food for a short period of time.

In group 1, monkeys were alone, while in group 2, monkeys watched others receive food. Even though both groups of monkeys were under the physical stress of hunger, those that saw others eat had higher stress hormone levels. He therefore showed that psychological stress was as powerful as physical stress at inducing the body’s stress response.

Many argued that if stress was a non-specific phenomenon then everyone should react the same way to the same stressors. BUT this did not seem right. Many were also convinced that there had to be common elements that would elevate everyone’s stress hormone levels.

In one interesting experiment, researchers measured the stress hormone levels of experienced parachute jumpers.

Jumping out of a plane surely had to be stressful! Strangely, their stress hormone levels were normal.

Stress hormone levels were then measured in both people jumping for the first time and their instructors. They found a big difference! On the day before the jump, student’s levels were normal while instructors’ levels were very high. On the jump day, students’ levels were very high, while instructor’s levels were normal.

They concluded that 24 hours before the jump, the instructors’ anticipation resulted in higher stress hormone levels because they knew what to expect. The students were oblivious!

But on jump day, the novelty and unpredictability of the situation made the students stress hormone levels sky rocket!

Over the next 30 years researchers conducted experiments showing that although the type of stressors resulting in the release of stress hormones are different for everyone there are common elements to situations that elevate stress hormones in everyone.

In essence, they discovered the recipe for stress: N.U.T.S.!



Threat to the ego

Sense of Control

Close-up on …The General Adaptation Syndrome

In Hans Selye’s theory, General Adaptation Syndrome had three stages.

Stage 1 : Alarm reaction

This is the immediate reaction to a stressor. In the initial phase of stress, humans exhibit a “fight or flight” response. This stage takes energy away from other systems (e.g. immune system) increasing our vulnerability to illness.

Did you know?

Hans Selye pioneered the field of stress research and provided arguments that stress impacted health.

Stage 2 : Resistance

If alarm reactions continue, the body begins getting used to being stressed. But this adaptation is not good for your health, since energy is concentrated on stress reactions.

Stage 3 : Exhaustion

This is the final stage after long-term exposure to a stressor. The body’s resistance to stress is gradually reduced and collapses as the immune system becomes ineffective. In Selye’s view, patients who experience long-term stress could succumb to heart attacks or severe infection due to their reduced resistance to illness.