Stress - Introduction

Introduction

The stress response of the body is somewhat like an airplane readying for take-off. Virtually all systems (the heart and blood vessels, the immune system, the lungs, the digestive system, the sensory organs, and brain) are modified to meet the perceived danger.

External and Internal Stressors

People can experience either external or internal stressors.

• External stressors include adverse physical conditions (such as pain or hot or cold temperatures) or stressful psychological environments (such as poor working conditions or abusive relationships). Humans, like animals, can experience external stressors.
• Internal stressors can also be physical (infections, inflammation) or psychological. An example of an internal psychological stressor is intense worry about a harmful event that may or may not occur. As far as anyone can tell, internal psychological stressors are rare or absent in most animals except humans.

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Acute or Chronic Stress

Stressors can also be defined as short-term (acute) or long-term (chronic).

Acute Stress. Acute stress is the reaction to an immediate threat, commonly known as the fight or flight response. The threat can be any situation that is experienced, even subconsciously or falsely, as a danger.

Common acute stressors include:

• Noise (which can trigger a stress response even during sleep)
• Crowding
• Isolation
• Hunger
• Danger
• Infection
• High technology effects (playing video games, frequently ringing mobile phones)
• Imagining a threat or remembering a dangerous event

Under most circumstances, once the acute threat has passed, the response becomes inactivated and levels of stress hormones return to normal, a condition called the relaxation response.

Chronic Stress.Frequently, however, modern life poses ongoing stressful situations that are not short-lived. The urge to act (to fight or to flee) must therefore be controlled. Stress, then, becomes chronic.

Common chronic stressors include:

• On-going highly pressured work
• Long-term relationship problems
• Loneliness
• Persistent financial worries

Review Date: 10/25/2006
Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital