Fight or Flight: How Stress Affects Health

The Design of Our Bodies to Deal with Stress

Our bodies are wonderfully designed to rise to daunting challenges - escaping from dangerous situations by fleeing or fighting an enemy; performing feats of strength that seem impossible such as carying an injured person from a burning building; having all senses on red alert when peak performance is required, such as in an athletic competition or dealing with complex, high-stakes situations.

The body, however, is not particularly good at distinguishing between true, life-threatening emergencies and the anxieties, worries, stresses and challenges of modern life. Whether the emergency is real or perceived, the body responds as if it were a life or death situation.

Post-Traumatic Stress Disorder

In working with persons suffering from Post-Traumatic Stress Disorder, I have frequently seen how even the memory of a very stressful event can trigger powerful physiological responses: sweating, trembling, increased heart rate and blood pressure, faster breathing, tingling, feelings of panic, heightened sensory awareness, and more. Clients have reported digestive and bowel disruption, feeling chilled, and sleep disruption.

Since World War I, scientists have studied in detail the responses the body makes to a perceived threat. This bodily response system is called the stress response, and it was first studied in soldiers responding to combat situations. Soon researchers such as Hans Selye came to see that the stress response may be generated in the body whether the threat is physical or psychological.

What Happens with a Stressful Event

Medical researchers have traced the stress response as it cascades throughout the body, affecting every system of the body. When the brain perceives threat or danger, the hypothalamus sends a signal to the pituitary gland, which releases adrenocorticotropic hormone (ACTH) which in turn signals the adrenal glands to spill cortisol, adrenaline and noradrenaline into the bloodstream. These are the so-called stress hormones, which have a powerful impact on the body, mobilizing it for fight or flight.

The Harvard Medical School Special Health Report on Stress Control summarizes what happens next:

Your breath quickens as your body takes in extra oxygen. Energy-boosting glucose and fats are released from storage sites into your bloodstream. Sharpened senses, such as sight and hearing, make you more alert.

Your heart beats faster - up to five times as quickly as normal - and your blood pressure rises. Certain blood vessels constrict, which helps direct blood flow to your muscles and brain and away from your skin and other organs.

Blood cells called platelets become stickier so clots can form more easily to keep you from bleeding to death from potential injuries. Immune system activity picks up. Your muscles - even tiny, hair-raising muscles beneath your skin - tighten, preparing you to spring into action.

Body systems not needed for the immediate emergency are suppressed. The stomach and intestines cease operations. Sexual arousal is quashed. Repair and growth of body tissues and bones halted.

All of this is exactly we need -- to hunt a mastodon or saber- toothed tiger, to fight an enemy, or to flee for our lives from a real and immediate danger.

In the early 70's I was threatened at midnight by a mugger with a knife in the East Village of New York City. I ran from him, many blocks to a subway station where there were lights and people. I ran faster than I knew was possible, thanks to the stress response which mobilized my body for flight.

Problems arise in modern life, however, where these physiological responses may be triggered fifty or more times a day in reaction to anxiety or stress-inducing situations, such as an exam or a fender-bender or an interaction with a difficult person. Normal life events, both positive and negative, may also induce a chronic stress response, lasting long after the stressful event has passed.

Chronic Stress Affects Health

How the physiological changes triggered by chronic activation of the stress response can compromise health.

The long-term activation of the stress response system can disrupt almost all your body?s processes, according to the Mayo Clinic Health Information (September 17, 2004). This can increase your risk of obesity, insomnia, digestive complaints, heart disease and depression.

These health risks may occur through the direct effects of chronic stress, such as by suppression of the immune system or by chronic constriction of major blood vessels. Risks to health may also occur through indirect effects of stress, as persons attempt to respond to chronic stress levels in less-than-healthy ways, such as by overeating, smoking, drinking too much, not exercising, or engaging in other risky behaviors.

Effects of Chronic Stress on Systems in the Body

The Mayo Clinic points out how various bodily systems may be affected through chronic activation of the stress response:

Digestive System

Stress hormones slow the release of stomach acid and the emptying of the stomach. The contents of the colon are more quickly passed. Continuously high levels of cortisol can increase appetite and cause weight gain.

Immune System

Chronic stress tends to dampen your immune system, making you more susceptible to colds and other infections. Continuously elevated cortisol levels switch off the immune and inflammatory responses that are the body?s responses to infections. In some cases stress can make your immune system overactive, resulting in an increased risk of autoimmune diseases.

Nervous System

If your fight or flight response never shuts off, stress hormones produce persistent feelings of anxiety, helplessness and impending doom. Over-sensitivity to stress has been linked with severe depression, sleep disturbances, loss of sex drive and loss of appetite.

Cardiovascular System

High levels of cortisol can raise your heart rate and increase your blood pressure and cholesterol levels. These are risk factors for both heart attacks and strokes.

Other Systems

Stress worsens many skin conditions - such as psoriasis, eczema, hives and acne - and can be a trigger for asthma attacks.

The chronic activation of the body?s stress-response system thus creates many health vulnerabilities. An important aspect of good health is learning how to deal with life stresses in constructive ways. This includes developing skills to turn the body?s stress- response system off when it is not needed, so that all bodily systems may rest and recover from the powerful effects of the stress hormones.

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