The Stress Response
The stress response is a set of changes in the body that result when the person experiences what they perceive to be a challenging or threatening situation. This matter of perceived threat is important because the effects of the stress response on the body are the same whether the threat is real or just imagined in the mind.

The magnitude of these changes is influenced by how serious the person thinks the situation is and what they think about their ability to handle the threat effectively (their appraisal of their ability to respond). Of course, the more confident the person is in their ability to handle a challenge easily, the less stress is involved. The more the person appraises the challenge as a threat—even at the subconscious level—the more intense will be the stress response.

Commonly called the fight-or-flight reaction, the stress response has the beneficial effect of preparing the body to function at a higher level of efficiency, which of course enhances the likelihood of survival. The physiological changes include:

• Increased blood pressure
• Increased respiratory rate
• Increased heart rate
• Increased oxygen consumption (burning of fuel)
• Increased blood flow to skeletal muscles
• Increased perspiration
• Increased muscle tone

While all these changes clearly contribute to one's ability to fight or flee in an emergency, they also have a downside. If the person is experiencing the stress response regularly and for extended periods of time, these physiological changes have the effect of weakening the body's resistance to illness and lowering the effectiveness of its mechanisms of self-repair.

The Relaxation Response
Another key principle is the relaxation response, which was discovered and named by Herbert Benson, M.D., and his colleagues in 1974.^7,8 They were studying a pattern of physiological changes that occurs in people practicing transcendental meditation (TM).

This pattern of changes has been found to represent a very beneficial state, one that is virtually a mirror image of the stress response. The relaxation response includes the following changes:

• Reduced blood pressure
• Reduced respiratory rate
• Reduced heart rate
• Reduced oxygen consumption (burning of fuel)
• Reduced blood flow to skeletal muscles
• Reduced perspiration
• Reduced muscle tension

The relaxation response is an antidote to the effects of the stress response and it has also been found to enhance the effectiveness of the body's defenses and self-repair mechanisms. Regular practice of techniques that elicit this response also brings improved emotional well-being and better handling of stressful life events.

The relaxation response is a physiological state, not a technique as such. As we shall see later, there are many techniques that can be used to produce it and, indeed, learning to do this is at the heart of mind/body medicine.

Coping, Emotions, and Health
Researchers have identified how the ways we cope with emotions and stressful situations—our coping styles—can influence our physical health. Most firmly established are the links between coronary heart disease and the Type A behavior pattern. Type A is a way of coping characterized by constant hurriedness, intense competitiveness, and free-floating hostility.