When people feel stress, their bodies undergo a programmed response controlled by brain regions such as the amygdala and the hypothalamus. This triggers a series of physiological and hormonal responses by the adrenal glands.

When we are afraid, the hormone epinephrine flows through the bloodstream, which increases heart and breathing rates, tightens muscles, and causes sweating. This “fight-or-flight” response helps people to react rapidly to life-threatening situations. In a dangerous situation, this reaction is appropriate.

But when the response becomes chronic, stress hormones like cortisol contribute to various health problems including heart disease, hypertension, diabetes, anxiety, and depression. Biofeedback has been used extensively to facilitate relaxation training that helps people improve their ability to practice yoga, meditation, and deep breathing exercises.

It also has been used to improve the effectiveness of guided imagery and psychotherapy that stimulates positive emotions.

In addition to facilitating relaxation training, biofeedback can improve a person’s ability to recover from stressful situations and negative emotional experiences.

For this form of treatment, a person undergoes biofeedback training right after a simulated stressful experience. The training raises the person’s level of awareness of stress responses so he or she can learn how to better manage them.