Much interest in the medical use of relaxation has been for patients suffering from cardiovascular problems. A report in the British Medical Journal, for example, reported that patients who had been trained in deep relaxation significantly lowered their blood pressure, and had maintained that reduction four years later. In research at Harvard Medical School, associates of Benson found that regular sessions of a simple meditation technique decreased the body's response to norepinephrine, a hormone released in reaction to stress. Although the endocrine system continued to emit the hormones, they did not seem to have their usual effects. But regular relaxation training resulted in less blood pressure increase to norepinephrine than is usually seen.
Relaxation seems to mimic the action of the beta-blocking drugs used to control blood pressure.
Research by Dean Ornish, director of the Preventive Medicine Research Institute in San Francisco, has shown that relaxation training improves blood flow to the heart. Silent ischemia, which chokes off that blood flow, can damage the heart without causing noticeable pain. He also found that relaxation lowered cholesterol levels and lessened the severity of angina attacks. In 1984, A National Institutes of Health report recommended the use of relaxation, along with salt restriction and weight loss, as the first therapy for mild hypertension, before resorting to drug treatments. Nevertheless, many cardiologists have been slow to use the relaxation techniques.