Patients, doctors and health-care professionals are all finding that laughter may indeed be the best medicine.

Laughing is found to lower blood pressure, reduce stress hormones, increase muscle flexion, and boost immune function by raising levels of infection-fighting T-cells, disease-fighting proteins called Gamma-interferon and B-cells, which produce disease-destroying antibodies. Laughter also triggers the release of endorphins, the body's natural painkillers, and produces a general sense of well-being.

Laughter is infectious. Hospitals around the country are incorporating formal and informal laughter therapy programs into their therapeutic regimens. In countries such as India, laughing clubs -- in which participants gather in the early morning for the sole purpose of laughing -- are becoming as popular as Rotary Clubs in the United States.

Humor is a universal language. It's a contagious emotion and a natural diversion. It brings other people in and breaks down barriers. Best of all it is free and has no known side reactions.

Finding humor in a situation and laughing freely with others can be a powerful antidote to stress. It is also a very good coping mechanism when you are suffering from deadly diseases such as cancer. Many people find that maintaining a sense of humor at such occasions are useful for good quality of life. Our sense of humor gives us the ability to find delight, experience joy, and to release tension. This can be an effective self-care tool. Scientific evidence on the effectiveness of humor as a therapy is now overwhelming.

For many years medical professionals have recognized that those patients who maintained a positive mental attitude and shared laughter responded better to treatment. Physiological responses to laughter include increased respiration, circulation, hormonal and digestive enzyme secretion, and a leveling of the blood pressure. Many report a general sense of euphoria after vigorous laughter. But until the New England Journal of Medicine in 1979 published the Norman Cousins case study, few considered the therapeutic uses of humor.

The first documented case of humor positively affecting disease was in 1964 when Norman Cousins, published "Anatomy of an Illness". Medical professionals were for the first shown that humor biologically reversed Cousins' ankylosing spondylitis, a painful disease causing the disintegration of the spinal connective tissue. Given a one in five hundred chance of recovery, Cousins decided to infuse himself with humor treatments. With Cousins' self-designed humor treatments, he found that 15 minutes of hardy laughter could produce two hours of pain free sleep. Blood samples also showed that his inflammation level was lowered after the humor treatments. Eventually Cousins was able to completely reverse the illness. Cousins later documented his story in a book he called "Anatomy Of an Illness."

Today, interest in humor's effects has grown so much that the field has a name -- psychoneuroimmunology, the study of how psychological factors, the brain and the immune system interact to influence health.