Q. Can laughter really help me live a healthier life? Is there any scientific evidence that laughter is the best medicine?

A. A lady came to the hospital to visit a friend. She had not been in a hospital for several years and felt very ignorant about all the new technology. A technician followed her into the elevator wheeling a large, intimidating-looking machine with tubes, wires, and dials.

"I'd hate to be hooked up to that thing," she said.

"So would I," replied the technician. "It's a floor-cleaning machine." (From www.butlerwebs.com.)

If you laughed at this joke, you affected your brain chemistry. You increased your levels of feel-good neurotransmitters, such as dopamine, oxytocin and endorphin. You momentarily changed your physiology: Your breathing became faster, your pulse went up, and so did your blood pressure (although only temporarily; after laughing, blood pressure actually drops). You also burned extra calories.

Over time, laughter can have a profound effect on your body, mind, and spirit. Researchers have found that regular doses of hearty laughter can reduce stress, alleviate depression, decrease anxiety, increase blood flow, enhance immunity, reduce blood sugar, decrease pain sensitivity, reduce blood pressure, exercise your muscles and promote relaxation. It may also help prevent the appearance of aging by increasing blood flow to your face. Because of its effects on your cardiovascular and nervous system, laughter could help prevent many chronic diseases.

For those fighting serious illness, laughter may also be beneficial. Norman Cousins, author of "Anatomy of An Illness," credited laughter with helping him heal from a debilitating arthritic condition. He rented funny movies and famously laughed his way back to health.

Laughter is a universal language, regardless of race and culture. Everyone can laugh; science has shown that many animals laugh, too.

Can laughter be therapy? Dr. Madan Kataria, a medical doctor from India, thinks so. He founded Laughter Yoga, a laughter club, in 1995. While researching the health benefits of laughter, he became convinced that a prescription of 20 minutes of laughter a day would help keep the doctor away. He began with a small laughter yoga club in India; there are now more than 5,000 laughter clubs in 53 countries. Laughter Yoga participants do deep breathing and clapping exercises, chant, laugh intentionally using their lower abdominal muscles, and perform other laughter techniques. To learn more about Laughter Yoga and find classes in your area, visit www.laughteryoga.org.

A great way to laugh every day is to subscribe to a "joke of the day" Web site.

Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu, as well as author of "Natural Choices for Women's Health," published by Random House. You can reach her and read her past columns at www.DrSteelsmith.com. This column is for information only. Consult your health provider for medical advice.