Here are five things you didn't know about laughter:
1. Is laughter the best medicine? Laughter may reduce your risk of cardiovascular disease. Researchers at the University of Maryland Medical Center in Baltimore have found that laughter is linked to healthy function of blood vessels by causing the inner lining to expand, increasing blood flow.
2. Laugh it off: Laughing just 15 minutes a day can help you lose weight. No joke. Scientists at Vanderbilt University in Nashville, Tenn., have discovered that a daily dose of chuckling can burn up to five pounds of fat over a year. Ten to 15 minutes of laughter could increase energy expenditure by 10 to 40 calories per day.
3. The world laughs with you: There's now scientific proof that laughter is contagious. Researchers at University College London found that hearing laughter and other positive sounds triggers a response in the area of the brain that's activated when we smile.
4. Belly laugh: A good laugh stimulates your organs, soothes tension and tummy aches, improves your immune system, relieves pain and increases personal satisfaction, according to a Mayo Clinic advisory on stress.
5. Send in the clowns: Laughter and its effects on the human body is a hot field of study called gelotology. Humor therapy, clown therapy and laughter meditation are being used by doctors, psychiatrists and other mental health professionals.