Yet researchers aren't sure if it's actually the act of laughing that makes people feel better. A good sense of humor, a positive attitude, and the support of friends and family might play a role, too.
"The definitive research into the potential health benefits of laughter just hasn't been done yet," says Robert R. Provine, professor of psychology and neuroscience at the University of Maryland, Baltimore County and author of Laughter: A Scientific Investigation.
But while we don't know for sure that laughter helps people feel better, it certainly isn't hurting.
Laughter Therapy: What Happens When We Laugh?
We change physiologically when we laugh. We stretch muscles throughout our face and body, our pulse and blood pressure go up, and we breathe faster, sending more oxygen to our tissues.
People who believe in the benefits of laughter say it can be like a mild workout -- and may offer some of the same advantages as a workout.
"The effects of laughter and exercise are very similar," says Wilson. "Combining laughter and movement, like waving your arms, is a great way to boost your heart rate."
One pioneer in laughter research, William Fry, claimed it took ten minutes on a rowing machine for his heart rate to reach the level it would after just one minute of hearty laughter.
And laughter appears to burn calories, too. Maciej Buchowski, a researcher from Vanderbilt University, conducted a small study in which he measured the amount of calories expended in laughing. It turned out that 10-15 minutes of laughter burned 50 calories.
While the results are intriguing, don't be too hasty in ditching that treadmill. One piece of chocolate has about 50 calories; at the rate of 50 calories per hour, losing one pound would require about 12 hours of concentrated laughter!
Laughter's Effects on the Body
In the last few decades, researchers have studied laughter's effects on the body and turned up some potentially interesting information on how it affects us:
Blood flow. Researchers at the University of Maryland studied the effects on blood vessels when people were shown either comedies or dramas. After the screening, the blood vessels of the group who watched the comedy behaved normally -- expanding and contracting easily. But the blood vessels in people who watched the drama tended to tense up, restricting blood flow.
Immune response. Increased stress is associated with decreased immune system response, says Provine. Some studies have shown that the ability to use humor may raise the level of infection-fighting antibodies in the body and boost the levels of immune cells, as well.
Blood sugar levels. One study of 19 people with diabetes looked at the effects of laughter on blood sugar levels. After eating, the group attended a tedious lecture. On the next day, the group ate the same meal and then watched a comedy. After the comedy, the group had lower blood sugar levels than they did after the lecture.
Relaxation and sleep. The focus on the benefits of laughter really began with Norman Cousin's memoir, Anatomy of an Illness. Cousins, who was diagnosed with ankylosing spondylitis, a painful spine condition, found that a diet of comedies, like Marx Brothers films and episodes of Candid Camera, helped him feel better. He said that ten minutes of laughter allowed him two hours of pain-free sleep.