What Cousins discovered on his own, researchers have recently been trying to prove through scientific study: that laughter can relieve pain, reduce depression, promote relaxation, boost the immune system, improve blood flow and breathing, lower blood pressure and glucose levels, and even slow the growth of cancer cells. “Studies indicate that participating in laughter therapy is beneficial in terms of disease control,” says William Fry, M.D., professor emeritus at the Stanford University School of Medicine.
Just how powerful a medicine laughter may be was demonstrated by Michael Miller, M.D., director of preventive cardiology at the University of Maryland Medical Center. In 2006, in the journal Heart, Miller reported on a group of 20 healthy volunteers, none suffering from heart disease or high blood pressure, randomly assigned to watch a 15- to 30-minute segment of either a comedy film, to induce laughter, or an action-packed drama, to cause mental stress.
Miller measured the flow of blood in his subjects’ brachial arteries in the upper arm before and after the movies. Nineteen of the 20 people who watched the comedy experienced increased blood flow by a mean of 15 percent, suggesting that laughter relaxes the arteries and may ease strain on the heart. On the other hand, 14 of the 20 volunteers who watched the drama found that blood flow in their arteries was reduced by a mean of 47 percent, an amount Miller compares to a fit of anger, which may raise blood pressure, constrict arteries and stress the heart.
“We think this is the real deal,” says Miller. “There’s no question in my mind that there is some physiological benefit from laughter. Now, we need to translate what those changes in our blood vessels mean clinically.”
California researcher Lee Berk, an associate professor at Loma Linda University School of Public Health, is documenting laughter’s ability to boost immune cell activity and improve mood. “Just the anticipation of laughter can change your biology, lower stress hormones and increase endorphins that affect mood states and vigor,” says Berk.
In a 2006 study, Berk and his colleagues found that body chemicals called beta-endorphins, nature’s pain relievers and antidepressants, increased by 27 percent when volunteers simply anticipated watching a humorous video. Human growth hormone, which boost immunity to disease, also rose in the volunteers—by 87 percent. No increase in these hormones occurred in the control group, which wasn’t told they would see the video.
This year, the same researchers looked at the impact of anticipating laughter on three major stress hormones. High levels of stress hormones can have a detrimental impact on the immune and cardiovascular systems. All three stress hormones were reduced when subjects anticipated seeing the funny video—and one, epinephrine, dropped by 70 percent.
Although there’s no scientific explanation, it’s widely known that one of laughter’s most therapeutic characteristics is that it is extremely contagious. Recently, Millie Mund decided to spread a little cheer by introducing laughter yoga to her son, daughter-in-law and adult grandchildren. “They thought I was crazy,” she says, “but before I knew it, they were all doing ‘ho ho, ha ha ha’ and laughing!”
Sally Abrahms of Brookline, Mass., writes about health, workplace and aging issues.