Laughter is good for the heart

2 October 2011

Having a good laugh has a positive effect on blood flow, while stress constricts blood vessels and restricts blood flow.

A study by the the University of Maryland School of Medicine in Baltimore, Maryland found that watching a funny movie or sitcom that produces laughter has a positive effect on vascular function and watching a stressful movie has a negative effect. The study was presented at the European Society of Cardiology Congress 2011 in Paris at the end of August.

"The idea to study positive emotions, such as laughter came about after studies had shown that mental stress caused blood vessels to constrict", said Dr Michael Miller, Professor of Medicine and lead investigator.

Volunteers watched segments of a funny movie on one day and on another day watched part of a stressful movie (Saving Private Ryan). Each volunteer served as his or her own control.

When study volunteers watched the stressful movie, their blood vessel lining developed a potentially unhealthy response called vasoconstriction, reducing blood flow. This finding confirms previous studies, which suggested there was a link between mental stress and the narrowing of blood vessels. However, after watching the funny movie, the blood vessel lining expanded.

Overall, more than 300 measurements were made on 20 non-smoking healthy men and women using ultrasound to measure blood vessel diameter. The results showed that blood flow was enhanced by 22% in those watching the funny film, but decreased by 35% in those watching the stressful film — giving a 30-50% difference in blood vessel diameter between the laughter (blood vessel expansion) and mental stress (blood vessel constriction) phases. “The magnitude of change we saw in the endothelium after laughing was consistent and similar to the benefit we might see with aerobic exercise or statin use” says Dr Miller.

“We’re not talking about a simple chuckle," he said, "but real mirthful laughter," which, he added, should last for at least 15 seconds. Laughter, he explained, might exert its beneficial effect through the release of endorphins by the brain, which activate receptors on the endothelium which in turn lead to the release of nitric oxide. “Nitric oxide dilates blood vessels, reduces inflammation, cholesterol deposition and clotting,” said Miller.

The endothelium has a powerful effect on blood vessel tone and regulates blood flow, adjusts coagulation and blood thickening, and produces chemicals in response to injury and inflammation. It also plays an important role in the development of cardiovascular disease.

“The endothelium is the first line in the development of atherosclerosis or hardening of the arteries, so it is very possible that laughing on a regular basis may be useful to incorporate as part of an overall healthy lifestyle to prevent heart disease. In other words, eat your veggies, exercise and get a good belly laugh every day" says Dr. Miller.

Although the results of the brachial artery blood flow measurements appear to make a connection between laughter and vascular health, more studies are needed. "What we really need is a randomized clinical trial to determine whether positive emotions reduce cardiovascular events above and beyond today's standard of care therapies", concluded Dr Miller.


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