I'm Gwen Outen with the VOA Special English Health Report.
Have you heard the old saying that laughter is the best medicine? Then listen to this. Seriously, research has already shown that mental stress can restrict blood flow to the heart. But now a study has linked laughter to increased blood flow. Laughter appears to cause the tissue inside blood vessels to expand. As a result, laughing may be important to reduce the risk of heart disease.
So says Doctor Michael Miller of the University of Maryland Medical Center. He led a study of twenty men and women, all healthy. To get them to laugh, they watched part of the movie "Kingpin," a nineteen ninety-six comedy. To create the opposite emotions, they watched the opening battle in the nineteen ninety-eight war movie "Saving Private Ryan."
The researchers used ultrasound technology to measure changes in blood flow through an artery in the arm.
Blood flow increased in nineteen of the twenty people after they watched "Kingpin." The increase was an average of twenty-two percent. Doctor Miller says that is similar to the effects of aerobic exercise.
Blood flow decreased in fourteen of the twenty people after they watched "Saving Private Ryan." The decrease was an average of thirty-five percent.
Studies have shown that stress can reduce the body's ability to fight disease. When the body is under stress, it produces hormones such as adrenalin and cortisol. Cortisol is related to fear; adrenalin prepares the body to react. But too much of these hormones can be harmful.
Doctor Miller noted that the study could not explain how laughter is responsible for the effects observed. Do the effects come from the movement of muscles, or from a chemical release?
The researchers say laughter may cause the body to release pleasure chemicals, just as when a person exercises. Doctor Miller says these endorphins may block the effect of stress hormones and cause the blood vessels to expand. Laughter may also influence the release of nitric oxide, which too expands blood passages.
The results were presented at a meeting of the American College of Cardiology. Doctor Miller does not advise people to replace exercise with laughter. But, based on the results, he does suggest fifteen minutes of laughter each day.
This VOA Special English Health Report was written by Cynthia Kirk. Our reports are online at WWW.51VOA.COM. I'm Gwen Outen.