Myrl Jeffcoat myrlj@jps.net

8 mars, 2005 09:22

Laughter the best medicine

08/03/2005 21:51 - (SA)

Jean-Louis Santini

Orlando - Laughter is good for the heart because it prolongs life while depression increases the risk of an early death, according to two new studies.  A good bout of laughter every day provides similar cardiovascular benefits as exercise, because it stimulates the blood-flow, says Michael Miller, who headed one research team at the University of Maryland.  Wein Jiang, who led a study of 1 000 heart patients for the University of North Carolina, said that, on the other hand, depression - or the lack of laughter - was often linked to unhealthy habits such as smoking and drug addiction and increased the risk of death by 44%.

Miller said laughter produced a “magnitude of change ... in the endothelium ... similar to the benefit we might see with aerobic activity, but without the aches, pains and muscle tension associated with exercise”.  While laughter should not replace exercise, he said, “we do recommend that you try to laugh on a regular basis”.  “Thirty minutes of exercise three times a week, and 15 minutes of laughter on a daily basis is probably good for the vascular system.”  Miller told the American College of Cardiology annual conference that he showed excerpts of funny and stressful films to 20 non-smoking, healthy volunteers, equally divided between men and women, whose average age was 33.

Researchers measured changes in blood-vessel reactivity as the volunteers watched the movies, and noted striking contrasts.  Artery flow in the arms was reduced in 14 of the 20 volunteers following the movie clips that caused mental stress.  In contrast, beneficial blood vessel relaxation increased in 19 of the 20 volunteers after they watched the movie segments that generated laughter.  Overall, average blood flow increased 22% during laughter, and decreased 35% during mental stress.  Couldn’t explain the physiology  Miller said: “The endothelium is the first line in the development of atherosclerosis or hardening of the arteries, so, given the results of our study, it is conceivable that laughing may be important to maintain a healthy endothelium, and reduce the risk of cardiovascular disease.”

However, the researcher was unable to explain the physiology of laughter’s benefits.  “Does it come from the movement of the diaphragm muscles as you chuckle or guffaw, or does it come from a chemical release triggered by laughter, such as endorphins?  “Perhaps mental stress leads to a breakdown in nitric oxide or inhibits a stimulus to produce nitric oxide that  results in vasoconstriction,” he added.

http://www.news24.com/News24/Technology/News/0,,2-13-1443_1673302,00.html#