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Laughing for your life
(China Daily)
Updated: 2005-03-12 09:29

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, said Michael Miller, who headed one research team at the University of Maryland.

On the other hand, depression - or the lack of laughter - is often linked to unhealthy habits such as smoking and drug addiction and increases the risk of death by 44 per cent, said Wein Jiang, who led a study of 1,000 heart patients for the University of North Carolina.

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 per cent during laughter, and decreased 35 per cent during mental stress.

"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," Miller said.

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.

On presenting the results of his research, Jiang said the "adverse association of depression and increased long-term mortality was independent on other factors, including age, marriage, cardiac function, the root cause of heart failure."

"Approximately half of all patients with heart failure will die within five years of diagnosis, and we believe that our study appears to identify a group of these patients who are at a higher risk (44 per cent) of dying," she added.

Jiang was also unable to explain the results of her research theorizing instead that "depressed patients tend to make unhealthy lifestyle choices in such areas as diet and smoking."

Both studies, however, appear to show that emotional states can lead to real physiological changes.

In February, researchers from the United States released details of a study which indicated emotional shocks such as the end of a relationship or a surprise party can kill otherwise healthy people. They called it a "broken heart syndrome."

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