The researchers relied on laughter-provoking movies to gauge the effect of emotions on cardiovascular health.
They said laughter appears to cause the tissue that forms the inner lining of blood vessels, the endothelium, to dilate or expand in order to increase blood flow.
When the same group of study volunteers was shown a movie that produced mental stress, their blood vessel lining developed a potentially unhealthy response called vasoconstriction, reducing blood flow.
The results of the study were presented Monday at the Scientific Session of the American College of Cardiology in Orlando, Florida.
"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," said principal investigator Michael Miller.