May 29 (HealthDay News) -- New research lends weight to the old adage that laughter can be powerful medicine, particularly when it comes to your heart.
Two studies presented at the American College of Sports Medicine's annual meeting in Seattle found that laughter not only can reduce stress, which can damage the heart, it can lead to improved blood flow, which can help ward off high blood pressure.
The first study included a small group of healthy adults who were asked to watch either a comedy or documentary film. They were then checked for activity of the carotid arteries -- the main arteries in the neck that bring blood to the brain and face -- during the films.
People who watched the comedy displayed improved "arterial compliance" -- the amount of blood that moves through the arteries at a given time. Decreased arterial compliance is often linked with high blood pressure and heart disease, according to an American College of Sports Medicine news release.
"Arterial compliance was improved for a full 24 hours after subjects watched a funny movie," said lead researcher Jun Sugawara. "Laughing is likely not the complete solution to a healthy heart, but it appears to contribute to positive effects."
The second study focused on vascular function and the dilation of blood vessels. When a second group of adults watched either a comedy or a serious documentary, there was more dilation of blood vessels during the comedy. Constricted blood vessels can be a cause of high blood pressure, the news release said.
"Not only did comedies improve vascular dilation, but watching a documentary about a depressing subject was actually harmful to the blood vessels," said Takashi Tarumi, lead researcher on the second study. "These documentaries constricted blood vessels by about 18 percent."
In both studies, the beneficial effects of laughter lasted for 24 hours, the researchers said.
The college's annual meeting concludes May 30.
SOURCE: May 29, 2009, news release, American College of Sports Medicine