The laughing Uncle Albert in “Mary Poppins” may have been onto something. Researchers are now finding scientific evidence that laughing is not only good for us psychologically, but may play a major role in blood pressure and cardiovascular health.

The University of Maryland Medical Center has been at the forefront of laughter research. Their first significant findings were presented in 2000 to the American Heart Association’s 73rd Scientific Sessions. The study surveyed a group of 300, half of whom had suffered a heart attack or had undergone coronary artery bypass surgery and the other half who were of the same age but did not have heart disease. The two questionnaires featured either multiple choice or true/false questions to determine the participants’ likeliness to laugh in situations and their levels of anger and hostility. You can take a sample survey here. Their findings revealed that those with a history of heart disease were 40% less likely to laugh than those without the disease.

The second major study by the University of Maryland presented in 2005 focused on monitoring changes in the blood vessels, specifically the endothelium (inner lining), as participants experienced different emotions. When the volunteers were shown intense and stressful clips of movies their blood vessels reduced blood flow (called vasoconstriction) by an average of 35%. However, when participants viewed clips of a funny film, their endothelium dilated and expanded to increase blood flow an average of 22%. Further research in 2008 found that during laughing the participants’ mean flow-mediated dilation was 19%. It is believed that an unhealthy endothelium is the first step in developing hardened arteries (atherosclerosis). The study showed that laughing may help keep the endothelium healthy which should theoretically improve one’s defense against heart disease and high blood pressure.

“The magnitude of change we saw in the endothelium is similar to the benefit we might see with aerobic activity, but without the aches, pains and muscle tension associated with exercise,” said Dr. Miller, who led the research and is director of preventive cardiology at the University of Maryland Medical Center, “We don’t recommend that you laugh and not exercise, but 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.”

More information on the study in 2000 can be found here, the 2005 study and Miller quote here and the 2008 study here.