Laughing appears to be almost as beneficial as a workout in boosting the health of blood vessels, a new study suggests.
鈥淭hirty minutes of exercise three times a week and 15 minutes of hearty laughter each day should be part of a healthy lifestyle,鈥� says Michael Miller of the University of Maryland Medical Center in Baltimore, US, whose team has shown that laughter relaxes arteries and boosts blood flow.
He showed clips from the comedy movie King Pin to 20 volunteers. Before and afterwards, he made ultrasound measurements of blood flow and dilation in the brachial artery in the arm. The scans showed that in all but one of the volunteers, the volunteers鈥� arteries relaxed and blood flowed more freely than usual for 30 to 45 minutes after the film.
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The opposite happened when the same people watched harrowing scenes from the war movie Saving Private Ryan. In 14 of the 20 volunteers, the artery wall constricted, reducing blood flow. Overall, blood flow decreased by 35% after the stressful clips and increased by 22% during laughter.
Laughter linings
The results suggest that laughter could help keep the lining of the arteries 鈥� the endothelium 鈥� healthy and thus reduce the risk of cardiovascular disease. 鈥淎t the very least, laughter offsets the impact of mental stress, which is harmful to the endothelium,鈥� Miller says.
鈥淚t鈥檚 logical that positive emotions might have the opposite effect,鈥� says Andrew Steptoe of University College London, UK, whose studies in 2000 showed that acute mental stress impairs endothelial function. 鈥淭here is increasing scientific interest in the possibility that positive emotional states are beneficial to health,鈥� he says.
Miller, who presented his results to the American College of Cardiology meeting in Orlando, Florida, on Monday, now hopes to find out why laughter is beneficial. 鈥淲e don鈥檛 know if there鈥檚 a direct effect by laughing, or an indirect effect by reducing stress.鈥�
