A study by researchers at the University of Maryland found that laughing while watching a comedic film causes your blood vessels to dilate by 22 percent. That's because when you laugh, the tissues forming the lining of your blood vessels expand and make room for an increase in blood flow. Translation: When you laugh at the movies, you're actually lowering yourblood pressure to the same extent that you'd lower it when you do physical exercise, said Dr. Michael Miller, director of the University of Maryland's Center for Preventive Cardiology.
To get the biggest heart-healthy benefit from watching comedies, you should be watching movies that make you do a real belly laugh for at least 15 minutes, Miller said.
