Mental stress can take a toll on your health. So it stands to reason that having a good laugh may boost your health. In a study presented at a recent meeting of the American College of Cardiology, researchers tested the blood vessel health of 20 participants by using an arm cuff to constrict the vessels and then release. (Healthy blood vessels dilate more after release and are less likely to form blood clots.) Participants then watched scenes from the comedy “King Pin” and the tragic war movie “Saving Private Ryan” and underwent the blood vessel test after each movie. After watching comedy scenes, viewers’ blood vessels dilated more, whereas the war scenes led to more vessel constriction.