Decrease stress, process food better and increase the power of your immune system, all by laughing? In one recent study researchers measured the effect of watching a funny movie on how heart blood vessels expand, or vasodilate. The researchers found that laughing increased blood flow as much as a 15- to 30-minute workout.There were 20 healthy men in the study, and all 20 watched both a stressful film (about war) and a funny film. After seeing the stressful film, 14 of the 20 participants had significantly reduced blood flow. However, after watching the funny film, 19 of the 20 volunteers …