Laugh your way to better blood vessel function by watching a funny flick.

Laughter relaxes blood vessels and increases blood flow -- the exact opposite of what your blood vessels do when you are stressed. In a small study of healthy men and women with normal blood pressure, watching a funny movie increased blood flow by about 22 percent. If funny movies aren't your style, spend time with the people who tickle your funny bone.

Blood vessels are lined with a layer of cells called endothelium; they regulate blood flow by helping blood vessels expand and contract. In a small study, healthy men and women watched either a funny movie or an intense, violent one while researchers measured blood flow through an artery in their upper arm. Watching the funny movie caused blood vessels to dilate, increasing blood flow by about 22 percent. The action movie caused mental stress and blood vessel constriction, decreasing blood flow by about 35 percent. Having relaxed blood vessels decreases strain on the heart. Researchers aren't exactly sure how mood states affect blood vessels. Different mood states may alter levels of hormones, such as cortisol, that affect blood vessel function or nitric oxide function. Nitric oxide is a chemical messenger that promotes blood vessel relaxation. Proper diet and regular exercise are the mainstays of improving blood vessel health, but laughing often is a great adjunct.