What's the magic benefits for the laugh?

Many believe: Laughter is good medicine improving blood flow, blood sugar, immune response, and sleep. Evidence is variable. Webmd notes 'researchers aren't sure if it's actually the act of laughing that makes people feel better. A good sense of humor, a positive attitude, and the support of friends and family might play a role, too...But while we don't know for sure that laughter helps...It isn't hurting.'.