Sometimes, laughter really is the best medicine. According to the Mayo Clinic, laughter may help relieve stress, reduce pain, and improve mood.
In one small 2003 study, researchers put 16 volunteers in an MRI brain scanner and showed them cartoons rated as funny or not-funny by volunteers. When a different set of people saw the funny cartoons, scientists saw a boost in blood flow to several parts of the brain's "reward" system — specifically, the ventral tegmental area (VTA), nucleus accumbens, and amygdala. And the funnier the cartoons, the bigger the brain response — and presumably, the more tickled people felt.