Why Is One Person's Laugh a Potential Epidemic?

Feeling down and out? A good laugh may be your best medicine. If you think there’s nothing out there that's funny enough to crack you up, check out the video here. We can almost guarantee that you’ll laugh (or at least crack a smile). You can’t fight it—laughter is contagious. Literally.

Studies by researchers at University College London have shown that when you hear someone laughing, your brain primes the muscles in your face to smile or laugh, too. Scientists see this mirroring of positive emotions as an important social factor, helping to build strong bonds between individuals in a group.

That explains why, when you walk up to people who are laughing about something you know nothing about, you start smiling, too. It also explains why hanging out with people who laugh a lot is so enjoyable. Laughing is one of the best stress reducers out there. And it’s free.