A good belly laugh has a rallying effect that no chuckle can match. A British study in 2011 showed that, like sex and exercise, the physical effort of uncontrollable laughter makes our brains release chemicals called endorphins, which relax us and relieve pain. It is “the emptying of the lungs that causes” the feel-good effect, not just the thought of something funny, evolutionary psychologist Robin Dunbar tells BBCNews.com.
He and his colleagues at Oxford University asked volunteers to watch either a comedy or a documentary, and then applied painful levels of cold or pressure to their arms. The volunteers who had laughed hard during their videos could withstand 10 percent more pain than those who’d only giggled or who hadn’t been amused at all.