Next time you hear a funny joke you'd better not laugh too hard. According to a paper published by the British Medical Journal, laughter isn't always the best medicine. Sometimes it can even be harmful. Professor Robin Ferner from the University of Birmingham, one of the authors of the study, found that bad things could happen to people who laughed too much. He says: "We found people with heartbeat problems which had stopped their heart, we found people who had fainted, and we found people who'd dislocated their jaws or burst their lungs." It seems that laughing can be no laughing matter. But it's not all _ . Professor Ferner says there are benefits to laughing when you want to lose weight, for example. Yes, that's right: laugh and be slimmer! Professor Ferner explains that: "You use energy when you laugh, you move your diaphragm  , you expand your lungs, and both those things can be helpful." According to the research, laughing for a quarter of an hour can burn up to 40 calories, and if you laughed all day you'd use up about 2,000 calories, which is what most people consume in a day. But don't do that or you might end up with a painful jaw. Ouch! Or you might find people looking at you in a funny way. But I don't want to finish this article leaving you feeling desperate. Laughter comes naturally for most of us. Babies begin to laugh at around 3-6 months. So give in to your sense of humour and keep smiling. Life is short anyway. Laughing too much may cause the following harmful results EXCEPT  _  .
heart stop diaphragm movement lung burst jaw dislocation