The idea that a sneeze stops your heart is up there with the ancient belief that a big ah-choo blows your soul right out of your nose . Both are myths with murky origins, and neither makes much sense.
Sneezing or, if you like to impress your friend with big words, sternutation is a reflex centered in a section of the brainstem called the medulla. When something tickles the upper lining inside the nose, nerves carry the signal to the medulla, which then triggers the eyes to close, the chest to contract, and the lungs to expel a burst of air at speeds approaching 100 mph.
But one thing the brain doesn't do is signal the heart to stop. It keeps beating no matter how hard you sneeze . So sternutate away, but please, remember to cover your mouth first. That helps prevent the spread of disease, and besides, we wouldn't want your soul to get out.