Answer: No

The heart does not in fact stop when you sneeze, but a sneeze does have an effect on the heart that gives the impression that it might be stopping.

A sneeze has been described by scientists as an involuntary blast of air from the nose to remove material ailments from the nostrils. A sneeze begins with a tickling sensation in the nose, relaying a message to your brain that something is present irritating the lining of the nose. Air pressure builds up in the lungs, your eyes close, your tongue lifts to the roof of your mouth, and you force high pressure air out of your nose (ie. sneeze). The increased pressure inside the chest affects the heart beat which is where the myth that your heart stops when you sneeze probably arose, this however is not the case. The increased pressure in the chest reduces blood flow back to the heart which the heart compensates for by changing its rhythm; so while your heart may skip a beat, the electrical activity of the heart doesn’t stop when you sneeze.