Hi preshous333! Great question…sneezing is a convulsive expulsion of air from the lungs through the nose and mouth. It can be caused by foreign particles that irritate the inside of our nose! A sneeze expels air really quickly from the mouth and nose in an explosive, involuntary action. Some of the reasons why we might sneeze include sudden exposure to bright light, sudden decreases in temperature, breezes of cold air, or a viral infection. I think the main reason we sneeze though is because something has got inside our nose and irritated it! I don’t think anyone really knows why we can’t keep our eyes open when we sneeze! Some scientists think that we close our eyes to protect them. We may be protecting our eyes from microorganisms and particles from our sneezes. But it could also be simply because a sneeze is a kind of bodywide reflex in which a lot of muscles contract, not just in the nose and throat but also those in lots of parts of our body…so our eyes may close because the muscles that keep them open contract! Interesting question that scientists are still trying to work the answer out to!