A sneeze consists of a deep inward breath that fills the lungs, a closing or partial closing of the throat, and a sudden increase in pressure in the lungs that forces air out. This increase in pressure is a result of muscles near the lungs that contract (tighten and shorten). Sneezing never happens during sleep because reflex signals do not pass to the part of the brain that causes muscles to move. When people sneeze, their eyes close. The speed of the air from sneezing is about 150 kilometers per hour or more. 