The phrase "bless you" or "God bless you" when someone sneezes originated from multiple historical and cultural beliefs. One common explanation is that people once believed sneezing caused the soul to be momentarily expelled from the body, and saying "bless you" was a way to protect the soul from evil spirits or the devil. Another origin dates back to the Middle Ages during the bubonic plague, where sneezing was seen as a sign of illness, and "God bless you" was said as a religious benediction hoping for the person's survival. Today, it is mostly used as a polite and customary response to a sneeze. In the United States, some people also say "Gesundheit," a German word wishing health, due to German immigrant influence.