You probably know it’s polite to say ‘bless you’ when someone sneezes in the UK, but did you know the custom might have originated in the sixth century? The theory is that sneezing was seen as the first symptom of the plague, so people would say a blessing to ward off the disease.
Another theory is that people thought sneezing stopped your heart, just for a moment, and saying ‘bless you’ would make sure your heart keeps beating.