Can sunlight make you sneeze?

ACHOO! Yes! Sunshine can make some people sneeze. In fact, bright light of any kind can trigger a sneeze reflex in those affected. This is called photic sneeze reflex. It's also known as ACHOO syndrome. ACHOO stands for Autosomal Dominant Compelling Helio-opthalmic Outburst. Try saying that three times fast!

Reported to affect 18 to 35 per cent of the population, the syndrome is an inherited trait. That means it's passed from a parent to a child through a parent's DNA. Although the term ACHOO syndrome wasn't coined until the 1970s, people have experienced "sun sneezing" long before that. Ancient Greeks thought the sun was warming the nose and causing irritation. 

There have been studies where affected people closed their eyes while in the sun. Guess what happened? They didn't sneeze! Hmm… does this mean it is exposure to light and not warmth that causes this effect? The pupils of our eyes contract when exposed to bright light. Is the sneeze reflex related?

Scientists aren't exactly sure how, but there are different theories. It might be because of the nerves that connect our eyes and nose. Signals on those nerve pathways could get mixed up because they're so close together. Or it could be because of our parasympathetic nervous system. When one part of the system receives a stimulus, other parts tend to get activated as well.

Whatever the reason, always remember to cover your sneeze. Gesundheit!