When you step outside from a dark building into the full glare of the sun, do you suddenly have the urge to sneeze? If so, you're not alone — as many as 1 in 3 people display this reaction.
This reflex, called the photic sneeze reflex, has been observed since at least the fourth century B.C., when the ancient Greek philosopher and scientist Aristotle posed the question, "Why is one more apt to sneeze after looking at the sun?"
