Every time some people go out into the sun, they sneeze: why does it happen? (Image: RESO / Rex Features)

Are you a photic sneezer? Take the questionnaire and find out

I WAS rounding the corner to the bus stop when it hit me – a bright shaft of sunlight smack between the eyes. My reaction was immediate: an unpleasant prickling in my nose, a quickening of my breath, an uncontrollable watering of my eyes. Then, almost as quickly as the sensation came, relief, blessed relief. Aaaaa-tisshoo! A sneeze.

It wasn’t the first time. In fact, the same thing happens every time I go into the sun. For a long time, I thought it was a quirk all of my own. Then a friend mentioned she was similarly afflicted. Next my mother came out of the closet. With a bit of digging around I came to a startling realisation: not only am I not alone, but the “photic sneeze reflex” is actually common. Quite how common, no one knows exactly – but anything between 1 in 10 and 1 in 3 of us might be affected.

The more I looked, the more mysterious things became. Sunlight is the most widespread, but by no means the only, odd stimulus that sets off sneezing. Thinking about sex, eyebrow tweezing, eating chocolate or a mint, or drinking a glass of wine – all these activities can leave us groping around for handkerchiefs. Members of one Kuwaiti family were even reported to sneeze whenever they had a full stomach – a phenomenon dubbed “snatiation”. Then there was the case of the medical student who sneezed with almost …