Simply Science: The Solar Sneeze

5:32 PM, Aug 1, 2013   |    comments
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GOLDEN VALLEY, Minn. - In this week's Simply Science, our Laura Betker tackles a viewer question sent in via twitter. @PurpleReign23 asks, "Why do many people sneeze when they first see bright daylight in the morning?"

If you suffer from the "solar sneeze", you're not alone.

"People refer to it as the solar sneeze or the photic light reflex. It is basically when people are exposed to a bright light, or the sunshine and they start to sneeze repetitively, upwards of 40 times," says Dr. Douglas McMahon of Midwest Allergy and Asthma in Burnsville.

This harmless condition affects one in every 3 to 4 people... including our own Pat Evans, who laughs, "The big anxiety is if I'm going to be on air.  I've had it when I've been standing in the backyard, ready to do the weather and it's like... Oh please let this happen before the camera turns on, so there's anxiety with it but actually it's a relief when it happens."

Officially it is called the Autosomal Dominant Compelling Helio-Ophthalmic Outburst Syndrome, or for short: The ACHOO Syndrome. The cause is rooted in our facial nerves.

"Everyone has a big nerve called the trigeminal nerve," says the doctor.

Sensory information from the eye travels through that trigeminal nerve, but so do messages from the nose. In a solar sneezer, those messages get mixed up.

He continues, "So you have a stimulation of the opthalmic nerve, which is the eye nerve, then it can easily be confused as coming from the nose."

It often happens with the first bright light of the day, and then in many people doesn't happen for another 24 hours.


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