a light sneeze

September 28, 2005 5:58 AM

Why does looking at a bright light assist in sneezing?

I thought I was the only person doing this, but saw a co-worker do it-
Staring at a bright light to facilitate an oncoming sneeze.

What is it about the light that pushes that sneeze from a tickle to a roaring blast of nasal spray?

posted by phredhead to Society & Culture (18 answers total)

I do it and it's called Photic Sneezing. A wee look here will tell you the rest...
posted by brautigan at 6:05 AM on September 28, 2005

The same thing happens to me. I also sneeze sometimes when I step outside into the bright sun. I've always wondered why myself, so glad you asked.
posted by jdl at 6:12 AM on September 28, 2005

"The photic sneeze reflex is considered a risk factor to combat pilots: people suffering from photic sneeze reflex may not fly combat aircraft."

Damn, there goes that dream.
posted by furiousxgeorge at 6:20 AM on September 28, 2005

Ah yes, the reflex is described as "people going from dark to sunlight, then sneeze"

Is this the same reflex? This happens to me too, but I don't sneeze just due to a lighting change. It's more of an assistance to look into a bright light to help me finish an oncoming sneeze
posted by stevejensen at 6:22 AM on September 28, 2005

Another name for the photic sneeze reflex is ACHOO syndrome:
Autosomal-dominant Compelling Helio-opthalmic Outburst Syndrome.

I kid you not - you can Google it under this name.
posted by edd at 6:29 AM on September 28, 2005

I find this question amusing becuase while I don't have this reflex, my dog does. Seriously. I always wondered why when I took her into the hallway of the apartment building in the morning - where there is bright lights - she sneezed several times. Amazing.
posted by dpx.mfx at 6:35 AM on September 28, 2005

I often entertained this wild speculation that it was an evolutionary adaptation from when our ancestors were cave- or hut-dwellers or something to discourage the transmission of disease. Presumably when you go from dark to light it means you've left your shelter and are outside, so sneezing now is "safer" than doing so inside.

Certainly that hypothesis has tons of flaws and I have no evidence whatsoever, but it kinda reminded me of the urge to pee when around running water - an unconscious urge which would seem to promote good hygene in someone who didn't know better.
posted by mragreeable at 6:37 AM on September 28, 2005

I do it and my son does it (who's 2) - I've never bothered to read any literature on it and I've never really discussed it meaningfully - but watching my son since birth has allowed me to reassess or even simply acknowledge a bunch of things I've always taken for granted.

My incredibly simplistic hypothesis is that it's a reflex to avert babies looking directly into the sun and thus doing damage to their retinas.

Now I'll go and read the literature.
posted by strawberryviagra at 6:58 AM on September 28, 2005

I have this, too, and for the first 20 years of my life I thought I was the only one, but then I met a coworker who also had it and that illusion shattered.

mragreeable, my friend told me that story once, too, but then I asked him why, if that was an evolutionary adaptation, so few people have this today? I think that's just a story concocted by Bright Light Sneezers to make us feel more useful.
posted by ducksauce at 8:00 AM on September 28, 2005

Hey, I've got this too!

And I heard the story that it was an adaptation to induce sneezing after we left those musty old caves. Clear out the sinuses after being inside.
posted by cptnrandy at 8:32 AM on September 28, 2005

I call it my allergy to the sun.
posted by mischief at 9:17 AM on September 28, 2005

Same here Mischief.

In grade-school we used to have to line up in the dark hall and then go outside to our bus. I'd always sneeze and the other kids said I was a vampire because I was allergic to the sun.

Now friends always stare at me in anticipation when we leave a movie theater during the day then snicker when I sneeze, like always.
posted by Animus at 9:43 AM on September 28, 2005

I want to know why 98 percent of the time I sneeze twice, but occasionally I sneeze about twenty times (triggered by coffee, dust, etc.) I never sneeze once.
posted by weapons-grade pandemonium at 9:54 AM on September 28, 2005

I have bright-light sneezing!

I think it's because the optic nerve passes immediately beside the nasal nerves. I should probably RTF link posted above, though...
posted by five fresh fish at 11:52 AM on September 28, 2005

I thought everyone did it. Until people started laughing at me.
posted by brautigan at 12:01 PM on September 28, 2005

I thought everyone sneezed from bright lights until I read this thread! I can't believe only 1/6 - 1/4 of the population has this. Weird...
posted by widdershins at 1:02 PM on September 28, 2005

Huh. I have this. I always thought it was because the blood vessels in the nose somehow expanded in the sunlight—that might not make complete sense, but that was a theory either I or my father came up with when I was younger.
posted by limeonaire at 1:16 PM on September 28, 2005

I've looked, and apart from the fact that it's heritable, there's no consensus on the exact mechanism that makes this happen. I think of it as nervous system crosstalk, like facial sweating and tearing when you eat spicy-hot food, or pelvic sweating while you are using the toilet or having sex, but that's just a pet theory, no data to back it up.
posted by ikkyu2 at 5:49 PM on September 28, 2005