Sneezing, photic and otherwise (update)

Update, 10.16.10:  From Mr. Science podcast, an entire episode (about 3o minutes) with an interview of an expert on photic sneezing,  Professor Louis Ptáček : Ep 135: Why do I sneeze at the Sun?

Also, the following reference:

Langer N, Beeli G, Jäncke L, 2010 When the Sun Prickles Your Nose: An EEG Study Identifying Neural Bases of Photic Sneezing. PLoS ONE 5(2): e9208. doi:10.1371/journal.pone.0009208

Reprint of post originally published June 24, 2009:


Do you sneeze when you suddenly go into bright light?

Certain members au château Swivelchair do this, and it is called a “photic sneeze“.

It has to do with electrical charge crossing over from the neural wiring for the eye to the one related to the nose.  Apparently, overstimulating the optic nerve triggers the trigeminal nerve nuclei pathways.

I don’t think anyone really knows the precise neural pathway, although here is an excellent blog post from A.E. Brain.  For a great Scientific American article and reader comments, see here.   SciAm also published an expert comment .

The photic sneeze reflex is  of course preventable with sunglasses.  There is a photic sneezing support group.

Photic sneezing is hereditary. [Update: Not proven to be hereditary, according to Prof. Ptáček, but his group is collecting DNA samples if you would like to donate]. Go to the movies during the day and watch the families come out from the dark theater into the bright afternoon light.  You can see which family members have photic sneezing.  (Anecdotally, it seems to segregate out with redheads at the movie theaters in the malls around these parts, so I wonder if there’s a melanin/neuromelanin angle to this. I mean, from what I hear from my horribly rude friend who stares at families coming out of matinees to see who has photic sneezing ).

Low level electrical stimulation up the nose can cause a sneeze — this was first reported in cats, and later in a 3-person healthy human study.    On the sneeze-reflex and its control. In this study, the electrically-stimulated sneeze reflex also was reversed by an anesthetic to the mucus membranes. Therefore, one would think that among its many benefits to the fine citizens of Los Angeles,  Botox could also prevent sneezing one might later regret.

You scoff now. But if you are being driven by a photic sneezing relative and you are on one of those cell-phone deadening canyon roads  in LA, with straight up on one side, and straight down on the other, botox up the nose to prevent photic sneezing seems totally reasonable.  Particularly when les lunettes de soleil sont disparu at the beach.

The thought is that figuring out photic sneezing will be instrumental in figuring out  and preventing seizure-related conditions. Perhaps the best known photic-induced conditions are in the migraine – epileptic seizure spectrum.  In fact, one can even get “Flicker illness” when being medi-vac’d because helicopters produce 24-27 flashes per second.  Flicker illness: an underrecognized but preventable complication of helicopter transport.

OK. Have you ever sat down next to someone in a public place and had them start sneezing? Run.  Sneezing induced by sexual ideation or orgasm: an under-reported phenomenon. On the other hand, an eroto-sneezing significant other could be a bonus — the equivalent to wearing one’s heart on one’s sleeve,  so to speak.  Maybe there’s an evolutionary advantage in that.

(This post is categorized under “synesthesia” because it relates to crossing neural wiring resulting in involuntary behavior from sensory input.)