Some people (up to 24% in one survey) tend to sneeze when they are exposed to bright light. A new name for this reflex is Autosomal Cholinergic Helio-Ophtalmologic Outburst syndrome, or ACHOO for short. Har har. The same researchers who came up with this acronym compared EEGs of people who sneezed as response to light and those who don't. The subjects also filled out a questionnaire designed to stimulate brain activity, and also to find out how much their noses tickled in response to light. Bursts of light accompanied the EEGs.
Could it possibly be that some people are just more sensitive than others? Link
You can see the red line above showing the photo sneezers had much higher nose-tickle response to bright light, and showed stronger activity in the somatosensory cortex, an area that processes sensory information. So it appears that people with ACHOO Syndrome have higher sensory responses to both the tickle sensation and to the visual stimulus of the bright light.
Unfortunately, they weren't able to come up with a connection between the two areas and a sneeze reflex center (we're not that good yet), but it's certainly a first step, and the hypothesis is that the insula, may link the areas, though other pathways could exist as well (the insula is totally everyone's favorite brain area right now, ain't it?).
Could it possibly be that some people are just more sensitive than others? Link
I sneeze in bright sun, but it's not a constant thing. In sunlight I always *want* to sneeze when I first see it, but unless I'm looking directly at the sun, I rarely do.
so it makes sense to me that there are varying degrees of sensitivity.
Also note that it always makes me sneeze twice, and after that the light no longer affects me for more than half an hour.
That makes sense since I can blow air out of my eyes.