Why does looking at bright light triggers sneezing in some people? Are there any recent studies that have found a cause for this Photic sneeze reflex? The Wikipedia article only references studies pertaining to the effect, stating that the cause is unknown. The article also states that "the condition affects 18-35% of the population", which seems to be quite a large percentage - what could have lead to the development and persistence of such a genetic trait in humans - are there any evolutionary advantages to this?
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You are talking about the photic sneeze reflex.
The mechanisms are not entirely understood, but it affects 18-35% of the population.
According to Wikipedia (although this passage is not sourced):
And, it could be advantageous:
Also, anecdotally, as I too photosneeze, I can see an advantage: should the atmosphere become weaker in the future, and allow more light to enter than we are accustomed to, it would discourage looking directly at the sun.
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