Gesundheit!

[Standing Wolf]

Somewhere between 18 and 35% of all people are afflicted with something called autosomal dominant compulsive helio-opthalmic outbursts (ACHOO).

Sunlight makes you sneeze.

Apparently the phenomenon was first noted by Aristotle in the Fourth Century BC, and doctors and scientists have been theorizing about its cause ever since.

Today, scientific attention has mainly focused on a hypothesis proposed in 1964 by Henry Everett, who was the first to call light-induced sneezing “The Photic Sneeze Effect.” Since the nervous system transmits signals at an extremely fast pace, Dr. Everett hypothesized that the syndrome was linked to the human nervous system, and was perhaps caused by the confusion of nerve signals.^[23] The genetic basis of photic sneezing still remains unclear, and single genes for this condition have not been found and studied. However, the condition often occurs within families, and it has been suggested that light-induced sneezing is a heritable, autosomal-dominant trait.^[14] A 2010 study demonstrated a correlation between photic sneezing and a single-nucleotide polymorphism on chromosome 2."

https://en.wikipedia.org/wiki/Photic_sneeze_reflex

The "confusion of nerve signals" referred to above appears to entail the brain interpreting an optic reaction as nasal irritation.