I never heard of sneezing due to bright lights. I have come out of many theaters, and
do not remember ever hearing a sneeze. So I have learned something. I found a site
with quote from a small "peer-reviewed quarterly journal", from which I took a pertinent
quote:
"The mechanism of the bright light sneeze reflex seems to be an association of optic nerve
fibers and trigeminal nerve nucleus in the mid-brain. The trigeminal nerve's second division
supplies sensory fibers to the nasal mucosa. It is postulated that nerve impulses travelling
up the optic nerve will cause a sympathetic discharge down the trigeminal nerve fibers.
Another mechanism postulates that partial squinting of the eyes resulting from the
bright light causes squeezing of the lacrimal sac which results in tears running down the
nasolacrimal duct into the nasal cavity, causing stimulation ofthe nasal cavity and a sneeze. "