Photic sneeze reflex is a genetic autosomal dominant trait, which causes sneezing when exposed suddenly to bright light, possibly many times consecutively. Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is A sneeze (or sternutation) is a semi-autonomous Convulsive expulsion of Air from the Lungs, most commonly caused by foreign particles It is also referred to as photic sneeze response, sun sneezing, photogenic sneezing, the photosternutatory reflex, being photo sensitive, ACHOO syndrome, and "Achooism," with its related backronym Autosomal dominant Compelling Helio-Ophthalmic Outburst syndrome. A backronym (or bacronym) is a Phrase that is constructed "after the fact" from a previously existing word or Abbreviation, the abbreviation The condition affects 17 to 35 percent of humans. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus
The first mention of the phenomenon is probably in the later work attributed to Aristotle (Problems, book XXXIII). Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great.
The probable cause is a congenital malfunction in nerve signals in the trigeminal nerve nuclei. A congenital disorder is a disease or disorder that is present at birth A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The sensory trigeminal nerve nucleus is the largest of the Cranial nerve nuclei and extends through the whole of the Brainstem, Midbrain to medulla The fifth cranial nerve, called the trigeminal nerve, is apparently responsible for sneezes. Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex. The optic nerve, also called cranial nerve II, is the Nerve that transmits visual information from the Retina to the Brain. The trigeminal nerve (the fifth Cranial nerve, also called the fifth nerve or simply V) is responsible for sensation in the face
Another theory suggests that tears leaking into the nose through the nasolacrimal duct are a cause of the photic sneeze reflex. The nasolacrimal duct (sometimes called tear ducts) carries Tears from the Lacrimal sac into the Nasal cavity. The speed of the reflex seems to favor the first theory, as it happens much too quickly for tears to be generated and drain into the nose. In addition this sneeze reflex can be brought on by a sudden inhaling of cold air or a strong flavor such as a strong mint gum. This implies an overstimulation of any nerve close to the trigeminal nerve can cause the sneeze reflex.
While this phenomenon is poorly understood, recent research has shown that antihistamines being used to treat rhinitis due to seasonal allergies may also reduce the occurrence of solar sneezes in those people suffering from both conditions. A histamine antagonist is an agent which serves to inhibit the release or action of Histamine. Rhinitis is the medical term describing irritation and inflammation of some internal areas of the Nose.