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why do we sneeze when we look at the sun

Have you ever emerged from a matinee movie, squinted into the sudden burst of sunlight and sneezed uncontrollably? Up to a third of the population will answer this question with an emphatic Yes! (whereas nearly everyone else scratches their head in confusion). as the result of being exposed to a bright light known as the is a genetic quirk that is still unexplained by science, even though it has intrigued some of history's greatest minds. mused about why one sneezes more after looking at the sun in The Book of Problems : Why does the heat of the sun provoke sneezing? He surmised that the heat of the sun on the nose was probably responsible. Some 2,000 years later, in the early 17th century,
neatly refuted that idea by stepping into the sun with his eyes closed the heat was still there, but the sneeze was not (a compact demonstration of the fledgling scientific method). Bacon's best guess was that the sun's light made the eyes water, and then that moisture ( braine humour, literally) seeped into and irritated the nose. Humours aside, Bacon's moisture hypothesis seemed quite reasonable until our modern understanding of physiology made it clear that the sneeze happens too quickly after light exposure to be the result of the comparatively sluggish tear ducts. So neurology steps in: Most experts now agree that crossed wires in the brain are probably responsible for the photic sneeze reflex.

A sneeze is usually triggered by an irritation in the nose, which is sensed by the trigeminal nerve, a cranial nerve responsible for facial sensation and motor control. This nerve is in close proximity to the optic nerve, which senses, for example, a sudden flood of light entering the retina. As the fires to signal the brain to constrict the pupils, the theory goes, some of the electrical signal is sensed by the trigeminal nerve and mistaken by the brain as an irritant in the nose. Hence, a sneeze. But because this harmless (albeit potentially embarrassing) phenomenon doesn't seem to be linked with any other medical condition, scientific study of the subject has been scarce. Research has done little more than document its existence and attempt to gauge its prevalence. No rigorous studies exist, but informal surveys peg 10 to 35 percent of the population as photic sneezers. A study in the 1960s showed that the trait is autosomal-dominant the gene is neither on the X nor Y chromosome and only one copy of the gene has to be present for the trait to be expressed so if one parent sneezes when they look at a bright light, about half of his or her children will, too. The genetic culprit remains unidentified, but scientists are starting to take an interest in trying to find out.

I think it's worth doing, says, a neurologist at the University of California, San Francisco, and an investigator at the Howard Hughes Medical Institute. Pt cek studies episodic disorders such as epilepsy and migraine headaches, and he believes that investigating the photic sneeze reflex could shed light on their related neurology. are sometimes triggered by flashing lights and migraine headaches are often accompanied by photophobia. If we could find a gene that causes photic sneezing, we could study that gene and we might learn something about the visual pathway and some of these other reflex phenomena, Pt cek says. But until he and his colleagues find the right families for their study, the photic sneeze reflex will remain something of a genetic novelty act, like the ability to roll your tongue. Although a 1993 paper in the journal Military Medicine raised concerns that light-induced sneezing might endanger fighter pilots, for whom a split second of lost vision could be lethal in certain situations, such fear was largely put to rest when a small study found that wearing sunglasses eliminated the effect. Beyond that blip of gravitas, papers published about photic sneezing have largely leaned toward the whimsical end of the spectrum.

Consider one 1978 publication that took advantage of the then-raging acronym fad and suggested an alternate name for the photic sneeze reflex: Autosomal-dominant Compelling Helio-Ophthalmic Outburst syndrome, or, of course, ACHOO. ^ Laura Dean, MD. Ncbi. nlm. nih. gov. Retrieved. Roberta A. Pagon (Nov 18, 2002). Scientific American. ^ Breitenbach RA, Swisher PK, Kim MK, Patel BS (December 1993). "The photic sneeze reflex as a risk factor to combat pilots". Military medicine. 158 (12): 8069. P. Semes LP, Amos JF, Waterbor JW (June 1995). "The photic sneeze response: a descriptive report of a clinic population". J Am Optom Assoc. 66 (6): 3727. P. Abramson DC (Aug 1995). "Sudden Unexpected Sneezing During The Insertion Of Peribulbar Block Under Propofol Sedation". Canadian Journal of Anesthesia. 42 (8): 7403. :. Raphael G, Raphael MH, Kaliner M (1989). "Gustatory rhinitis: a syndrome of food-induced rhinorrhea". J. Allergy Clin. Immunol. 83 (1): 1105. :. P. Hall JG (Apr 1990). "The Snatiation Reflex". Journal of Medical Genetics. 27 (4): 275. :. Teebi AS, Alsaleh QA (Aug 1989). "Autosomal Dominant Sneezing Disorder Provoked by Fullness of Stomach". Journal of Medical Genetics. 26 (8): 539540. :. CS1 maint: Uses authors parameter ( Cole EC, Cook CE (Aug 1998). "Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies".

Am J Infect Control. 26 (4): 45364. :. P. ^ Ahn ES, Mills DM, Meyer DR, Stasior GO (Jul 2008). "Sneezing reflex associated with intravenous sedation and periocular anesthetic injection". 146 (1): 3135. :. CS1 maint: Uses authors parameter ( ^ Abramson DC (1995). "Sudden Unexpected Sneezing During The Insertion Of Peribulbar Block Under Propofol Sedation". Canadian Journal of Anesthesia. 42 (8): 740743. :. Western Journal of Medicine. 146 (5): 20. 1 May 1987. P. Allergies. about. com. 2013-05-12. Retrieved. Right Diagnosis: Symptoms, Diagnosis, Treatments and Causes. Health Grades Inc. Retrieved. , Aristotle, exclassics. com ^, Karen Schrock, ScientificAmerican. com, January 10, 2008. Blitz, Matt. Today I Found Out. Vacca Foeda Media. Retrieved. Everett, Henry C. (May 1964). "Sneezing in Response to Light". Neurology. 14 (5): 483490. :. Peroutka, S. J. ; Peroutka, L. A. (1984). " ". New England Journal of Medicine. 310 (9): 599600. :. P. Eriksson N, Macpherson JM, Tung JY, Hon LS, Naughton B, Saxonov S, Avey L, Wojcicki A, Pe'er I, Mountain J (2010). Gibson, Greg, ed. PLoS Genet. 6 (6): e1000993. :. P. CS1 maint: Multiple names: authors list (

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