Topical Guide 672
Mark Dorset
Health: Inherited Conditions: Photic Sneeze Reflex
What a Piece of Work I Am, Chapter 11:
It was another sunny day, and the whiteness of the building was dazzling. Ariane blinked into the glare and gleam of it. The brightness made her squint and wrinkle her nose and sneeze.
Wikipedia, “Photic sneeze reflex”:
The photic sneeze reflex (also known as Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome) is an inherited and congenital autosomal dominant reflex condition that causes sneezing in response to numerous stimuli, such as looking at bright lights or periocular (surrounding the eyeball) injection. The condition affects 18–35% of the world’s population, but its exact mechanism of action is not well understood. […]
The photic sneeze reflex manifests itself in the form of uncontrollable sneezing in response to a stimulus which would not produce a sneeze in people without the trait. The sneezes generally occur in bursts of 1 to 10 sneezes, followed by a refractory period that can be as long as 24 hours. […]
A photic sneeze results from exposure to a bright light and is the most common manifestation of the photic sneeze reflex. This reflex seems to be caused by a change in light intensity rather than by a specific wavelength of light.
A survey conducted by the School of Optometry at the University of Alabama at Birmingham found that 67% of respondents who identified as photic sneezers were female and 94% were Caucasian. The study also found that photic sneezing was significantly more common in people with a deviated nasal septum.
Further studies have revealed this mechanism to be inherited. […]
There is much debate about the true cause and mechanism of the sneezing fits brought about by the photic sneeze reflex. [Non-photic sneezing] occurs in response to irritation in the nasal cavity, which results in an afferent nerve fiber signal propagating through the ophthalmic and maxillary branches of the trigeminal nerve to the trigeminal nerve nuclei in the brainstem. The signal is interpreted in the trigeminal nerve nuclei, and an efferent nerve fiber signal goes to different parts of the body, such as mucous glands and the thoracic diaphragm, thus producing a sneeze. The most obvious difference between a normal sneeze and a photic sneeze is the stimulus: normal sneezes occur due to irritation in the nasal cavity, while the photic sneeze can result from a wide variety of stimuli. […]
The photic sneeze effect has been documented for many centuries. The Greek philosopher Aristotle was one of the first to contemplate this strange phenomenon in 350 BCE, exploring why looking at the sun causes a person to sneeze in The Book of Problems: “Why does the heat of the sun provoke sneezing?” He hypothesized that the sun’s heat caused sweating inside the nose, which triggered a sneeze in order to remove the moisture. In the 17th century, English philosopher Francis Bacon disproved Aristotle’s hypothesis by facing the sun with his eyes closed, which did not elicit the ordinary sneeze response. Bacon therefore guessed that the eyes played a vital part in triggering photic sneezing. He assumed that looking at the sun’s light made the eyes water, and then that moisture proceeded to seep into the nose and irritate it, causing a sneeze. Although plausible, scientists later determined this hypothesis to also be incorrect because sun-induced sneezing occurs too quickly after sunlight exposure; watering of the eyes is a slower process, so it could not play a vital part in triggering the reflex.
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