What Is A Photic Sneeze?
Sneezing is a common reaction that forces air through the nose and mouth. When the tissues of the nasal cavity are irritated, sneezing is an act that helps clear the cavity. This is a reaction that cannot be controlled and results in an explosive sound too.
Some people sneeze when they are suddenly exposed to a light source.
Reflexive sneezing that is induced by sunlight or other bright lights is called photic sneeze reflex.
Experts say that the photic sneeze reflex causes sneezing when people experience variations in the intensity of light.
Photic sneeze reflex is also called photosneezia or Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome.
About 10-35% of people in the world suffer from photic sneeze reflex.
White women seem to be at more risk for developing photic sneeze reflex. A study amongst 367 patients reported that 94.3% of photic sneezers were Caucasian (white) individuals and 67% of them were women. This study also mentioned that 90.7% of these individuals had three or lesser sneezes on sudden exposure to light. Only 12.3% of people had continuous reactions on exposure to light.
Symptoms of Photic Sneeze
The primary symptom of photic sneeze is sneezing when exposed to light. Most individuals don’t have extended reactions to light. They only react when they suddenly move from a dark space to a lit space. The number of sneezes ranges from 1-10.
How Does Genetics Influence Photic Sneeze?
ZEB2 Gene
The ZEB2 gene helps make a protein that plays a role in forming the nerve cells before birth. This protein is also important in making vital parts of the body like the kidneys and skeletal muscles.
rs10427255
The rs10427255 SNP is located near the ZEB2 gene. The minor C allele is the risk allele of this SNP and is associated with an increased risk for developing photic sneeze reflex.
Non-Genetic Influences on Photic Sneeze
Deviated nasal septum - The nasal septum is the thin wall that gives structure to your nose. Some people’s nasal wall gets displaced or moves from the original place because of certain injuries. The risk for developing photic sneeze is high in people with a deviated nasal septum.
Use of tobacco - A certain study relates the use of tobacco with light-induced episodes of sneezing.
Optic nerve response - Some scientists believe that when the optic nerve is exposed to sudden light sources, it creates similar reactions in the body, like when the nose is irritated. This can cause episodes of sneezing.
Eye injections - In some cases, people end up having photic sneezing when they are given eye injections. These injections trigger the trigeminal nerve. This is one of the cranial nerves that give sensations to the various parts of the face. Triggering the nerve causes sneezing.
Prominent corneal nerves - According to a small study conducted, 67% of people with some degree of prominent corneal nerves experienced photic sneezing.
The Pesky Effects Of Photic Sneeze
- More than being risky, people consider photic sneezing a discomfort or an annoyance. It can turn dangerous in a few situations.
- If you are driving out of a dark tunnel and start sneezing on exposure to sunlight, it can result in accidents.
- People who operate heavy machinery also need to know to manage the condition to prevent injuries in case of sudden sneezing.
- When you sneeze, up to 40,000 microscopic particles spew out from the nose. If you have a cold or the flu, you can infect others around you because of photic sneezing.
Recommendations To Manage Photic Sneeze
Cover your eyes - When you are stepping out in the sun, wear sunglasses to prevent direct exposure to sunlight. This is a very easy trick to prevent the flaring up of sneezes. You can also wear hats and scarves to bring down the intensity of sunlight.
Philtral Pressure Technique (PPT) - When you apply pressure to the sub-philtral region, it is said to help stop sneezing. The philtrum is the region between the nose and the upper lips. When you press this region gently with the index finger, this brings down the urge to sneeze.
When you press the philtrum region, this stimulates the mechanoreceptors. These receptors send signals to the brain when stimulated by an external medium (touch, in this case). These mechanoreceptor signals override the signals caused by trigeminal nerve stimulation and hence prevent sneezing.
Antihistamine sprays and drugs - Even though photic sneeze is not an allergic reaction, it seems to get better with antihistamine sprays and drugs.
Summary
- Photic sneeze reflex is a condition that causes people to sneeze when they are exposed to sudden light sources. Sunlight, flashlights, and other sources of lights that fall on a person suddenly can cause photic sneezing reflex. This reflex results in sneezing when the person is exposed to varying intensities of light.
- Photic sneeze reflex is also called Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome or photosneezia.
- A majority of people (about 90%) experience 1-10 sneezes when they come in contact with sudden light. They become alright after that. For some people, the reflex reaction can be prolonged and continuous.
- The C allele of the rs10427255 SNP located near the ZEB2 gene increases a person’s risk for developing photic sneeze.
- Some experts mention that triggers to the optic nerve results in an ‘allergy-like’ reaction in the body, causing sneezing.
- Protecting the eyes with sunglasses while stepping out and using antihistamine sprays and drugs can help manage photic sneeze reflex.
References
https://www.bbc.com/future/article/20150623-why-looking-at-the-light-makes-us-sneeze
https://pubmed.ncbi.nlm.nih.gov/7673597/
https://www.healthline.com/health/photic-sneeze-reflex#risks
https://www.nature.com/articles/s41433-019-0368-4
https://www.nature.com/articles/s41598-019-41551-0
https://www.pbs.org/newshour/science/does-the-sun-make-you-sneeze
https://medlineplus.gov/genetics/gene/zeb2/
https://www.snpedia.com/index.php/Rs10427255
