Have you ever stepped out into the sun after a long day of sitting inside and suddenly felt the urge to sneeze?
Usually, sneezing is caused by irrigation in the nose, but how does the sun irritate your nose? This phenomenon is called the photic sneeze reflex. The cross-wire between the visual pathway and the sneezing pathways of your brain and nose could be caused by the sudden exposure to bright light.
This has also recently been named the ACHOO syndrome and has been seen in some genetically predisposed families. It is a polygenic trait that has been seen on the ZEB2 regions of chromosome 2 and 3. This area is involved with the development of the nervous system so any changes will cause the cross-linked reaction that we see in the ACHOO syndrome. Robust associated at these locations also indicate that the mutation is seen across multiple populations and ethnic groups.
Overall, the sun doesn’t directly “cause” you to sneeze, but rather triggers a chang within the visual and trigeminal response pathway. We still do not know how light can become a sneeze signal so quickly, especially considering this is not the average path for light input in the nervous system. Is the cortex driving this system or simply modulating it?
There is still so much more to learn about this reflex. Keep this in mind next time you step outside and feel your nose start to twitch!
References
Songu, M., & Cingi, C. (2009). Sneeze reflex: facts and fiction. Therapeutic Advances in Respiratory Disease, 3(3), 131-141.
Whitman, B. W., & Packer, R. J. (1993). The photic sneeze reflex: literature review and discussion. Neurology, 43(5), 868-868.
