Do you always close your eyes to sneeze?
We’ve all had them, those apocalyptic sneezes that leave you afraid to open your eyes and survey the damage in case you see a lung stuck to the far wall. Janine Rouse wonders if we must always close our eyes to sneeze. The answer is yes, if it’s a genuine sneeze.
Though our ancestors read a lot into sneezes we don’t usually give them a second thought. There are times, though, when sneezing isn’t so innocent. If you sneeze while driving you can crash, and for photic sneezers — people who sneeze in sudden bright light — this can be a real hazard. In the age of the global pandemic it would be nice if there was a way to suppress sneezing. And there’s always hay fever.
These kind of things have provoked mild interest in the mechanism behind sneezing, though it is not thoroughly understood yet. There is almost certainly a sneeze centre in the brainstem. We’ve found it in cats and strongly suspect it in humans. This receives stimulation from a variety of irritant detectors in the nasal passages. When this stimulation is sufficient then the sneezing reflex goes to work — a coordinated response where the eyes close, air is sucked in to the lungs and then explosively vented perhaps as fast as 85% the speed of sound.
Closing the eyes is part of the reflex. It’s even used as one of the criteria to tell real sneezes from the imitations produced in a rare psychological disorder. These fake sneezes aren’t always accompanied by closed eyes and generally eject very little of anything from the nose. They are just the cerebral cortex putting on a show, not the cataclysmic whoppers generated by the brainstem.
The sneezing reflex is complicated but thankfully it comes wired in because the manual would be thick and full of incomprehensible diagrams. If it existed then somewhere towards the front would be a bold instruction in red: CLOSE YOUR EYES.