The reason sneezing causes people to blink

The sneeze, an automatic response to many stimuli, has engendered numerous myths and fairy tales. Among these is that if you sneeze with your eyes open, your eyes will pop out of your head. As silly as this might sound to some, it is due to the realization that a sneeze is so explosive. A sneeze sends particles out of the nose at the rate of up to 100 miles per hour. In truth, if you could manage to keep your eyes open, there would be no ill effects.

The blood pressure behind the eyes does increase during a sneeze, as the body tries to concentrate all related muscles into the process of expelling any unwelcome invader to the nose.

Sneezing (sternutation) results from nerve transmissions to and from an area of the brain called the sneeze center. The sneeze center coordinates diaphragm, chest, abdominal, vocal chord and eyelid muscles to achieve the sneeze and rid the nasal passages of irritants. The involvement of the vocal cord muscles can be seen in a person who has suffered a series of allergic sneezes and ends up with a sore throat. The eyelids sometimes evidence the pressure by releasing tears. Part of the nervous system involved is the ophthalmic nerve, which is near the eye and the maxillary nerve, which serves the sinuses. Since these parasympathetic nerve bundles tend to generalize to nearby nerves, the relationship to the eyes is probably not a direct need for the evoking of a sneeze.

Another relationship to the eyes is called photic sneezing, which occurs in about one quarter of the human population, when exposure to a bright light such as the sun causes sneezing. Since sun glasses or hats that shade the eyes can prevent the sneezing, it is assumed that the ophthalmic nerve is being stimulated.

The ophthalmic nerve is a branch of the trigeminal nerve, which runs along the eye. This type of “reverse” effect can also be exemplified by a sneeze which occurs when a person is plucking her eyebrows.

Most people are aware of the superstition that evil demons are possessing the body and when a person sneezes he is expelling these evildoers. Hence the expression “God bless you.” This comes from somewhere around the Middle Ages. But sneezing myths existed long before that, being recorded as early as 401 BC.

In the Odyssey, Odysseus’ wife Penelope was fending off suitors. When she heard that Odysseus might be alive, she vowed that he and his son would take revenge on the suitors. Just then his son sneezed, and Penelope saw that as a sign from the gods.

If this is true, the gods are also with the animal kingdom. Animals are known to sneeze, with the “sneeziest” probably being the iguana. Iguanas sneeze more often and more productively than any other animal in an attempt to rid their bodies of salts created during their digestion cycle. And their eyes, while quite mobile, are still set in their heads