Sneezing is a reflex that protects us from irritants or foreign particles that might otherwise get into our lungs. When you sneeze, it’s because sensory receptors in the nose are activated by a pollutant, an allergen such as pollen or dust, or other particles. The activated receptors then send signals to the brain, specifically the brain stem. The sneeze expels mucus along with the irritants.
There have been reports of sneezing causing physical problems. For example, Major League baseball player Sammy Sosa sprained his back after sneezing violently, and, as a result, missed a month of games. Other injuries that have reportedly resulted from sneezing especially forcefully, or from holding back a sneeze, include stroke, miscarriage, car accidents, broken blood vessels in the white of the eye, retinal detachment, and fainting—but most of these are quite rare.
The strength, sound, and volume of a sneeze have to do with many factors, including anatomical and physiological differences among people, such as the strength of abdominal muscles, lung volume, and size of the windpipe or trachea, as well as the amount of air inhaled and whether most of the sneeze is expelled through the mouth or the nose (the mouth is louder). Interestingly, one survey found that many people report they sneeze differently in private vs. in public.
It’s really a blink and it's part of the many coordinated movements that are part of the involuntary reflex of sneezing. It’s also theorized that the eyes blinking or briefly closing is a biological adaptation—a way to shield them from whatever irritants are being expelled during the sneeze.
It may depend on what it takes to clear the nose of contaminants as well as individual variations in the sneeze reflex. In one lab study, researchers found that nasal cells from people with sinusitis didn’t respond to a sneeze in the same way as those of healthy people. It's possible that sneezing doesn't completely clear the nasal passage in people with sinusitis, which in theory might lead them to sneeze multiple times.
Yes, there have been reports of extending bouts of sneezing. There was a case of a young girl who sneezed more than 200 times in 20 minutes, and a teen boy who sneezed three to six times a minute for more than a month. According to Guinness World Records, the longest sneezing fit ever recorded was a 12-year-old girl who sneezed about a million times over a year and only stopped sneezing after more than 2.5 years.
The velocity can vary based on the size of the body frame of the person sneezing. Some reports clock a sneeze as hurling particles at up to 100 mph. Others, however, suggest it's considerably less. A small study in PLOS ONE showed the maximal velocity may be 10 mph. The distance particles can be propelled could be as far as 20 or so feet, depending on factors that include the weight and size of the expelled particles.
Yes. Sneezing is a respiratory reflex that consists of two parts: the first involves something irritating sensory receptors in the nose. The second involves inhaling deeply, closing or blinking your eyes, then exhaling explosively. You may be able to stop the reflex during the first part by, for example, putting a finger under your nose, but once you inhale, there’s no turning back.
Genetics determines the “photic sneeze reflex,” also known as sun sneezing or the “ACHOO syndrome” (autosomal-dominant compelling helio-ophthalmic outburst). The tendency runs in families and may affect up to 35 percent of people. Scientists attribute it to a crossover of nerve signals such that when bright light stimulates the eye's optic nerve, it also stimulates the nerve responsible for the sneeze reflex.
Despite popular belief, your heart does not stop when you sneeze. This myth may have its origins with people feeling that their heart “skipped a beat” when they sneezed. That occurs because of changes in the internal pressure in the chest cavity, which can, in turn, alter heart rhythm.