Why Do My Eyes Close When I Sneeze?

Ah, the elusive achoo—there's much mystery surrounding our sternutation reflex, a.k.a. the sneeze.

Sneezing protects our nasal passageways from foreign particles by forcing a 100 mph whoosh of air from the lungs, but the reflex demands more movement than that. When stimulated, the brain stem’s sneeze center orders muscle contraction from esophagus to sphincter. That includes the muscles controlling your eyelids. Some sneezers even shed a few tears.

No one knows why. It's possible the body has grown to associate protecting the nasal passageways with protecting the eye, or it may just be a result of our body’s wiring. Nor do scientists know why some people sneeze at bright lights, or why the reflex is pleasurable to some but not others. Whatever its workings, the sneeze has the distinction of being the only reflex that warrants a "bless you" from total strangers.

Why do we have Fever?

Fever occurs usually when a virus or bacteria invades the body. The immune system produces chemicals called pyrogens, which trick the brain's hypothalamus (where the body's thermostat resides) into sensing an artificially cool body temperature.

The brain responds like any good warm-blooded animals would, by knocking the thermostat up a few notches. Blood rushes to the body's core, heating the body overall but cooling the surface—hence the chills. The body's metabolic rate goes up and muscles contract.

The immune system's goal: to encourage chemical reactions that will increase production of disease-fighting antibodies, stimulate activity of white blood cells and even inhibit the invading microbe's growth.