Why Some People Sneeze at the Sun

Most of us think sneezing comes from irritants.

But for up to 1/3 of people, there’s another trigger hiding in plain sight: bright light.

Step outside into the sun, stare into a flashlight, or catch the burst of a camera flash, and suddenly, you sneeze.

This is called photix sneezing. The scientific name is:

Autosomal dominant compelling helio-ophthalmic outburst syndrome.

Fittingly, the acronym spells ACHOOs.

It’s not dangerous, but it is genetic. If one parent sneezes at sudden light, about half of their children will, too.

Some studies even suggest people with this reflex tend to have above-average intelligence.

Why does it happen?

The exact mechanism isn’t fully understood, but here’s the leading theory: when intense light floods the eyes, the optic nerve fires a signal to constrict the pupils.

Because the optic nerve sits so close to the trigeminal nerve — which governs facial sensation — some of that electrical signal “bleeds over,” confusing the brain into thinking there’s an irritant in the nose.

The result is a sneeze.

Ancient philosophres noticed it, too — Aristotle thought it was because of the sun’s heat.

A reminder

Even small quirks in our biology can reveal big truths.

What looks like an odd reflex might be unique brain wiring. Just because something is common doesn’t mean it’s meaningless.

So next time you or someone you know sneezes at the sun, remember: it’s not just coincidence.

It’s genetics, it’s neurology — and it might even be a sign of how extraordinary the human body really is.

Until next time,

Kashif Khan

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