ACHOO Syndrome: Why Bright Light Makes Some People Sneeze

It runs through my mom’s side of the family, I have it, and my children have it too. No, I’m not talking about The Force, young Padawan. I’m talking about why bright sunlight makes me sneeze like an excited Ewok.

For years, I just thought it was one of those strange little things my family did. Walk out of a dark building into bright sunshine and—ACHOO! Sometimes one sneeze, sometimes several. Apparently, we inherited more than family stories, personalities, and a resemblance around the eyes.

It turns out there is actually a name for this: the photic sneeze reflex, commonly called ACHOO syndrome.

And yes, ACHOO really is an acronym. Somebody in the scientific world clearly had a sense of humor.

So what exactly is ACHOO syndrome, why does bright light make some of us sneeze, and why does it seem to run through families like mine? The science is a little more complicated than the old “one dominant gene” explanation—but the family connection is very real.

Watch: Why bright light makes some people sneeze

What Is ACHOO Syndrome?

ACHOO stands for Autosomal Dominant Compelling Helio-Ophthalmic Outburst. That sounds less like a sneeze reflex and more like something a comic-book villain might unleash, but it refers to sneezing triggered by sudden exposure to bright light.

The reflex clearly tends to run in families, which certainly matches my experience. Older medical literature often described photic sneezing as an autosomal dominant trait, but newer genetic research suggests the story may be more complicated. Researchers have identified several genetic regions associated with the reflex, and the exact inheritance pattern is still being worked out.

In other words, seeing it show up across generations in a family is not unusual—but I would not start calculating everybody’s sneeze odds at Thanksgiving dinner just yet.

Why Does Bright Light Make You Sneeze?

Scientists still do not know exactly why bright light triggers a sneeze in some people. One longstanding theory involves interaction between visual signals and the trigeminal system involved in facial and nasal sensation. Other research has found differences in visual-cortex excitability and activity in areas involved with bodily sensation.

Translation: something about the way the brain processes that sudden blast of light appears to set off the sneeze machinery—but scientists are still figuring out exactly how.

So the old “crossed wires” explanation is still a useful way to picture one possibility. It just should not be mistaken for a completely settled answer.

How Common Is the Photic Sneeze Reflex?

You are not as unusual as you might think. Studies vary, but roughly one person in four appears to experience some form of photic sneeze reflex.

That is a lot of people walking out of movie theaters, restaurants, offices, or tunnels and immediately discovering that the sun has opinions about their nasal passages.

People with ACHOO syndrome also often sneeze more than once. That brings me to an important rule of sneeze etiquette: if someone is clearly in the middle of a sneeze salvo, you might want to wait until the entire symphony is over before saying “bless you.” Otherwise, you could be trying to squeeze three blessings between sneezes four, five, and six.

Can ACHOO Syndrome Be Dangerous?

Usually, ACHOO syndrome is more amusing or annoying than dangerous. The main concern is timing. An unexpected sneeze can be a problem if it happens while driving, operating machinery, or doing anything else where a split-second distraction matters—especially when moving suddenly from darkness into bright sunlight.

If bright light reliably triggers you, being aware of it helps. Sunglasses can reduce the sudden intensity of the light for some people. And if your sneezing suddenly changes, becomes severe, or comes with other symptoms, it is sensible to check with a qualified medical professional rather than assuming every sneeze is just ACHOO doing its thing.

Why Do We Say “Bless You”?

Nobody seems to have one definitive origin story for saying “bless you” after a sneeze. One tradition connects it with plague-era prayers for protection. Other explanations go back to older beliefs about sneezing, spirits, and the soul.

Whatever the origin, ACHOO families should probably establish an additional rule: wait until the sneezing has actually stopped.

So, the next time you see someone unleash a sneeze salvo, hold off on the blessings until the entire symphony is complete. After all, a comfortable sneeze is a successful sneeze!

Living With ACHOO Syndrome

Sunglasses are your friend. If bright sunlight sets you off, sunglasses can sometimes help reduce the trigger. And before anyone gets any ideas, no, my tendency to sneeze in bright sunlight has not converted me to the dark side of Daylight Saving Time.

I still support permanent Standard Time. The science of our body clocks is stronger than my sneeze. Standard Time keeps morning light better aligned with our natural circadian rhythms, while year-round Daylight Saving Time would push winter sunrise even later.

So yes, bright sunlight may make me sneeze like a Jawa on Tatooine, but that still doesn’t mean I want sunrise pushed an hour later. That’s where I draw the line in the sand.

Embrace the weird. This is a fun family quirk, a conversation starter, and one of those reminders that human bodies do some wonderfully strange things.
Carry tissues. Because, well, you never know when a family sneeze attack might be triggered.
Give yourself a second when moving into bright light. If you know the transition from dark to bright is a reliable trigger, a little awareness can keep the sneeze from catching you at the worst possible moment.

A Family Trait I Can Laugh About

For me, ACHOO syndrome is mostly one of those funny little reminders of family connection. My mom’s side has it, I have it, and my children have it. Apparently we pass down more than stories and family resemblance.

Sometimes we pass down a tendency to walk into the sunshine and immediately start sneezing.

There are worse family traditions.