Support for LAist comes from
Audience-funded nonprofit news
Stay Connected
Audience-funded nonprofit news
Listen

Share This

KPCC Archive

Why does the sun make some people sneeze?

Does this picture make you feel sneezy?
Does this picture make you feel sneezy?
(
Sanden Totten / KPCC
)

With our free press under threat and federal funding for public media gone, your support matters more than ever. Help keep the LAist newsroom strong, become a monthly member or increase your support today . 

If your find yourself succumbing to a sneeze — or a fit of sneezes — as you stare up into the sunlight, you might be among those suffering from a rare, but benign, syndrome.

It's not an allergy to the sun and it's not a cold.

It's the photic sneeze reflex, or Autosomal dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome.

While it may be annoying, it's also a very real phenomenon and relatively rare.

Support for LAist comes from

The human body has all sorts of reflexes — your stomach expands when you eat; if you touch a hot stove, you move your hand away; your pupils dilate when it's dark.

Likewise, sneezing is a reflex that we've developed to help clean out our airways.

If an irritant, like pepper or pollen or dust gets in our nose, the phrenic nerve tells the diaphragm to contract and vigorously expel air. We call that a sneeze.

For people who have photic sneeze reflex, sneezes are triggered not only by irritants, but also by bright light.

So why does this reflex exist? Even though it's a question that's been posed for millennia (Aristotle wondered about sun-triggered sneezing in his "Book of Problems"), scientists still aren't sure.

There is some concern that photic sneeze reflex could cause problems for drivers or pilots, but for the most part it's believed to be harmless.

Support for LAist comes from

Louis Ptacek, a neurologist and human geneticist at University of California, San Francisco, has looked into photic sneeze reflex. He thinks it can help us better understand epilepsy and other movement disorders.

Ptacek has found that photic sneeze reflex is genetic and that it runs in families.

"If I have photic sneeze reflex, there's a 50/50 chance that each child will inherit the gene from me," Ptacek said.

If you're one of those who finds themselves sneezing at the sun, you may think it's a common reaction.

You might exhort your friends to look at the light to help them sneeze. But you're actually in the minority — only 10 percent of people have this reflex.

"It doesn't seem to have any benefit as pulling our hand away from hot stove does," said Ptacek. "We know that if some patients with epilepsy are exposed to a flashing strobe light, that can induce seizure. It is my thought that if we can find out what causes photic sneeze reflex it might teach us about some of these other reflex phenomena."

For more from Brains On, the SCPR science podcast for kids and curious adults, you can subscribe in iTunes or wherever you listen to podcasts.

At LAist, we believe in journalism without censorship and the right of a free press to speak truth to those in power. Our hard-hitting watchdog reporting on local government, climate, and the ongoing housing and homelessness crisis is trustworthy, independent and freely accessible to everyone thanks to the support of readers like you.

But the game has changed: Congress voted to eliminate funding for public media across the country. Here at LAist that means a loss of $1.7 million in our budget every year. We want to assure you that despite growing threats to free press and free speech, LAist will remain a voice you know and trust. Speaking frankly, the amount of reader support we receive will help determine how strong of a newsroom we are going forward to cover the important news in our community.

We’re asking you to stand up for independent reporting that will not be silenced. With more individuals like you supporting this public service, we can continue to provide essential coverage for Southern Californians that you can’t find anywhere else. Become a monthly member today to help sustain this mission.

Thank you for your generous support and belief in the value of independent news.

Chip in now to fund your local journalism
A row of graphics payment types: Visa, MasterCard, Apple Pay and PayPal, and  below a lock with Secure Payment text to the right
(
LAist
)

Trending on LAist