Why do some people sneeze if they look at the sun or other bright light sources?

According to Naked Scientist Chris Smith at least 20% of the population suffers from what is called the photic sneeze reflex - "sun sneezing".

While there is no exact explanation for it, Smith says the original theory is that this occurs because when you look at bright lights, it makes your eyes water, the watering makes your nose run and that tickles your nose and makes you sneeze.

He says it can be genetic.

The alternative explanation that we are comfortable with is that when light shines into the eye, the same circuits that are involved in making your pupil change size - that circuitry, some of it spills over in the brain stem into adjacent circuits which are involved in sneeze reflexes.

Chris Smith, Naked Scientist

In people that have that miswiring, when they look at a bright light the activity facilitates or increases the activity temporarily in the sneezing circuits in the back of your brain stem and that then moves you closer in the threshold for having a sneeze.

Chris Smith, Naked Scientist

About one person in five has this.

Chris Smith, Naked Scientist

Click on the link below to hear more science questions...


Recommended

by NEWSROOM AI
Read More
'HR people do not make hiring decisions, it is line managers'

'HR people do not make hiring decisions, it is line managers'

Human capital development executive Edith Leeuta says organisations have not clearly defined what an entry-level job is.

Despite losing, Banyana Banyana did a great job, says Eusebius

Despite losing, Banyana Banyana did a great job, says Eusebius

Callers to the Eusebius McKaiser show say Safa is to blame for the poor performance of the SA women's football team.

A new book describes the life and journey of Fatima Meer

A new book describes the life and journey of Fatima Meer

Professor Shireen Hassim discusses 'Voices of liberation: Fatima Meer' with 702's Eusebius McKaiser.

[LISTEN] How dire is the state of public schools in the country?

[LISTEN] How dire is the state of public schools in the country?

Equal Education head of research Hopolang Selebalo says KwaZulu-Natal, Eastern Cape and Limpopo schools still use pit latrines.

Even if Zindzi was not an ambassador you would still be touched, says Eusebius

Even if Zindzi was not an ambassador you would still be touched, says Eusebius

Eusebius McKaiser reflects on the tweets by Zindzi Mandela on the land issue, sparking a debate.

[LISTEN] 'Status anxiety' and its effects on young people

[LISTEN] 'Status anxiety' and its effects on young people

Psychologist on individual couple and family therapy Tamara Sosa unpacks the anxieties attached to comparing yourself to others.

Popular articles
I’ve never seen anything like this! – Simon Brown on Old Mutual vs Peter Moyo

I’ve never seen anything like this! – Simon Brown on Old Mutual vs Peter Moyo

The Money Show’s Bruce Whitfield interviews Simon Brown, Financial Educator at Just One Lap.

[WATCH] Volkswagen’s new feel-good Kombi ad 'Cupcake Boss' is brilliant

[WATCH] Volkswagen’s new feel-good Kombi ad 'Cupcake Boss' is brilliant

Advertisers traditionally warn against working with children. In this ad it works beautifully, says ad expert Andy Rice.

Court orders Gupta-linked Trillian to pay back R600 million to Eskom

Court orders Gupta-linked Trillian to pay back R600 million to Eskom

It also ordered the company to pay for all the costs of the application. Bruce Whitfield interviews EWN’s Clement Manyathela.

Learn to invest, then watch your money grow

Learn to invest, then watch your money grow

Ray White interviews Thobelani Maphumulo, author of "Invest Your Way to Wealth".

Lawyers want to know what exactly the Zondo commission will ask Zuma

Lawyers want to know what exactly the Zondo commission will ask Zuma

Tiso Blackstar specialist reporter Karyn Maughan says the former president has maintained that there is no evidence against him.

Even if Zindzi was not an ambassador you would still be touched, says Eusebius

Even if Zindzi was not an ambassador you would still be touched, says Eusebius

Eusebius McKaiser reflects on the tweets by Zindzi Mandela on the land issue, sparking a debate.

SA’s richest woman opens up about being a refugee and becoming a billionaire

SA’s richest woman opens up about being a refugee and becoming a billionaire

Magda Wierzycka – Sygnia’s renegade CEO – on her attitude toward money (hopes and fears, successes and failures, etc.).