This time of year is a rough one is the Southeast. It’s a time of angiosperm related hyprocrisy. It’s so pretty outside that it cries out for Easter egg hunts, picnics, and other outside activities.
(it really does look like this)
Unfortunately, once the weather is warm for a few days, it looks like this.
(Sci’s car this morning, only it was worse than that. RUN FOR YOUR LIVES.)
As you might be able to imagine, this sort of thing means that the sneezing rate in the south has a remarkable uptick in the spring (though there’s no data on this, and compared to fall and summer allergies and winter colds, Sci might indeed just be spouting off lies right now).
But did you know that there are some people who will sneeze on a bright, sunny day, regardless of the pollen count? Did you know WHY?!
Langer et al. “When the Sun Prickles Your Nose: An EEG Study Identifying Neural Bases of Photic Sneezing” PLoS ONE, 2010.
And the best part of this study, what do you CALL the “photic sneeze reflex”?
ACHOO (Autosomal Cholinergic Helio-Ophtalmologic Outburst) syndrome. Some grad students who came up with this were probably giggling hysterically over their beers for this one.
(Sci would like to note that she sneezed no less than about 5 times during this write-up, though probably not due to sunlight)
According to the authors of this study, exposure to bright light, like sunlight, causes spontaneous sneezing in 24% of individuals! That’s a lot. Sci’s not really sure if this is a good sampling, though her’s isn’t much better, as she just asked around the lab about found a ratio closer to 1/6. But anyway.
The authors of this study wanted to determine what brain areas might be responsible for this effect. Sneezing is a reflex consisting of a big inhalation and a forced exhalation, and the locus for it in the brain may be along the spinal trigeminal nucleus, though that’s only been found in cats, not humans (also, it occurs to Sci that she really SHOULD write a post on the cranial nerves, because they are SO AWESOME. Someday). The reflex is triggered (we think) by somatosensory input coming from the nose saying that something is up in there.
So why on earth would your NOSE tickle when you’re exposed to sunlight?
To start to find this out, the authors of this study took a bunch of people with ACHOO syndrome (hehehehehe), and a bunch of controls. They put them in a chamber, and hooked them up to an electroencephalogram (EEG) to look at brain activity. Then they showed them a checkered box, followed rapidly by a burst of light, and checked out the brain activity. They used the EEG and a questionnaire to measure brain activity, and how much your nose tickled when you were exposed to bright sunlight.
This makes for some cool images.
What you can see up in the top section of the figure is the neural activation of the subjects around the light stimulus. You can see that there are several places where the sneezers’ brain activity was increased. And in the bottom of the figure you can see where. The sneezers show higher brain activity (in red) in the occipital lobe, which is an area of the brain which processes visual information.
They also looked at the prickle that the subjects felt in their noses when they were exposed to bright light. And that effect was even stronger.
You can see the red line above showing the photo sneezers had much higher nose-tickle response to bright light, and showed stronger activity in the somatosensory cortex, an area that processes sensory information. So it appears that people with ACHOO Syndrome have higher sensory responses to both the tickle sensation and to the visual stimulus of the bright light.
Unfortunately, they weren’t able to come up with a connection between the two areas and a sneeze reflex center (we’re not that good yet), but it’s certainly a first step, and the hypothesis is that the insula, may link the areas, though other pathways could exist as well (the insula is totally everyone’s favorite brain area right now, ain’t it?).
Now you might think: but how did they separate it out from the actual SNEEZE?! Sci wonders that, too, though it appears the neural stuff they got was fast enough that it wasn’t a problem, where was the SNEEZE?! What were the areas lighting up then? I’m sure there are a lot of them, but it’d still be a cool picture to see.
*ACHOO*
*sniff*
Langer N, Beeli G, & Jäncke L (2010). When the sun prickles your nose: an EEG study identifying neural bases of photic sneezing. PloS one, 5 (2) PMID: 20169159
Filed under: Friday Weird Science, Neuroscience | Tagged: insula, occipital cortex, sneezes, somatosensory |
Are you Scicurious? 
I actually have this condition. Not only does it happen to me when coming from dark-ish to bright conditions, but any significant change upwards, beyond a certain point anyway, will trigger it. Like if I’m reading a book outside the glare from the pages will strike me just so and set off a sneeze or two.
Thinking about bright light makes my nose tickle a bit too.
I only heard about the photic sneeze thing last year, and it was kind of nice to know it’s a real thing and I’m not just crazy. Every time I mentioned “sunlight makes me sneeze” to anyone I just got this look.
Putting someone in the scanner and getting them to sneeze could be problematic. What to do about the motion artifacts? Strap their heads down?
Glad you liked it! I was the Academic Editor for this paper and took it on in part because my brother had the ACHOO thing and because I thought it was a very original and creative idea.
This has affected me my whole life.
I have always noticed it more when I was walking from dark to light on very warm, sunny days, such as when exiting a movie theater or artificially lit store. Almost always, an asphalted parking lot is involved. As a child I assumed that those squiggly lines you see in the air coming off of a heated surface tickled the nostrils. I know that can’t be it, but it remains a mystery even to those who study it professionally, so…
Anyway, curious about this since childhood, I must say it is disheartening to click on a headline like yours, only to find out that… no one frickin’ knows, yet. Oh well. It still happens, but not like it did, as a child, when I was guaranteed a sunny sneeze after a movie.
Question: do other photic sneezers enjoy, dislike, or feel indifferent to the condition? I really like having it, but I’m curious about what others think.
As a person with ACHOO syndrome (and who also finds the moniker quite hilarious), I’d always guessed it could be there as an evolutionary advantage, protecting me from staring at the sun or other bright light sources by quickly causing me to look down as a result of the sneeze and therefore helping to protect my eyesight.
In response to Marilyn, I’m largely indifferent to the condition but admit that there are times when I quite like it, as I can trigger a sneeze intentionally, which perhaps bizarrely, I find I need to do now and then.
Marilyn,
I too like it, and it makes people laugh – especially my daughter when I sneezed 46 times in a row, laughing uncontrollably between each, as we counted 🙂
Jason,
EEG does not require that you are in a scanner. It involves placing superficial electrodes on the subject’s scalp.
I’d be curious to see what would happen if you did a follow-up on your informal “photic-sneezers” survey. When someone first told me that this happened to them, I thought they were crazy, but after hearing about it, I noticed that I do it too. I would imagine that there’s a large group of people that sneeze either infrequently, or only in response to strong stimuli, and who don’t really realize that this happens.
Wow, I always thought this was more common. I’ll just add this to the list of things that make me weird…
I only really get it from sunlight though. Indoor light rarely has any effect.
Wow, I always thought this was more common. I’ll just add this to the list of things that make me weird…
I only really get it from sunlight though. Indoor light rarely has any effect.
Cool, I’m glad I’m not alone…although I don’t really mind them. I always though it had something to do with my pupils adjusting to the much brighter light, as if, perhaps when those nerves fire off, they accidently tell my brain to sneeze as well, seeing how it’s happening in the same general nasal/eye socket region.
I totally have ACHOO syndrome! I thought everyone did this, but it so much cooler now that I know I’m special and also some of the science behind it.
This is true, but you’re left with poor spatial resolution.
I have the ACHOO syndrome too! Actually sometimes when I need to sneeze and have a hard time getting the sneeze out I’ll look at sun light and I’ll be able to sneeze. I’ve gave people this advice and they look at me crazy. I try to explain to them that this technique has always worked for me but they still won’t believe me. See I’m not crazy, there’s actually an explanation!
FINALLY! An explanation for my weird sneezing issues.
It IS sort of handy, though… when you have to sneeze, but it’s just not coming, you can stick your head under the lampshade and VOILA! Of should I say ACHOO?!
How about random sneezing? My grandfather did this, suddenly it would take 10 to 20 sneezes to get it out of his system. I started doing this too in my 20’s. It’s like the thermostat goes out of whack, and sneezing is the reset button. It can happen anytime, even in very hot weather, suddenly there are goosebumps, extended sneezing, then it’s back to normal, like nothing happened. My son, now in his 20’s is starting to do this too, which is great revenge, as he used to laugh at my sneezing attacks. All that sneezing is really a nice high – but why?
I too thought is was a fairly universal response. If there is an adaptive purpose to it, perhaps its as an indicator of pupil dilation so we are aware of visual impairment lest we walk into the jaws of a predator during dramatic lighting changes. Interesting to speculate.
And next weeks subject matter: why running water makes us urinate…
I too thought is was a fairly universal response. If there is an adaptive purpose to it, perhaps its as an indicator of pupil dilation so we are aware of visual impairment lest we walk into the jaws of a predator during dramatic lighting changes. Interesting to speculate.
And next weeks subject matter: why running water makes us urinate…
The cause is a congenital malfunction in nerve signals in the trigeminal nerve nuclei. The fifth cranial nerve, called the trigeminal nerve, is responsible for sneezes. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex.
This sneeze reflex can also be brought on by sudden inhalation of cold air or exposure to strong flavors. This implies an overstimulation of any nerve close to the trigeminal nerve can cause the sneeze reflex.
The cause is a congenital malfunction in nerve signals in the trigeminal nerve nuclei. The fifth cranial nerve, called the trigeminal nerve, is responsible for sneezes. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex.
This sneeze reflex can also be brought on by sudden inhalation of cold air or exposure to strong flavors. This implies an overstimulation of any nerve close to the trigeminal nerve can cause the sneeze reflex.
Not a ‘malfunction’ nor a ‘disease’, rather an ancestral beneficial mutation (selected for Oxygen conservation during dive-foraging for seafoods, in parallel to other animals which derive nutrients from shallow seas), which occurred during the split between (wading, swimming, diving, backfloating) human and (wading) chimps, the gene uniquely occurs on the human chromosome which fused giving humans 46 chromosomes, compared to ape 48 chromosomes, it is asociated with hypothyroidism (Iodine conservation) and hemochromotosis (Iron conservation) genes. The gradual development of boats and nets/baskets vestigialized the photic sneeze reflex, it remains in low melanin descendant populations (European, Chinese). ‘Sudden cold air’ usually induces gasping, not sneezing, and ‘strong flavors’ include specifically peppermint (which is a natural herb hybrid only found at waterside which actively repels mosquitos, similar to other strongly scented waterside herbs like lemongrass) and a few other materials with similar chemistry (cacoa). Post-dark adaptation solar powered instantaneous exhaling allowed efficient foraging at depth, parallel to other fauna. “Overstimulation” is not necessary, merely engaging the pupillary light reflex post-dark adaptation. More or less, IMO.
I learned about this awhile ago, and mentioned it to my parents, wondering which of them I got it from. My dad looked at me like I had two heads, and my mother looked at me and said “honey, everybody does that.” Laughed my ass off.
No one in my boyfriend’s family does it, and they find it hilarious. Everyone always turns to look at me when we first step outside on a sunny day…and of course, I perform, right on cue! I get teased a lot for it, and it really bothers me occasionally when I’m driving, but other than that I don’t mind too much.
This is really interesting. I know when I was young and would have that tickle in my nose my mom would always tell me to look at something bright and it would always help me sneeze. It never failed! The human body and reactions to things really is fascinating. Thanks for the awesome post!
This is really interesting. I know when I was young and would have that tickle in my nose my mom would always tell me to look at something bright and it would always help me sneeze. It never failed! The human body and reactions to things really is fascinating. Thanks for the awesome post!