Hiccups, yawns and sneezing

Written by: 
Simon Crompton, medical writer & author

Hiccuping, yawning and sneezing afflict us all, but they are also among our most mysterious ailments - underresearched and poorly understood because they are rarely life-threatening. But the handful of people who suffer extreme versions of these minor annoyances are more than freaks of nature. Through them, doctors and scientists are realising that the seemingly useless functions of hiccupping, yawning and unprovoked sneezing may actually reveal a lot about the workings of our brain and our evolutionary past.


There are 101 hiccup cures, none of which is sure-fire - mainly because hiccups are still so poorly understood. Occasionally, chronicA disease of long duration generally involving slow changes. hiccups can be a sign of disease - for example neck tumours, or laryngitis. But normally we associate them with eating or drinking too much, lack of sleep, excitement or stressRelating to injury or concern.. Often the source is unknown. A farmer from Iowa hiccupped continually for more than 60 years and never found out why.

Like sneezing, hiccupping is a reflex. A stimulus - and in many cases it’s almost certainly discomfort in the stomach and the food tube that leads to it - makes chest nerves send signals to the rib muscles and diaphragm to contract, making us inhale rapidly. But the reason why we need them has long baffled scientists. They are likely to be a remnant from our evolutionary past. Scientists from Piti-Salpêtrière Hospital in Paris have observed that many amphibians and primitive fish - such as tadpoles and lungfish - which breath air but still have gills, have to hiccup to push water over their gills without inhaling it into their lungs. The mechanism may have persisted 370 million years since such creatures hauled themselves out of the swamps because they served some purpose in the creatures into which they evolved. In mammals, the reflex may help babies to suckle properly.


We all yawn when we’re tired or bored - but why do we also yawn when other people do, or when we’re stressed? The conventional view is that when our body gets short of oxygen, for example because we’re so tired that we’re breathing slowly, the yawn reflex is triggered to make us draw in more air. The only problem with this theory is that studies by Dr Robert Provine, a neuroscientist at the University of Maryland, have shown that low bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. oxygen doesn’t actually prompt yawning. Dr Provine thinks it’s far more likely that yawning, like stretching, is a way of flexing muscles and increasing heart rate, making us ready for action.

But why do we yawn if other people do? Many animal species yawn, but only humans, chimpanzees and macaque monkeys suffer from contagiousAny disease that is communicable. yawning. The latest studies suggest that it’s to do with our sense of empathy. Researchers from Birkbeck College have discovered that children with autism - a developmental disorder affecting people’s ability to make emotional ties with others - do not yawn at the sight or thought of other people yawning. Yawning may have developed among higher animals, scientists theorise, as a social signal that indicated tiredness or stressRelating to injury or concern., so that sleeping and watchfulness could be co-ordinated. In the highest primates it became so strongly ingrained into our watchfulness for others that it became a symptom of our empathy.

This still doesn’t explain one of the strangest yawning phenomena of all - that many people report a really good yawn being like a “mini-orgasm”. Yawning causing orgasm has occurred in people suffering from heroin withdrawal and those on some antidepressant drugs. One married woman in her late twenties who was on the drug clomipramine for depression has her story told in The Canadian Journal of Psychiatry. She asked her doctors how long she might be allowed to take her tablets. When asked why, she sheepishly admitted that she hoped to take them for a good while yet. Ever since she had started taking them, she could bring on orgasm by deliberately yawning.


The purpose of sneezing if you have a cold, or encounter pollen or dust, seems obvious: expelling invading particles. But some people sneeze for other reasons. About a quarter of us sneeze when we look at a bright light: the photic sneeze reflex. There have been medical reports of people sneezing when their stomach is full. 

Sneezing is normally triggered by the membranes in the nose being stimulated. This sends a signal to the brain, which then tells the nose, mouth and chest to convulse into a sneeze. But we have other reflexes, such as the pupil of the eye constricting in the glare of sunlight. What seems to happen in sun-sneezers is that the sneeze reflex and the pupil constriction reflex, which should take different routes in the brain, cross over and become confused. There is likely to be a geneticRelating to the genes, the basic units of genetic material. source to this, because sun sneezing runs in families. 

Some researchers think that all types of sneezing are a throwback to our evolutionary past rather than useful now. Dr Tom Wilson, a pathologist from Washington University School of Medicine, points out that sneezing is likely to force out germs only if you do it through your nose - but humans usually expel air though their mouths when they sneeze. Animals - dogs, for example - sneeze only through their noses, making it far more useful.

What cures work?


Cures such as giving someone a shock or drinking a glass of water from the wrong side sometimes work. If they are successful it is usually because we are depriving the body of oxygen, which means that the body has to “reboot” breathing and reassert control to prevent damage.


Try breathing through the nose because a study shows that this can cool your brain and those with a cooler brain tend to yawn less.


Putting your finger under your nose, or even pinching your nose, can temporarily delay a sneeze by confusing the nerveBundle of fibres that carries information in the form of electrical impulses. impulses travelling from your nose to your brain. But it will come out in the end.

(c) Simon Crompton   www.simoncrompton.com