"Sorry, am I boring you?"
Have you ever wondered why yawns are infectious? Sometimes all it takes is seeing someone yawn, hearing them talk about it or even reading about it. Suddenly, you've got the uncontrollable urge to yawn yourself.
Don't start yawning yet - this is actually really interesting.
And it's not the only bodily function that's got us intrigued. From embarrassingly loud stomach rumbles to farts and even blinking, here BBC Bitesize takes a look at why our bodies do the things they do.
Why do we yawn?
One theory you may already have heard is that yawning helps you breathe. It allows more oxygen to enter your body, expelling excess carbon dioxide in the process.
However, several experiments in the 1980s proved this isn't true. So, why do we yawn? More recent research suggests it cools the brain down and prevents it from overheating - much like the fan in your laptop.
This could also explain why we yawn when we feel tired, as we're more likely to feel drowsy in warmer temperatures. The jury's still out on this, though, as tests haven't proved it.
As for why we yawn when others do, it's thought that this could be a very old form of communication. The theory goes that a person's yawn would signal fatigue to everyone around them, allowing the group's body clocks to sync up.
Why do our tummies rumble?
Funnily enough, it's not actually your stomach that growls when you're hungry.
When you digest food, your intestines contract to move it through them in a process called peristalsis. When there's air trapped in the intestines, the contraction causes that air to make the rumbling sound - or borborygmus, to give it its scientific name.
Scientists debate whether this rumbling is linked to hunger. It's thought that hormone-like substances are released when we're hungry, which activate signals that encourage you to eat. This sends signals to your stomach and intestines, and voilà, borborygmus!
Why do we fart?
You might want to hold your nose for this one…
We fart on average between five and 15 times every day, but this sometimes embarrassing occurrence ultimately has a useful purpose.
When you eat and drink, you're also taking in some air. Along with the oxygen and nitrogen you swallow, more gases form when the food is digested, like hydrogen, methane and hydrogen sulphide.
Your body naturally absorbs some of these, but the rest needs to go somewhere - and that's where farts come in. The smelliest of these gases is sulphur. Foods such as red meat and some dairy products can contribute to the production of these sulphur-containing gases… And if you've noticed yours smell worse than usual, or you're farting more than you otherwise would, you might be poorly - so make sure to see a doctor.
Why do we blink?
It's widely agreed that we blink because we need to keep our eyes moist. When they're open, the tears that usually cover the surface start to evaporate - and if our eyes are dry, it can be painful. Blinking tops up the fluid, and can also keep out other irritants like dust and bright light.
However, because we blink on average every three or four seconds, some scientists think there could be another reason. So, why else might we do it?
Studies carried out at Osaka University in Japan found that blinking might help us mentally refresh, by giving us a micro-break every so often. It's almost like our bodies are giving us a lot of very short naps throughout the day - which is very considerate!
Why do we sneeze?
On average, we sneeze about four times a day - but as all hay fever sufferers will know, there are days when it feels like it's non-stop.
So, what are we actually doing when we sneeze? It's essentially to get rid of anything that shouldn't be in your nose.
The inside of your nostrils contains sensors that raise the alarm when anything nasty gets inside. This triggers hairs called cilia to move in order to brush it away. If you have a sneezing fit with multiple in a row, it's probably because your nose is making sure it's definitely cleared everything out.
Cilia need mucus to work, so our body produces about a litre of it every day - most of which we swallow. Ew.
This article was published in June 2019 and updated in July 2026.
