Subtitles section Play video Print subtitles Hey there Head Squeezers, I hope you're well. So you sent in a whole load of eye related questions to me before. I've looked at eye bags, eyebrows and here's another eye popping question for you now. It was sent in my hugessfan on YouTube who asks Why do we close our eyes when we sneeze? Now first of all lets debunk an old school myth. If you sneeze with your eyes open your eyes do not pop out on springs like you see in the cartoons. That will not happen! Alight? OK? Ok, goo. Now sneezing is involuntary. When you are struck down by the common cold or man flu as we like to call it your nasal cavity is more swollen and more sensitive and any irritation will cause you to sneeze. Something like pollen, or dust, or even fur from your mate's cat, if it gets up your nose. To get technical, an irritant when it contacts the nasal mucosa it triggers the trigeminal nerve, which sends a signal to your brain which goes to the lower part of your brain known as the medulla. And then you know what happens the chest expands, your lungs fill with air, and achoo, you sneeze snot everywhere. And James did a really good film on where snot comes from, I'll put a link to that at the end of this one. But get this, you sneeze out over 5000 droplets of mucus and air at speeds up to 100 miles an hour. But of course you will all that high octane action because your eye lids actually pull down your curtains. But why do you sneeze? It's one of science's big mysteries. We think it's an involuntary response just like if you get tapped just under your knee cap your leg goes flying up. So what could be causing it? Well you could be shutting your eyelids because as you sneeze out the germs and bacteria they don't fall on your eyes. Or maybe your eyelids shut down because they're one of a series of muscles that tighten because of that involuntary response. Some people's eyes do actually stay open, if you're one of those people then please do let me know in the comments below this video, or indeed, if you know of anyone. That's all the time I've got right now. Please do keep sending me in your questions on twitter, on facebook, or in the comments below. Until next time happy head sneezing, head squeezing.