In addition to making sure our internal organs don't leak out, skin does amazing stuff for us -- it's covered in white blood cells that attack any invading harmful bacteria. It also sends signals sent from your skin to tell your body's immune system to launch into action.
And it's these signals that are responsible for us dragging our nails across our skin in an effort to rub out an irritant. Itching is usually triggered by an insect bite, a skin disease, viral or bacterial infections, or even as a byproduct of serious conditions, like River Blindness and some types of cancer.
It becomes a serious issue when you begin to scratch yourself into oblivion, freaking out everyone else around you. And according to the article "Ignominious Itch," there have even been rare instances in which the sufferers of acute cases commit suicide.
The problem really takes root when your immune system is out of whack and becomes hyper-vigilant. This is where stress and itching come in -- sometimes begetting the tail-wagging-the-dog scenario: The higher our stress response, the more our immune systems engage, causing inflammation in the body. And the more we scratch to remove the phantom itch.
In 1982 an epidemic of itching and rashes occurred in more than 30 percent of kids in an elementary school in West Virginia. The rashes were caused by itching, and the itching was caused by scratching, which was a result of the anxiety the children purportedly experienced from upcoming statewide exams.
Investigators termed it "epidemic hysteria," and according to Leslie P. Bass it's "very similar to a stampede in the animal world." This isn't surprising when you consider that these kids were sharing a culture-bound stress reaction.
Moreover, itching can be visually contagious. It's similar to seeing someone yawn and then exciting the mirror neurons in your brain, which mirror the action it's witnessing by causing you to actually yawn.
A study published in the Journal of Dermatology demonstrated that the mere suggestion of an itch can easily trigger a response from our central nervous system.
So think of that the next time you have the urge to scratch that itch while among your fellow humans.
Julie Douglas is a podcaster, writer and editor at HowStuffWorks and a sometimes phlebotomist and pyrotechnician, not to mention a fabulist of bios and the co-host of the Stuff to Blow Your Mind podcast.