Here’s Why You Scratch Yourself When You’re Stressed

Updated: Sep. 25, 2017

It's totally normal — and it could save you from violence.

scratchDJTaylor/ShutterstockThere are plenty of ways to cope with being stressed. Rubbing your palms, for example, does wonders—so does calling your mom. Many of us though, consciously or unconsciously, prefer to scratch ourselves.

There are a couple of theories why we (and other primates) do this, the foremost being distraction. The reason scratching a mosquito bite feels so good, some say, is because the relative pain of your nails raking against your skin is a welcome distraction from the greater annoyance of the itch. Scratching against stress could serve a similar function. (That said, you should never scratch a mosquito bite if you can help it.)

And while flailing your fingernails against your epidermis may seem like an unrefined use of your human body, a group of monkeys has shown scientists that stress-scratching might actually come with some sophisticated survival benefits. Researchers from the University of Plymouth spent eight months in Puerto Rico studying a wild troop of rhesus macaques—smallish primates that grow to be about 12-17 pounds on average. Watching specifically for when the macaques scratched themselves, the team found a few interesting social patterns.

For one, macaques were more likely to scratch during periods of increased social stress, such as hanging out with a high-ranking individual or one they didn’t know well. (Perhaps you can relate.) Secondly, when those stressed-out primates did scratch in the company of others, the following interactions were about 25 percent less likely to be aggressive, and more likely to be friendly. The reason behind this? The researchers think it could be that even macaques are able to recognize stress when they see it—and they don’t want any part in it.

“Potential attackers may avoid attacking stressed individuals as stressed individuals could behave unpredictably or be weakened by their state of stress (rendering aggression risky and/or unnecessary),” the researchers posit in their paper on the topic. “Observable stress behavior could therefore have additional adaptive value by reducing the potential for escalated aggression, benefiting both senders and receivers by facilitating social cohesion.”

To put that in terms a monkey could understand: maybe the reason you scratch yourself when you’re stressed is to tell the world that you’re stressed. And perhaps that makes the world a little nicer toward you in return.