Cooper has proudly rocked his salt-and-pepper locks since he was about 20. But let’s face it, that look’s not for everyone. Since the beginning of time, men and women alike have sought to avoid going gray. And for hundreds of years, people have pointed to stress as the cause of gray hairs. But that’s always been thought as an urban legend, with no proof to back it up—until now.
“Everyone has an anecdote to share about how stress affects their body, particularly in their skin and hair—the only tissues we can see from the outside,” Ya-Chieh Hsu, the Alvin and Esta Star Associate Professor of Stem Cell and Regenerative Biology at Harvard, said in a release. “We wanted to understand if this connection is true, and if so, how stress leads to changes in diverse tissues.”
Stress affects everything from your workouts to your sex life and how you sleep—so the scientists had to figure out exactly how it grays our hair. To do so, they systematically eliminated different body systems that could connect stress to hair color. They eventually landed on the sympathetic nerve system, aka the body’s flight-or-fight response. Sympathetic nerves, the researchers wrote, branch out into each hair follicle.
Stress causes those nerves to release norephinephrine, a chemical that gets taken up by pigment-regenerating stem cells that color our hair.
When we’re stressed, our pigment-coloring cells get activated excessively, thus depleting our supply. In English, the more stressed we are, the less cells we have to color our hair. And once they’re gone, they’re gone.
“Acute stress, particularly the fight-or-flight response, has been traditionally viewed to be beneficial for an animal’s survival. But in this case, acute stress causes permanent depletion of stem cells,” Bing Zhang, the lead author of the study, said in a release.
So if you’re not a fan of looking like a silver fox, chill out. Your hair will thank you.