Learn more about the fascinating way researchers believe about how we can actually "re-pigment" our locks.

If any year in the course of our lifespan would have led to more gray hairs, it would have been 2020. (We don't want to rehash it too much, but in case you need a brief recap, we reported on how the stress of the pandemic was making us look and feel older back in March 2021.)

But we're here with happier news today: A scientific discovery that hints at the fact that we might actually be able to someday restore the natural pigment to gray hairs, zero dye required. After examining 323 proteins that determine whether hair would be gray, white or colored, Columbia University researchers gathered gray hair samples from 14 individuals who rated the stress of their past 12 months. For the study published June 22 in the journal eLife, scientists dove into the protein in these hair samples, the hair color and the individual's stress over the last year. They discovered that some normal-hued hairs had been gray at some point during the year, but actually returned to their regular color once higher stress levels went down.

In the future, the researchers hope to replicate these results and also see if this can happen to people over age 40; so far, they've only witnessed this re-coloring in those under 40.

"I was not surprised by any of the stressors that correspond with graying; I was surprised to see how strong of an impact a vacation had on the reversal of graying," Ayelet Rosenberg, lead author on the study, tells Mashable. "One participant went on just a 2-week trip, and amazingly enough, five of their hairs regained color afterwards."

Woman with some gray hair
Credit: Getty Images / Tom Werner

We know that too much stress can worsen chronic inflammation, lead to weight gain, increase heart disease risk and impact sleep quality, but most of these effects are internal—and fairly invisible. But gray hairs stare right back at us in the mirror as a visible cue that either: A. You're aging, or B. You're far too frazzled.

"Hair is unique, because it is a visible change that also indicates changes happening on a cellular level," Rosenberg says in the Mashable recap about these findings, nodding to the fact that stem cells are at play. "The ideal outcome would be for doctors to one day be able to use hair pigment as a diagnostic tool, using our method. If somebody did have a sudden onset of gray hairs, it would be worth looking at their stress levels that correspond to that point in their life."

This is one of the first scientific clues that stem cells may be powerful enough to "re-pigment" gray hair. In particular, melanocytes, the variety of stem cells that reside within hair follicles.

"The depletion of stem cells would imply that the graying is permanent, but this has only been shown in mice. Some transient stem cells may come in, which could possibly be responsible for the re-pigmentation that we are seeing here," Rosenberg tells Mashable, noting that more research is needed to expand on this discovery.

The scientists hope that this revelation may inspire future stem cell therapies that can nudge our own melanocytes to jump back into action later in life (rather than requiring us to go gray or artificially color our hair as a cover up). For now, our best bet is to take this as a reminder that many of us are overly stressed, and anything we can do to ease up might be beneficial for our overall health and our hairdos.