We already knew that stress could be responsible for hair turning gray; now a recent study suggests that it may not always be irreversible.

It's good news for those of us who suffered unprecedented levels of stress during the pandemic and who may be seeing the effects on their locks. In fact, once the period of stress is over, hair color may be restored.

You should no longer stress out about going gray! Researchers from Columbia University Vagelos College of Physicians and Surgeons in New York have confirmed in a study that stress does indeed cause hair to turn gray, supporting previous research on the subject with quantitative evidence, but they also reveal that it is completely reversible.

A characteristic of aging, hair going gray is also linked to psychological stress, and in such cases, it may be possible to regain its original color once the stress is eliminated.  

"Understanding the mechanisms that allow ‘old' gray hairs to return to their ‘young' pigmented states could yield new clues about the malleability of human aging in general and how it is influenced by stress," explains Dr Martin Picard, associate professor of behavioral medicine (in psychiatry and neurology and senior author of the study.

He continues, "Our data add to a growing body of evidence demonstrating that human aging is not a linear, fixed biological process but may, at least in part, be halted or even temporarily reversed."

The key role played by stress

Published in the scientific journal eLife, the study is based on the development of a new method to capture very detailed images of tiny pieces of human hair.

The goal is to quantify the extent of pigment loss responsible for graying in each of these tiny pieces of hair.

The researchers analyzed the hair of 14 volunteers, who were asked to keep a diary recording their phases and stress levels on a weekly basis.

The results of the images of the tiny pieces of hair were then compared to these stress diaries.

The verdict is surprising, but unquestionable.

The researchers discovered that some gray hair could return to its original color.

By associating this finding with stress logs, they also noticed an association between stress and graying, and conversely a link between the return of the natural color of the hair and the lifting of stress.

"There was one individual who went on vacation, and five hairs on that person's head reverted back to dark during the vacation, synchronized in time," noted Dr Martin Picard.

What's the mechanism?

The scientists also measured the levels of thousands of proteins present in the hair and were interested in how these protein levels might change over the length of each hair.

The goal was to find out how stress could influence the graying of hair.

The study suggests that stress-induced changes in mitochondria may provide an explanation.

"We often hear that the mitochondria are the powerhouses of the cell, but that's not the only role they play.

Mitochondria are actually like little antennas inside the cell that respond to a number of different signals, including psychological stress," outlines the main author of the study. 

So could reducing your stress level help reverse the trend, and get your hair back in line? Well, it's not as simple as that, as the researchers themselves explain, and they point out that this only happens in certain cases.

"[W]e don't think that reducing stress in a 70-year-old who's been gray for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the gray threshold," conclude the researchers. Message received!