For every person who embraces his or her gray hair, many more curse this very visible sign of aging.
Now a new study confirms what many have suspected and offers a bit of hope: stress can lead to gray hair and taking stress away appears to reverse the process, allowing white strands to return to the natural color at the root.
But don’t put away the hair dye just yet. The effect is temporary, possible for only a certain age window and affects just a few hair follicles on someone’s head. So if you’ve had gray hair for many years, a long relaxing vacation won’t help it start growing blond, auburn or brunette again.
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Still, the findings show aging is not a linear, fixed, irreversible process, but is malleable so it can be “bent” and perhaps reversed a little bit, said Martin Picard, the study co-author and an associate professor of behavioral medicine in psychiatry and neurology at Columbia University in New York.
He was amazed at the number of people who reached out to him to share stories of their white hair growing out in color.
“People were saying, ‘I saw this when I was younger. My gray hair went back to dark after this event had happened and people said I was crazy because it's not possible. Thank you for confirming that I'm not crazy,’” Picard told TODAY.
“It tells me that what we found in our small cohort and what we documented quantitatively for the first time in this study is probably much more prevalent than we think.”
For the study, published in eLife, researchers plucked, imaged and analyzed 397 hairs from 14 healthy people ranging in age from 9 to 65. None used hair dye, bleaching or other chemical treatments and all self-identified as having some gray hairs or two-colored hairs.
“Reversal of graying” — instances of hairs that had a white top segment, but were growing in darker at the bottom, or “repigmenting” — was discovered among 10 of the participants.
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They were asked to look back and identify periods of extreme stress during the last year. The researchers then looked at tiny slices of their hair — a “bioarchive” that Picard compared to the rings of a tree in the ability to hold information about the past — to align what happened to the pigment during those troubled times. It turned out the increase in stress corresponded with hair graying — associations the paper described as “striking.”
But when the participants reported a reduction in stress, like going on vacation or resolving the tense event, the hair regained its pigment. (Once the hair grows out of the scalp, it doesn't change color. It's just the new growth at the root that can.)
Why would stress lead to gray hair?
The stress response evolved to help humans survive danger. If you’re confronted with a tiger, the body goes into fight-or-flight mode: The heart beats faster, hands get cold, the skin may flush and limbs may tremble.
Today, a nasty email, a controlling boss or an unhappy marriage can elicit the same reaction.
“The stress response is necessary because it will promote survival in evolutionary terms. But there's a cost to being stressed and the cost is that maybe some of the cells age faster,” Picard said.
“The (gray) hair is just an external reflection of this internal cost of stress… you get to see the effect of stress with the naked eye through the change in color in the hair.”
Hair growth demands lots of energy and while strands are growing, cells receive signals from the body, including stress hormones, the authors write. It’s possible these exposures trigger changes in hair pigmentation.
Graying reversal won’t work for everyone
Hair needs to reach a threshold before it turns gray, Picard said. If strands are about to go gray anyway — perhaps near middle age — a stressful event might push hair cells past that threshold earlier, the study noted. Then when the stress ends and the hair is just above the threshold, it could revert back to dark.
Some people start seeing gray hairs in their 20s; others in their 50s, so that window of opportunity will vary.
“But the hairs that have been gray for 30 years are probably unlikely to be reversible,” Picard noted.
Any graying reversal is likely temporary: As a person gets older, the hair is going to pass the threshold again as part of the aging process and go gray — this time, for good.
How to keep your cells young:
Beyond finding ways to lower stress, certain habits can positively influence human aging biology:
Don’t eat too much: “Overeating and giving your body too much of anything is not good, and there's a lot of good animal studies showing that if you feed animals fewer calories, it positively affects their aging biology,” Picard said.
Exercise: “Being physically active has a positive universal effect on the whole body. It stimulates different parts of the body to talk to each other and stimulates good hormones being released,” he noted.
Do things that make you feel grateful or loved: Experiencing positive emotions is associated with better function of mitochondria, the little battery-like organelles in cells. “Maybe that's why when we feel good, we feel like we have more energy,” Picard noted.
