Can Stress Turn Your Hair Gray?What the Studies Found

“Worry will turn you gray” is old advice. Two recent studies put it to the test, and a large survey checked another piece of folk wisdom along the way.

First, the “50 by 50” rule

The rule says that at 50, half of people are at least half gray. A survey of 4,192 volunteers worldwide, rated against color swatches, found otherwise:¹

• Between 45 and 65, 74% had some gray, covering 27% of their hair on average.¹
• The share who were at least half gray at 50 was 6% to 23%, depending on ancestry and natural hair color.¹
• Women had less gray than men, and people of Asian and African descent had less than white people of the same age.¹

The lead author worked for L’Oréal.¹

The mouse study, 2020

Harvard researchers stressed mice, and the mice went gray.² The cause wasn’t stress hormones from the adrenal glands or an immune attack.² It was the fight-or-flight nerves around each hair follicle: they released a burst of noradrenaline that drove the pigment stem cells to multiply, move out and run out for good.² Blocking that burst prevented the graying.²

It’s a mouse study. Several authors filed a provisional patent on methods for controlling graying.²

The human hair study, 2021

Columbia researchers read single hairs like tree rings, scanning the color along 397 hairs from 14 people.³

• Some gray hairs regained their color on their own, in women and men, across ages and ethnicities.³
• In one person, every hair that regained color did so as stress fell, during the lowest-stress month of the year, after a two-week vacation.³
• A computer model suggested that hairs near the graying threshold might tip back and forth.³

The limits: 14 people with an average age of 35, who were asked to bring in their two-colored hairs, and stress was rated looking back.³ The authors’ own summary says there’s no definitive research on stress and graying in humans.³ The returning color was temporary and seen in hairs close to the threshold, so it says nothing about hair that has been gray for years.³

What this means

Stress may speed graying in hairs already on their way, but the human evidence is early. Gray hair is a choice about looks, not a health warning on its own. For the basics, see why your hair is turning gray. Stress can also trigger shedding about three months later: see why your hair is shedding so much.

Try: “I went noticeably grayer in the year my mother was sick. Is there anything in my bloodwork worth checking, or is this just timing?”

Hair, Everywhere covers this in Chapter 10, “Less Here, More There,” in a section called “Gray Hair, Briefly.” Its Hair Log keeps dated photos and notes about what was going on in your life, so you have a written record instead of relying on memory. See the book.