You may have first noticed it—your first gray hair—in your forties or fifties. Or perhaps you went gray (or grey, depending on how you like to spell it) earlier or later. Graying, which has genetic roots but affects nearly everyone who lives long enough, has been blamed on all sorts of things, including “paroxysms of rage, unexpected and unwelcome news, habitual headaches, overindulgence in sexual appetite, and anxiety,” according to an early 19th-century French dermatologist.
Here we set the record straight, with answers to six questions you may have about hair graying, scientifically known as canities.
What makes hair turn gray?
Graying occurs as specialized cells in hair follicles called melanocytes lose their ability to produce pigment (melanin) over time. It’s not that hair actually turns gray, but that new hair with less melanin grows in, resulting in a range of colors from gray to silver to white. White hair has virtually no melanin but, as an optical illusion, looks gray against a backdrop of darker hairs.
It’s still not fully understood what causes melanocytes to change, however, and many complex mechanisms have been proposed. An interesting one, described in a paper several years ago in the FASEB Journal (the journal of the Federation of American Societies for Experimental Biology), is that hair becomes gray from a buildup of hydrogen peroxide inside the follicle. Hair normally has a little hydrogen peroxide that’s kept in check by the enzyme catalase, which breaks down the chemical into oxygen and water. But with aging this enzyme is reduced, so the hydrogen peroxide accumulates, causing a disruption in normal melanin production.
By the way, it’s a myth that plucking one gray hair will cause two to grow in.
Does everyone go gray the same way?
No. Graying varies by gender and race. According to a 2012 survey of more than 4,000 middle-aged people across the world, published in the British Journal of Dermatology, 74 percent of those ages 45 to 65 had gray hair, with men more affected than women. People of Asian and African descent had less gray hair at any given age than Caucasians.
Patterns of graying also differ. For example, a 2011 paper in Acta Dermato-Venerealogica that focused on Koreans found that gray hair tends to appear first at the temples in men and in the frontal area in women, while premature graying tends to occur on the side and back, compared to later graying, which tends to affect the front more. And as you may have noticed, beard hair often goes gray sooner than head hair, while underarm, pubic, and chest hair sometimes stays dark until old age.
Does stress play a role in graying—and can it really cause hair to go white suddenly?
While graying has a genetic basis, it’s possible that stress can hasten its arrival. One hypothesis is that stress hormones lead to inflammation and free-radical production, and this in turn affects melanin production or the bleaching of melanin. As for “going white overnight,” there are many anecdotal (and historical) reports—but no hard proof. Both Thomas More and Marie Antoinette, for example, are said to have turned white the night before they were beheaded. Perhaps a more plausible explanation for this is that stress brings on hair loss (alopecia areata) that specifically targets pigmented hairs, leaving behind only the white hairs already present. But that would mean that such a sudden change in hair color would be accompanied by significant hair loss, which has not always been the reported case. On the flip side, there have been cases of spontaneous repigmentation of hair, for reasons that are not always clear.
Does smoking cause hair to go gray earlier?
Smoking has consistently been linked to premature graying. In a study in the Indian Dermatology Online Journal of more than 200 people, smokers were 2.5 times more likely to experience premature graying (before age 30) than nonsmokers. Another study, in the Journal of the American Academy of Dermatology, linked smoking to premature graying in young men. The mechanism, similar to one proposed for stress, is that free radicals (produced by smoking) may damage the cells that produce melanin.
Can gray hair be brought on by illness?
Possibly. Certain autoimmune disorders, as well as other conditions such as HIV infection, Hodgkin’s lymphoma, chronic protein deficiency, severe iron or copper deficiencies, and obesity may increase the risk of premature graying. In addition, some observational studies have linked premature gray hair to increased risk for certain disorders such as cardiovascular disease and osteoporosis, but aside from having mixed results, they only show correlations and do not prove cause and effect.
Embracing your gray
In lab research, white hair follicle cells have been stimulated to produce pigment again, and some scientists are hopeful that eventually a “cure” for graying will be possible. In the meantime, one option is to camouflage your gray, as does Hillary Clinton, who said on the campaign trail, “You won’t see my hair turn white in the White House . . . I’ve been coloring it for years.” Better yet, learn to love your gray: Going au naturel not only frees you from exposure to potentially harmful dye chemicals, it will also make you fashionable, since “granny hair” has been one of the hottest trends of the year, sported by both young celebrities (like Lady Gaga) and older ones (like Jamie Lee Curtis and Dame Judi Dench). If you don’t believe us, check out this Instagram feed or just search online for “granny hair” to see some chic examples.