Why Does Hair Turn Gray?


Sep. 25 2020, Updated 11:09 a.m. ET

Four women smiling with grey hair.
Source: iStock

Maybe while you were growing up your mother threatened that your behavior was causing her to go gray; or your father blamed his time-consuming work for the reason why his hair turned gray. Or maybe you know someone young, someone who endures a lot of stress whether because of a high-risk job or other reasons, and their hair is turning gray, too. 

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Regardless of what you think you might know about how and why our hair turns gray, there’s a bit of myth-busting that needs to happen in order to normalize a perfectly normal symptom of aging — going gray.

Why does hair turn gray?

Hair goes gray as the pigment inside hair follicles slowly die off. As more pigment dies, the color of the hair strand changes to either gray, white, or silver, according to Kids Health. But first, let’s back up a bit. 

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According to Kids Health, hair consists of two major parts — the shaft and the root. The shaft is the part we see growing out of our head; it’s either short or long, has some kind of texture to it, and is pigmented to look like a color. Maybe black or brown or blonde or red. Then there’s the root, which is the bottom part of a strand of hair — the part that is attached underneath the scalp. 

The root contains tissue, called the hair follicle. Inside the follicle is pigment cells, which determine the color of your hair. Pigment cells — also known as melanocytes — produce melanin, the same chemical that determines our skin color.

So, what happens to pigment cells if our hair is starting to turn gray? Going gray signifies that the pigment cells inside the follicle of the root are dying. This happens usually with age, but you can actually go gray at any age, depending on your genes.

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Is gray hair caused by stress?

is gray hair caused by stress
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Historically, many have thought that hair could be shocked into going gray by trauma or some long-term, great stresses. Generally, scientists have never believed this to be true, and instead considered going gray a universal sign of aging, determined by your genes.

However, a recent 2020 study has flipped the script. While yes, aging and genetics both play a role, a study published by the National Institutes of Health (NIH) found that stress could play a role in affecting stem cells, which are “responsible for regenerating hair pigment.”

According to the study, “Mice were exposed to three types of stress involving mild, short-term paid, psychological stress, and restricted movement. All caused noticeable loss of melanocyte stem cells and hair graying.”

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Ultimately, the study found that the neurotransmitter noradrenaline — also known as norepinephrine — was a key player in the stress-induced mice’s graying hair. 

“By injecting noradrenaline under the skin of unstressed mice, the researchers were able to cause melanocyte stem cell loss and hair graying.”

Why is this significant? Noradrenaline is the neurotransmitter heavily involved in the sympathetic nervous system and it’s “responsible for the ‘fight-or-flight’ reaction in response to stress,” the study adds.

As stress literally stresses out the sympathetic nervous system, “sympathetic nerves extend into each hair follicle and release noradrenaline in response to stress. Normally, the melanocyte stem cells in the follicle are dormant until a new hair is grown. Noradrenaline causes the stem cells to activate.”

The result? The follicle produces no new pigment. The hair produces gray, then white, the study says.

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Does hair turn gray or grow gray?

The myth that hair “turns” gray suggests that our normally pigmented hair eventually transforms into a gray color; but that’s not the case at all.

Hair actually grows gray. When a hair follicle produces pigment and makes the hair, the color of that hair stays as it is. It does not change naturally. (Although you could change it manually by dyeing it.)

When the pigment in a hair follicle starts to die off, there’s less pigment with which to color the new strands of hair with, so the new hairs grow in gray, according to Harvard Health.

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Can you reverse gray hair?

The answer is actually rather complicated; if aging or your genetics is the sole cause of your hair graying, then unfortunately, this natural process cannot be reversed. This is because the pigment cells inside your hair follicle are dying off on their own. There is no way to restore them.

can you reverse gray hair
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However, if your graying hair is the direct result of a certain medical condition, there may be hope for restoring your hair’s natural pigment. 

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According to Medical News Today, various deficiencies in diet could be the cause of premature graying. To reverse gray hair that has been caused by a nutritional deficiency, you can try ingesting more antioxidants — olive oil, fish, fruits and vegetables, green tea — or taking a supplement. Smoking cigarettes has also been linked to premature hair graying; if you suspect that is the cause of your premature hair graying, try to stop smoking.

Other natural methods of reversing graying include applying a mixture of curry leaves and hair oil applied to the scalp, steeping five black tea bags in boiling water and then adding to clean, wet hair, and taking an herbal supplement called Indian gooseberry, which can reverse graying by promoting pigmentation to your hair follicle.

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Can gray hair turn black again?

Again, a complicated answer to a complicated question. If hair has turned prematurely gray because of natural reasons — aging or genetics — then that gray hair will not turn back to its natural color. 

However, hair that has gone prematurely gray due to a medical condition can potentially be reversed or the process of graying slowed down. According to Medical News Today, such medical conditions can include thyroid dysfunction and alopecia areata.

It’s hard to say though, as so much of the reversal process depends on the reason for going prematurely gray in the first place.

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