What Causes Hair To Turn Grey?

Almost everyone will watch their hair turn grey as they approach their golden years. For most people, there isn’t much they can do except grey gracefully or pick out a shade of hair dye they like.

Although it’s not as common, others start to go grey much younger, even before they turn 20. When hair turns grey prematurely, the reason isn’t always obvious. Rumours abound that everything from stress to a good scare can turn your hair grey, sometimes instantly.

We asked four top doctors specialising in hair what causes our locks to turn grey and if there is ever a reason to be concerned. Here’s what they said.

Hair turns grey when it loses a pigment called melanin, Dr. Akhil Wadhera, a dermatologist with Kaiser Permanente in Northern California, explained to HuffPost. Typically, this occurs as part of the normal ageing process starting in your mid-30s to early 40s. However, some people turn grey at a relatively young age.

The most common reason for premature greying is genetics, he said. If your parents went grey at a young age, your hair is likely to turn grey earlier, too.

Nevertheless, some young adults whose parents retained vibrant hair colour into old age experience premature greying for various reasons. Some of those, like genetics, are beyond their control. Others are a result of lifestyle choices or environmental factors.

It’s common for people to say they’re under so much stress that they’re going grey. Although most people make these statements in jest, there is some truth behind them.

“Stress can cause premature greying of hair,” Wadhera said. “In fact, there was a study with over 1,000 young Turkish adults that showed that perceived stress scale scores correlated with premature hair greying severity.”

However, Dr. Ehsan Ali, an internal physician at Beverly Hills Concierge Medicine and Cedars-Sinai Medical Center with specialised training in geriatric medicine, emphasises that acute or chronic stress is required to cause premature greying. “A bad week at work isn’t enough to turn hair grey,” he explained.

That’s because acute stress can trigger a fight-or-flight response, says Dr. Zafer Çetinkaya, head hair transplant surgeon at EsteNove in Istanbul.

When this happens, our bodies release stress hormones, including norepinephrine, he said. Norepinephrine can stop the production of the pigment-producing cells that give our hair its colour. “Once this ‘reservoir’ of stem cells is empty, the follicle can no longer produce colour,” causing hair to gradually turn grey, he explained.

External factors can also cause our hair to turn grey early. “Hair follicles are particularly sensitive to oxidative stressors in the environment such as pollution, ultraviolet light, smoking, hydrogen peroxide and ionising radiation, all of which can result in premature greying,” Wadhera said.

The oxidative stress caused by exposure to these elements “disproportionately affects the cells responsible for hair pigment,” explained Dr. Corey Maas, a hair transplant specialist at the Maas Clinic in California. “Over time, this damage reduces the follicle’s ability to maintain consistent colour.”

However, these external factors typically play only a small role in the greying process. Moreover, how much the environment affects your hair colour depends on several factors that vary widely from person to person, Maas explained.

“Greying is the result of a complex interaction between genetics, cumulative exposure, and how well an individual’s body is able to repair and replace damaged processes of youthful pigmentation,” he said. “The environment can nudge the process along,” but when and how quickly depends on the individual, Maas said.

In horror movies, a character sometimes suddenly develops a streak of white hair after a particularly frightening experience. However, off-screen, hair won’t turn grey instantly, no matter how scared we are.

“The idea of hair turning white overnight from fright is often referred to as Marie Antoinette syndrome,” because the queen’s hair supposedly suddenly turned white before her execution, Çetinkaya said. “In reality, hair that is already outside of the scalp cannot change colour” naturally, he said.

Nevertheless, sudden shock or intense fear can cause hair to go grey over time. Extremely stressful situations can trigger a condition called alopecia areata, Çetinkaya said.

When this happens, “the immune system selectively attacks pigmented hairs, which causes dark hairs to fall out rapidly,” he explained. When a person with some existing grey hair develops alopecia areata, their grey hairs are left behind as their darker hair sheds.

That “creates the appearance of sudden greying,” when what’s really happening is that the loss of darker hair is making the existing grey hair more noticeable, Çetinkaya explained.

Several medical conditions can also contribute to premature greying. “As a specialist, I look for vitamin B12 deficiency, pernicious anaemia, and thyroid dysfunction,” Çetinkaya said.

“These conditions can disrupt the metabolic environment of the hair follicle,” which can result in hair turning grey prematurely. Rare autoimmune conditions such as vitiligo can also target pigment, causing hair to grow in white, he added.

According to Wadhera, low levels of vitamin D3 and deficiencies in minerals such as iron and zinc can also cause premature greying.

If you start greying due to age, there is nothing to worry about except deciding whether to accept your grey hair or visit a salon to choose a new colour.

However, if you start going grey early, before your mid-30s, you may want to investigate. One or two grey hairs usually aren’t cause for concern, Ali said. However, if you notice a proliferation of greys “very early or very rapidly, this can be a clue to look deeper at nutrition, thyroid function, autoimmune issues or lifestyle stressors,” he explained. Your primary care physician can help if you are concerned.

Nevertheless, Ali stresses that going grey isn’t usually a medical or personal failure. Even though there is “a lot of unnecessary fear and marketing around this topic,” going grey is “usually a normal, genetically programmed process,” he said.