Does stress cause grey hair? What the research shows

Stress may influence when hair loses its colour, but research does not support treating every new grey strand as evidence of too much pressure. An explainer published by Medical News Today draws together animal and human findings that point to a biological connection, while leaving important questions about permanence unanswered.

For people also noticing hair loss, the distinction matters: changing colour and losing density are different processes. The research concerns the cells responsible for pigment, not a treatment for thinning hair. Its most intriguing human finding — that some individual hairs regained colour — comes from just 14 participants.

What happened

The evidence described by Medical News Today includes two studies asking different questions. A mouse experiment published in 2020 investigated how stress could disrupt pigment production. A small human study in 2021 examined changes in colour along individual hairs. Neither was a trial of a treatment for grey hair.

In the mouse research, the key chemical was noradrenaline, also called norepinephrine. It helps transmit signals in the body's stress response. Researchers found that increased signalling caused normally resting melanocyte stem cells to become active rapidly, exhausting the supply available to support future hair colour.

Melanocyte stem cells are reserve cells that give rise to melanocytes, the cells that make melanin. Melanin is the pigment responsible for hair colour. Losing that reserve means a follicle — the structure in the skin that grows a hair — can no longer replenish its pigment-producing cells in the usual way.

The animal findings therefore offer a mechanism for lasting colour loss. However, demonstrating that process in mice does not establish how much everyday stress contributes to human greying, or whether a particular stressful event explains a person's changing hair colour.

The human study provided a different observation. According to Medical News Today, researchers examined hair from 14 participants aged nine to 65 and identified some strands in which pigment had returned. Colour reversal was observed in hairs from the scalp, face and body, rather than being confined to scalp hair.

Not every grey hair regained colour. The small sample cannot show how common this is across the population, and the findings do not establish a dependable method for producing it. Observing a change in individual strands is also different from demonstrating that an entire head of grey hair can become darker again.

The background

Hair receives its pigment while it is being formed inside the follicle. Once the shaft has emerged from the scalp, it is made of non-living material. A change in the follicle's pigment production therefore affects newly formed sections of hair, rather than recolouring the full length already visible.

Hair growth follows a repeating cycle. The active growth stage, called anagen, can last several years. A brief transition stage, catagen, follows, before the resting stage, telogen, which usually lasts a few months on the scalp. Different follicles move through these stages at different times.

Age remains the main explanation for greying, with genetics helping determine its timing. Many people notice their first grey hairs in their 30s or 40s, while others see them earlier or later. Starting younger than a friend or partner does not, by itself, establish a nutritional deficiency or illness.

Greying and pattern hair loss can occur together without sharing the same immediate cause. In androgenetic alopecia, the medical name for pattern hair loss, susceptible follicles gradually produce finer hairs. Our guide to male pattern baldness, its signs and treatment options explains that separate process.

Stress can also trigger telogen effluvium, a form of widespread shedding caused when more hairs enter the resting phase. It often becomes noticeable a few months after a trigger. That delay can make the connection difficult to recognise, but this is not the same mechanism as losing pigment-producing cells.

Other conditions sometimes affect colour. Vitiligo, an autoimmune condition in which the immune system attacks pigment-producing cells, can cause white patches in both skin and hair. Alopecia areata, which involves an immune attack on hair follicles, can also be associated with changes in hair colour, including during regrowth.