As dissertation and deadline stress sweep campuses up and down the country, spare a though for your follicles. In a recent study from Harvard University, scientists have discovered that the link between stress and grey hair is more than just an old wives tale, but is in fact a biological phenomenon.

While grey hair is often associated with ageing, the link between stress and going grey has always been one of association rather than science. However, scientists have now found that stress can actually affect the group of cells in your follicles, known as melanocytes, which produce the pigment that colour your hair. These pigments, known as melanin, influence your hair colour: Eumelanins have a brown/black pigment whereas Pheomelanins have red/yellow pigments, and it is the balance between these pigments that determines your hair colour.

Various illnesses and medications that interfere with this system can in fact lead to a change in hair colour; for example, certain malaria medications lighten hair and conditions like oculocutaneous albinism cause white hair through genetic mutations that completely inhibit melanocytes ability to produce pigment. However, up until now there had been no hard evidence for a link between stress and grey hair.

Scientists at Harvard used a mouse to investigate the effects of stress on fur pigment. The mice in question started the study with black coats, indicating that their melanocytes were producing a normal level of pigment. The mice were then exposed to different levels and types of stress, including being restrained, unpredictable stressors such as cage tilting and rapidly changing light conditions, as well as chemical stress by injecting them with a compound related to capsaicin (the chemical which makes chilli peppers burn). While these experiments do sound rather cruel, and many animal rights activist groups such as PETA have already publicly criticised the study, the scientists did find that the administration of stress did over time increase the number of grey hairs seen in the mice’s coats.

When investigating the mechanism behind this greying effect, the scientists found that the stress led to an overactivity of so called ‘sympathetic nerves’, which are known to be involved in the body’s ‘fight-or-flight’ response. These nerves lead to the release of a chemical called Noradrenaline, and it is this molecule that leads to the pigmentation loss. Noradrenaline leads to an increase in proliferation of melanocyte stem cells present in the hair follicle and following stress this leads to these cells losing their stem cell capabilities and differentiating in a way that prevents them from producing new melanocytes. This then led to the reduction in pigmentation and subsequent formation of grey hairs.

While the reason for a link between stress and melanocytes is not fully understood, the scientists behind the study did propose the idea that it could be a left-over effect from evolution. Animals such as squids and octopi can change their pigmentation as a form of camouflage, particularly when in stressful situations such as whilst encountering a predator. This could explain why stress has such an effect on our hair colour.

So, next time you’re feeling stressed try to relax, your hair may thank you for it!

Emma Dalby

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