Scientists explain whether hair can turn gray overnight

Natural hair color mainly depends on two types of melanin pigment produced by cells called melanocytes in the hair follicles.

There is eumelanin, which gives hair a black or brown color, and pheomelanin, which gives hair a yellow-red hue. The distribution and ratio of these pigments determines the exact color of the hair, while the absence of melanin leads to white or gray hair, the experts explained to Science Notes.

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During the growth cycle of our hair, melanocytes inject pigment into keratinocytes, the cells that produce keratin, the protein that forms the structure of the hair. Over time, these melanocytes can become less active or die, reducing or completely stopping the production of melanin, leading to graying of the hair.

But the time for graying is not the same for everyone. Many factors influence the process, including genetics, environmental conditions, nutrition, illness and medications, and stress.

Can hair turn gray overnight

There is a link between stress and graying hair, but the idea that hair can turn gray overnight is more myth than reality. More often than not, extreme events change hair color over several days or months.

The biological basis for this phenomenon was revealed in a study published in 2020. The researchers found that stress activates the sympathetic nervous system (our "fight or flight" response system), which causes permanent damage to the pigment-producing cells in the hair follicles.

The reason stress cannot cause hair to turn gray overnight is because of the way hair grows. Hair color is determined in the follicle before the hair grows and becomes visible. Once a strand of hair has grown out of the scalp, its color cannot be changed. Therefore, a sudden or rapid change in hair color is not possible because it requires all the hair to fall out and be replaced with new gray hair, which is a long process.

The phenomenon where people perceive a rapid change in gray hair, often during times of stress, is usually associated with a condition called telogen effluvium. This condition causes predominantly darker (older) hair to fall out, leaving behind gray or white hair and giving the impression of sudden graying. When the hair that has fallen out grows back, it can be gray or have its original color.

As a reminder, scientists believe they have found the reason why human hair loses its color as we age.

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