As a subject matter expert in dermatology, I can provide you with an informed response to your question about hair turning white overnight.

While it's a common myth that someone's hair can turn white overnight due to extreme stress or trauma, this is not scientifically accurate. Hair color is determined by the presence of pigments called melanin, which are produced by cells called melanocytes within the hair follicle. The process of hair growth involves the cells in the follicle dividing and pushing the older cells up the shaft of the hair. When the hair is exposed to the surface, the cells are no longer alive and the pigment production stops.

For hair to turn white, the melanocytes would have to stop producing melanin. This can happen gradually over time with aging, as the melanocytes naturally decrease in number and activity. However, for this to happen to all the hair follicles at once, which would be required for hair to turn white overnight, is highly unlikely. Stress can potentially affect the immune system and lead to conditions like alopecia areata, where hair falls out in patches, but it does not cause the hair to lose its color.

In conclusion, while the idea of hair turning white overnight is a popular notion, it is not supported by scientific evidence. Hair color change is a gradual process and cannot occur as rapidly as folklore suggests.

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It's because of a skin disease called alopecia areata. The hair can't actually turn white overnight, because all the hair is "dead", and the only way you can make its colour change is with dyes. ... So some hairs will be their normal colour, but some (the ones without melanin) will be completely white.read more >>