Dr Karl


Hair Turns White Overnight

Listen to Karl talk about Hair Turns White Overnight

Paul rang in and asked, "How could someone's hair turn white overnight?" I told him it wasn't possible, but I've since discovered that I was actually wrong. 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.

Hair gets its colour from a chemical called melanin, which is pumped in by cells at the base of the hair follicle. As your hair goes grey, these cells at the base stop making melanin. So some hairs will be their normal colour, but some (the ones without melanin) will be completely white. So here's a great truth - there's no such colour as grey hair. Grey hair is dark hairs, with the newer white hairs mixed in.

So how can somebody's hair turn white overnight? Easy, they first have grey hair (which is actually the mix of dark hair and white hair) - and then all the dark hair falls out over a few days.

This could be caused by a disease called alopecia areata , where your hair, for no apparent reason, simply falls out. Unlike common balding, alopecia areata is just as likely to happen in women as in men.

So if you've got grey hair, and those few remaining dark ones bail out, bingo - instant white hair! It can't happen overnight, but it can happen...

© Karl S. Kruszelnicki Pty Ltd 2008.

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