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My hair is usually brown and black, I haven't dyed my hair for two years and if I had this would be strange. A strand of hair went from black(roots) grey (middle) then light brown(bottom).

How does hair change color along its length? And why does this happen?

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  • $\begingroup$ I am curious about this too! I am naturally blonde, and on some of the strands of my hair I have random sections of red, then it goes back to blonde. $\endgroup$
    – Sarah
    Feb 17, 2022 at 23:20

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Your hair gets its color from a compound known as melanin, produced by special cells called melanocytes. There are two versions of melanin - one that produces dark pigmentation and the other that produces light pigmentation. If your natural hair color is brown/black, then it normally has a specific amount of dark vs light pigment. The middle section of this hair is grey because there was an absence of melanin production when the hair was still growing. There could be multiple factors (including stress , as described on the library of congress site), but it's nothing to worry about. Your melanocytes started to normally produce melanin again, which is why the newest hair growth (closest to the roots) is dark in color (dark brown/black).

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  • $\begingroup$ Hi, @Kate. This is a good answer, thanks. I've often heard about the stress link with grey hair. Could you provide a citation to it? Could you provide a citation about the temporary lack of melanin production. I know some people produce a grey hair once in a while, but I thought the whole hair would be grey, not a section. Generally, on this site citations are useful for good answers. $\endgroup$
    – James
    Mar 8, 2017 at 7:11
  • $\begingroup$ Sorry - new here, didn't know! Here's a useful link: loc.gov/rr/scitech/mysteries/grayhair.html $\endgroup$
    – Kate
    Mar 8, 2017 at 7:36
  • $\begingroup$ Welcome to Bio.SE :). I added the link into your answer. I have a feeling that this question will be closed though since it might be medical related. $\endgroup$
    – James
    Mar 8, 2017 at 11:19
  • $\begingroup$ It has recently been found that hair greying can be reversible in humans. elifesciences.org/articles/67437 $\endgroup$
    – Brian Ó Maoláin
    Feb 23, 2022 at 2:15

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