Why does hair colour change with aging ?(not going grey)

Factual Questions
1

Quite a few kids of European, but also sometimes Middle Eastern and Central and S Asian origin have light hair, a hair colour which darkens, sometimes to near jet black; my own went from red to brown, to dark brown. WHy does it change? Sometimes the final colour is not there until late pre-teen years, so its not something that changes quickly after birth, like eye colour does.

Why is the reverse not true. I have also seen people, especially those with medium brown hair go well, blonder as they hit their forties, but I am guessing that that’s early part of greying as their hair colour fades it seems to be going blond when its actually slowly losing pigment.

2

I have very blond hair, I am aging now and the few grey hairs I have don’t look grey, they are silver /white. I have hopes that i will have completely white hair in a few years. I think it would be cool! One of my sisters has dark brown hair, as she aged it got lighter and curlier. She hates it. So I guess it is just age and maybe hormone changes that effect hair, that is a assumption, maybe there is a endocrinologist around who might know.

3

I am not a doctor nor scientist…

According to several articles I’ve just found via googling, the answer seems to be that the genes for hair color don’t fully switch “on” until one reaches puberty, and hormonal changes cause the production of “adult” hair pigmentation.

http://www.chicagonow.com/between-us-parents/2013/09/hair-color-darken-change-puberty/

4

In my mind’s eye, I still have the dirty blond hair of my youth/young-adulthood. Whenever I see the dark brown hair fall around me during a haircut, it jars the shit out of me.

5

I was very blonde when I was a little kid, and as I approached adolescence, say 12 or 13, it took on a bit of red, so that some people called me a strawberry blonde. I enhanced this with a red rinse (my mother let me) because I had a sorrel mare at the time. The first time I did it was so we’d match in the rodeo parade. I guess if I’d had a palomino I’d have wanted to go full palomino blonde. I did have a blonde streak in there, always, but I had to part my hair really low on the left for it to show.

And then, unenhanced, it turned kind of sandy. Hair-colored, dirty blonde, light brown? The interesting thing was, when I gave birth to a red-headed kid, my husband actually thought I’d dyed my hair to match him, but the thing was that his color, undeniably red, matched quite a few of the hairs on my head, so when my head was next to his it looked like the same color. I don’t think my hair color changed to match my baby’s!

Another son was born blond but with a red streak right on the top that exactly matched his big brother’s hair. When he was 12 or 13, his hair turned red just as mine did, but the red streak turned into a platinum blond streak so it was like the colors he was born with reversed. It was gorgeous hair. Another son was born blond and it was very light, then it turned quite dark. By the time he was 30 it was almost black. (And he went gray early, maybe because it shows. He has more gray hair than I do, which is peculiar.) I had two blond kids and two redheads and as adults, their hair is all very different colors.

My own hair seemed to get less and less red as I got older, so I put things on it. Actually my hair has been artificially a lot of colors. I haven’t dyed it in about 10 years and the weird thing is that it always looks like it’s going to be gray close to my head, but by the time it’s grown out to my shoulders it doesn’t look so gray. This has been going on since at least 2011, when it looked like I would be totally gray just imminently, but…I’m still not. I don’t know what’s going on. I’m not doing anything now but washing it and conditioning it. It does bleach out some in the summer–always has. I don’t see how that would make it less gray, but maybe it does.Maybe it just makes it less noticeable.

I had a friend who had very dark hair and lots of it. I saw him one year and he had a few silver streaks. A year and a half later I saw him again and it was completely stark white. Not exactly overnight, but that was pretty fast IMO. So…hair is weird and changes all the time.

6

My mom was a platinum blonde as a young child (I’ve seen the pictures). By the time she was a teen, her hair was a dark brown that was almost black. At over 70, it still is, with no grey.

I have medium blonde hair and always have. The only change I’ve noticed with mine was after pregnancy. The texture went from wiry to finer. It’s still weird to me to have silky hair instead of something closer to a horse’s mane.

None of this answer’s the question - I don’t know why this happens.

7

And they also seem to ‘switch off’ starting about the time humans get past reproductive age – that’s when the hair starts to turn grey. Or fall out entirely.

8

My Daddy said, ( family oral history ) his 2 oldest brothers died in WW1. It was on different days and different locations. But the telegrams came the same time informing them of the deaths. Daddy said she went to bed that night and woke up the next day completely grey. Can’t say if it’s true, I just know the aunt’s and uncles all repeat the same tale.

9

I hate to say this, but such a story (and “his / hair turned gray / white overnight due to the shock” isn’t an uncommon wives’ tale) is really unlikely.

The pigmentation that runs through each shaft of hair was placed there in the follicle as the shaft grew. Once hair leaves the follicle, it’s dead tissue.

On average, a human’s head hair grows at about a half-inch per month; given that, the pigmentation in the portion of the hair shaft that’s close to the scalp (i.e., at the root) was placed there fairly recently (say, a few days to a few weeks ago), but if a shaft of hair is, say, 2" long, the portion of the shaft at the tip left the follicle (and had its pigmentation placed) several months ago.

Even if all of your hair follicles suddenly stopped producing pigmentation tonight, the effect of this would appear gradually, as your hair shafts grew out. (It’d look much like how it looks when someone who has gray hair has their hair dyed dark, but then doesn’t dye it again, and after a few weeks, their roots show gray.

The only way to change the entirety of your hair’s color all at once is through chemical coloring.

10

Well, a little googling suggests that, while it’s still incredibly unlikely, there have been a small number of apparently-documented cases of “canities subita” (hair suddenly turning white). This article in The Atlantic indicates that there are 84 known cases (85, including the author’s case) having occurred since 1800. However, of those, only 14 were witnessed by a physician, and not explicable by other mechanisms (like bleaching).