As we get older, the stem cells that keep our hair colored might stop working properly because of problems in their internal repair system, and once they're gone, our hair turns gray for good.

Going gray might happen because the stem cells that give rise to hair color cells get damaged over time, not because the color-making cells themselves stop working. Keeping these stem cells healthy could be key to keeping your hair colored as you age.

As we age, the stem cells that give color to our hair can start acting up — they might turn into pigment cells too soon or in the wrong place, which could be why our hair turns gray.

Going gray might happen because the stem cells that keep your hair colored stop working properly as you age, according to studies in people and specially tagged mice.

Going gray might happen because the stem cells that keep your hair colored aren't working properly as you age.

As we get older, the cells that give hair its color start to die off because of stress and lower levels of a protective protein, which is why hair turns gray and doesn’t grow back colored.