Why Hair Darkens with Age

Many people notice that they are born with light hair, which often darkens by adolescence — and this is completely normal. The main reason for these changes is that the amount of melanin, the pigment that colors hair, skin, and eyes, changes with age.

Two types of pigment determine hair color: eumelanin makes hair dark, while pheomelanin gives it a reddish tint. These pigments are produced by special cells called melanocytes, whose activity depends on genes and hormones. During puberty, previously inactive genes are switched on, and hair can noticeably darken.

Over time, melanocytes become less active and regenerate more slowly, leading to a decrease in melanin. This results in gray or completely white hair. For some people, this happens earlier, for others later, and the timing is often inherited.

Stress can also affect hair color. Strong emotional experiences, illnesses, or sudden changes in the body can sometimes cause temporary hair loss, and new strands may grow in lighter. Animal experiments have shown that stress can reduce the number of melanocytes in hair follicles, causing mice’s fur to turn gray more quickly.