Scientists say they may have discovered why stress makes hair turn white, and a potential way of stopping it happening without reaching for the dye.
In experiments on mice, stem cells that control skin and hair colour became damaged after intense stress.
In a chance finding, dark-furred mice turned completely white within weeks.
The US and Brazilian researchers said this avenue was worth exploring further to develop a drug that prevents hair colour loss from ageing.
Men and women can go grey any time from their mid-30s, with the timing of parental hair colour change giving most of the clues on when.