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.
Although it’s mostly down to the natural ageing process and genes, stress can also play a role.
But scientists were not clear exactly how stress affected the hairs on our heads.
‘Damage is permanent’
Pain in mice triggered the release of adrenaline and cortisol, making their hearts beat faster and blood pressure rise, affecting the nervous system and causing acute stress.
This process then sped up the depletion of stem cells that produced melanin in hair follicles.
“I expected stress was bad for the body,” said Prof Hsu.
“But the detrimental impact of stress that we discovered was beyond what I imagined.
“After just a few days, all of the pigment-regenerating stem cells were lost.
“Once they’re gone, you can’t regenerate pigment any more – the damage is permanent.”