Why Stress Turns Hair Gray Faster Than Age Does
A 2020 study published in Nature by researchers at Harvard University found that chronic stress activates the sympathetic nervous system, which floods hair follicles with norepinephrine. This chemical surge causes melanocyte stem cells, the cells responsible for producing melanin, the pigment that colours hair, to rapidly deplete and migrate out of the follicle. Once those stem cells are gone, the follicle cannot regenerate colour. The hair that grows back is gray or white, permanently. The study was conducted on mice, but the biological mechanism maps directly onto human physiology. For teenagers whose stress responses are already heightened by board exams, social pressure, and disrupted sleep, this depletion can happen years ahead of any genetic timeline.
