Stress can have a variety of negative effects on the body. The idea that acute stress can cause hair to turn gray is a popular belief. But until now, that link wasn’t scientifically proven.

Hair color is determined by cells called melanocytes, which produce the pigment melanin. New melanocytes are made from melanocyte stem cells that live within the hair follicle at the base of the hair strand. As we age, these stem cells gradually disappear. The hair that regrows from hair follicles that have lost melanocyte stem cells has less pigment and appears gray.