In a new study, the authors collected hair from 14 people of various ethnic backgrounds, specifically looking for gray at the root, but with colored tips. To their amazement, scientists discovered that numerous hairs became less gray towards the root, suggesting that they were somehow regaining their original color.
By carrying out an analysis of the collected samples in order to ascertain the different protein profiles of gray and colored hair, the results showed that gray hair contained a large number of proteins normally involved in energy metabolism. Many of these proteins are also known to be upregulated in response to stress and have been associated with various other age-related features such as DNA degradation.
Many of these effects can be reversed by lifestyle changes, such as regular exercise or switching to a healthier diet. Thus, the researchers asked participants to report the most stressful episodes of their past 12 months, suspecting that it could play a primary role in hair graying.
The results showed that color return has always been related to particularly low stress periods: hair grows at a speed of about one centimeter, a woman’s hair sample included a 2 centimeter gray band, which turned out to be attributed to a period of severe stress that lasted two months. Another participant regained the original color of his hair during a two week vacation.
The researchers found that a hair can become completely gray or undergo a complete reversal of the process in just 3.7 days, although on average it takes about three months for these changes to occur. The team only looked at individual hairs, and not an entire head. According to them, however, “human aging is not a linear and irreversible biological process and can, at least in part, be interrupted or even reversed“.