A new study reports that stress does indeed gray out your hair. The good news, however, is that it will also revert to its original color after the stress is removed.
While the paper hasn't yet been published in a scientific journal, and as such has not yet been peer-reviewed -- so take the findings with a grain of salt.
Folk wisdom has held that stress can lead to hairs turning gray. But what we've always known intuitively, and through our grandmothers' rants, seems to be rooted in scientific fact, according to a new study.
The team aimed to investigate how melanin and other proteins in strands of hair interact to create its natural color. They collected around 400 samples of hair from various areas of the bodies of 14 volunteers and analyzed them using an imaging technique designed to detect pigment levels in different parts of the strands.
Some of the hairs thus investigated were gray at the tips rather than the roots, the team explained. Given that strands of hair grow from the root up, this suggests that the hair was gray to begin with but returned to its natural colors at a later date.
Following this realization, the authors called the participants back to answer some questions. First, they calculated when the hairs turned grey and how long had passed since they reverted to their natural color (because hair grows at a constant rate). Then, they asked the volunteers if they had experienced any stressful events around that time, finding several matches.
For one person, the time when their hair returned to its natural color coincided with vacation, suggesting that it was a drop in stress levels that promoted this shift. They do note, however, that only hair that turned grey due to stress will revert to its colors when mental state improves. However, they also explain that this shift back only seems to occur if the drop in stress occurs relatively soon after the hair turned grey.
As I've already mentioned, the study has not been peer-reviewed yet, so we don't yet know the validity of these findings. But they do align well with folk wisdom and anecdotal evidence, so they could hold a kernel of truth.
The study "Human Hair Graying is Naturally Reversible and Linked to Stress" has been published in the pre-print journal bioRxiv.