A team of researchers at Columbia University, collaborating with an associate at the University of Miami Miller School of Medicine, has found evidence of human hair turning grey due to stress and then reverting to its natural color when the stress was removed. They have written a paper detailing their findings and have uploaded it to the bioRxiv preprint server.
For many years, conventional wisdom has suggested that stressful events can lead to loss of hair color, but until now, it was believed that such greying was irreversible. In this new effort, the researchers have found evidence of stress-related greyed hair reverting to its natural color once the stressful event ended.
The researchers were studying the role melanin and certain proteins play in giving hair its natural color. They asked 14 volunteers to allow them to pluck hairs from their head and some other body parts. The researchers collected 400 hair samples and analyzed them using a new imaging technique that detected pigment levels in different parts of the hair. They found that some of the hairs were grey on the tips rather than the roots.
Hair grows from the roots; thus, the finding by the researchers suggests that the hair had turned grey at some point and then at a later date, resumed growing in its natural color. Upon their discovery, the researchers contacted the same 14 volunteers and asked them to come back and answer some questions. Because hair grows at a certain rate, the researchers were able to calculate how far back in time a person's hair had started to turn grey, and then when it had reverted to its natural color. They asked the volunteers if they had experienced stressful events on or around the time the hair had turned grey, and found several matches. They also found that for one person, going on vacation had coincided with their hair reverting to its natural color. The researchers suggest their findings indicate that stress can, indeed, lead to greying hair, and that removing the stress factor can allow the hair to return to its natural color. They note such reversion appears to apply only to hair that has turned grey from stress and only if it occurs relatively soon after the hair has turned grey.