Researchers from Columbia University, U.S.A, have found evidence of human hair turning grey due to stress and then reverting to its natural colour when the stress was removed.
Several years back, a widespread theory suggested that stressful events can lead to loss of hair and colour, but until now, it was believed that such greying was irreversible.
In this new study, the researchers found evidence of stress-related greyed hair reverting to its natural colour once the stressful event ended.
The team, studied the role of melanin and certain proteins play in giving hair its natural colour. They asked 14 volunteers to allow them to remove 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 colour.
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 colour.
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 colour.
From their findings, the scientists noted that stress can, indeed, lead to greying hair, and that removing the stress factor can allow the hair to return to its natural colour.
They stated that 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.
