Is it true that stress can cause our hair to turn gray? For decades, scientists could not figure out how this happens, often theorizing that stress hormones such as cortisol must play some role in the process.
However, researchers have finally discovered where graying comes from, and the answer lies in hair cells called melanocytes. Melanocytes are a type of cell that determines the amount of melanin in a given hair follicle. These cells define our hair color and are derived from melanocyte stem cells (MeSC), which are located in a part of each hair called the bulge.
As we age, the number of MeSC’s gradually depletes, leaving us with increasingly less color until all MeSC’s are gone, turning our hair completely gray, then white. There are other ways our hair can turn gray besides aging, including malnutrition, disorders like vitiligo, but the most common reason is stress.
In a study published by the journal Nature, Bing Zhang, et al. discovered that our sympathetic nervous system (SNS), which is responsible for the “fight-or-flight” mechanism, is the key to understanding how stress causes our hair to change color.
As the SNS releases high amounts of noradrenaline in response to stress, the hormone agitates MeSC cells, accelerating their depletion. In contrast, suppression of noradrenaline from the SNS of mice prevented whitening under stress.
“Here we report that, in mice, acute stress leads to hair greying through the fast depletion of melanocyte stem cells…hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche.” – Bing Zhang, et al.
Unfortunately, after all MeSC’s have depleted from a hair follicle, they never come back. “And once they’re gone, the pigment cannot be generated anymore,” says Ya-Chieh Hsu, a professor of stem cell and regenerative biology at Harvard.
Now that we understand what causes our hair to turn gray, it’s likely that companies will jump on this discovery in an attempt to sell products that claim to prevent hair graying.
Other studies have highlighted the dangers of hair dyes, specifically in their ability to increase a patient’s risk of breast cancer.
However, it’s interesting to think about why hair turns color in the first place. Some theorize that whitening occurs to signal trust, leadership, and experience to other members of the community. Hair whitening may actually be an evolutionary advantage that places older individuals in a position of authority due to their perceived experience by others in the community.
We can observe this quality in male silverback mountain gorillas, which often only lead a gorilla troop after reaching a mature enough state that facilitates hair whitening.
Or, it is equally possible that white hair is a signal to younger individuals that you are no longer reproductively capable or of an age to take care of potential offspring.
Perhaps both are true. Regardless, this discovery opens up an interesting discussion about community, the advantages or disadvantages of having white hair over colored hair, and the broader implications (and dangers) of hair coloration as a whole.
Author: Phillip Schneider is a student as well as a staff writer and assistant editor for Waking Times. If you would like to see more of his work, you can visit his website, or follow him on the free speech social network Minds.