Researchers at Columbia University and elsewhere say they’ve found a way to track the graying of a person’s hair over time. It’s a discovery that also suggests stress really can turn people’s hair grey or white, and that relieving this stress can then turn the colour back on, at least up to a certain point.
We obviously tend to lose hair colour the older we get, as the cells in our hair follicles stop producing the pigment melanin. But there have long been anecdotal reports of even younger people’s hair losing colour almost immediately after experiencing stressful events. And while some of these incidents are probably just folk tales, there have been hundreds of these individual cases documented by doctors too. More recently, animal studies, often in mice, have also backed up the existence of this phenomenon.
But mice, as we’re fond of saying here, are not people. So although hair graying happens in all sorts of mammals, the process might look different in important ways for humans, including stress-related graying. This new study, published this week in the journal eLife and led by researchers from Columbia University’s Vagelos College of Physicians and Surgeons, seems to be one of the first to try quantifying how our hair turns grey.
The hair that’s visible on the head isn’t living — it’s a keratin-rich filament that’s slowly produced and pushed out by the hair follicles underneath the skin. And thanks to a new technique developed by the researchers, the team was able to collect and compare tiny slices of a single hair strand from participants. These slices of hair could then be used like the rings inside a tree, indirectly showing the health of the follicle as it created the strand over time, including the status of their pigmentation.
“If you use your eyes to look at a hair, it will seem like it’s the same colour throughout unless there is a major transition,” senior author Martin Picard said in a statement from the university. “Under a high-resolution scanner, you see small, subtle variations in colour, and that’s what we’re measuring.”
Picard and his team studied almost 400 individual hairs taken from 14 healthy volunteers, ages 9 to 39. The subjects also filled out a stress diary, where they would rate the level of stress they had experienced during any given week. In some of these volunteers, the team was able to spot gradual graying along a hair strand, while a few seemed to lose and then regain colour over time. And when they cross-referenced this off-and-on colouring to people’s reported stress levels, they found a solid correlation between the two, to the point where one person regained colour in some of their hairs during a very clear moment of relaxation.
“There was one individual who went on vacation, and five hairs on that person’s head reverted back to dark during the vacation, synchronised in time,” Picard said.
The findings are based on a small sample size, so they shouldn’t be seen as definitive. But they could provide some important insights into how hair graying occurs in humans if they turn out to be further validated. Other recent research in mice has suggested that once graying happens, it’s pretty much irreversible afterward. But this research suggests that there’s a more flexible brink of graying in people, where stress could tip the scales one way or another.
Aside from simply studying the colour of a hair strand over time, the researchers also found subtle changes in protein levels in hairs that lost colour. And all the data was used to create a mathematical model of stress-related graying — a model they hope could one day help scientists track how people’s recent life experiences affect their health. Just don’t expect your next vacation to suddenly restore your well-grayed hair back to a vibrant colour, especially the older you are.
“In middle age, when the hair is near that threshold because of biological age and other factors, stress will push it over the threshold and it transitions to grey,” Picard said. “But we don’t think that reducing stress in a 70-year-old who’s been grey for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the grey threshold.”