A new, small study indicates that there is a strong correlation between periods of high stress and an individual's hair going gray. However, relaxation—during a limited time frame—appears to have the opposite effect, reversing the graying process and re-pigmenting the hair follicles, Diana Kwon writes for Scientific American.

Background and study details

For the study, Martin Picard, a mitochondrial psychobiologist at Columbia University, wanted to explore the "patchwork pattern" by which our cells age by focusing on the graying process for aging hair follicles.

"It seemed like the hair, in a way, recapitulated what we know happens at the cellular level," Picard said. "Maybe there's something to learn there. Maybe the hairs that turn white first are the more vulnerable or least resilient."

Picard and his colleagues recruited 14 men and women, whose ages ranged from 9 to 65 years old and who all had strands of partially gray hair. The individuals provided hair samples of strands that were just one color or which were two colors—with part of the hair strand the participant's original hair color, and another part going gray—from different parts of their bodies, such as the scalp, pubic area, and face.

The researchers then developed a technique that allowed them to digitize and quantify the subtle variations in colors, which they called "hair pigmentation patterns," along each strand of hair. The researchers also investigated the relationship between graying hair and stress in a subset of participants by asking them to recollect high-stress periods of time over the past year and then comparing those instances to the graying pattern on the hair samples they had provided.

Key findings

Right away, the researchers noticed something surprising with the hair pigmentation patterns. In 10 of the 14 participants, participants' graying hairs—from not just their head, but elsewhere across their body as well—had regained color at some points. 

"When we saw this in pubic hair, we thought, 'Okay, this is real,'" Picard said. "This happens not just in one person or on the head but across the whole body."

In a small portion of participants, researchers were able to match stressful events in their lives with times when graying or reversal occurred in their hair strands. For example, a 35-year-old man's hair strands showed signs of reversal during a time that he was on a two-week vacation. Another participant, a 30-year-old woman, had a strand of hair with a white segment that matched a two-month period of high stress when she was going through a marital separation and relocation.

What do these findings mean for your graying hair?

The researchers said their findings indicate that graying hair may be reversible. "What was most remarkable was the fact that they were able to show convincingly that, at the individual hair level, graying is actually reversible," Matt Kaeberlein, a biogerontologist at the University of Washington, who helped edit the study, said. "What we're learning is that, not just in hair but in a variety of tissues, the biological changes that happen with age are, in many cases, reversible—this is a nice example of that."

However, the researchers cautioned that while graying may be reversible, there is likely only a small window of time when the change can occur—namely, in people's late 20s or 30s, when graying first begins, according to Ralf Paus, a dermatologist at the University of Miami and one of the study's co-authors.

In a full head of gray hair, most strands have probably reached "a point of no return," he added, although there is a possibility some strands can still undergo a change in color.

Separately, Eva Peters, a psychoneuroimmunologist at the University Hospital of Giessen and Marburg in Germany, who was not involved in the research, said while the study was "very creative and well-conceptualized," more research was needed to confirm the findings, given the relatively small number of cases in the study.

Meanwhile, Picard, Paus, and other members of the team said they plan to look more closely at the association between stress and graying by tracking people over a specific time frame. This will allow the researchers to examine the issue in real time rather than retrospectively.

Because hair is a "physical record of elapsed events" like the rings of a tree, Picard suggests that in the future, hair may be used to assess how life events affect aging. "It's pretty clear that the hair encodes part of your biological history in some way," he said. (Kwon, Scientific American, 6/22)