Discovering that Hair Greying is Reversible
How Mitochondria May Be Involved in Stress-Induced Hair Greying
ENERGY SCIENCE
Full-Text Link to Primary Source
Looking at my reflection in the rearview mirror with morning sunlight streaming through the windows, it’s now hard to ignore the shimmering strands of silver that seem to be multiplying on my head. You may have seen this happen to your parents, friends, pets, and perhaps even yourself?
Is hair greying linked to life stress?
What if this was reversible?
Hair Growth and the Role of Mitochondria
Like everything else in biology, hair growth requires energy.
The growth of a strand of hair begins below the surface of your skin in a structure called a hair follicle. During the growth process, new material from within the follicle are incorporated into the hair shaft. These materials include cells, proteins, and other molecules, and they are influenced by the chemical and electrical environment of the hair follicle. Here is what Wikipedia says hair follicles look like.
Here is what they actually look like when you pluck them from your colleague’s head and slap them on a glass slide on the microscope:
Mitochondria contribute to the energetic processes needed to support follicles and organelles called melanosomes. Melanosomes contain the pigment melanin, made by specialized cells in the hair follicle called melanocytes.
As a hair grows out of your scalp, the hair shaft hardens, preserving the components of your hair in a solid, stable form. The colorful pigment, melanin, is incorporated into hair shafts as they grow, giving your hair its characteristic color. And that too, costs energy.
The composition of your hair over its length can provide information about changes that occurred within your hair follicles (or your body more broadly) across time. It’s similar to how tree rings can give us information about what a tree’s environment was like over the course of its growth.
The features of strands of hair could potentially be matched to timelines of life events to better understand a person’s biological history, including what may be contributing to hair greying. That’s why you can use hair for drug testing or toxicant exposure over the last few months.
Why Hairs Turn Grey
The pigment-producing system in the follicle gradually declines with age, leading to grey or white hair. The impacts of internal factors, such as genetics and oxidative damage, and external factors, such as exposure to pollution or ultraviolet radiation, can accumulate over time and contribute to hair greying.
Because of their role in oxidative metabolism, mitochondria also likely lead to oxidative stress in the hair follicle.
We also know that stress affects the body in measurable ways. Psychological stress is not just a feeling. It triggers the release of hormones, changes in metabolism and immune signaling, and other molecular changes within our cells.
Studies in mice have shown that stress, particularly activation of the sympathetic nervous system responsible for our “fight or flight” response, can accelerate hair greying.
With the fast stem cell division in follicles triggered by stress in mice, hair follicles run out of the stem cells that turn into melanin-producing cells more quickly. Without these stem cells, mouse hair follicles can’t produce more melanin, and the hair permanently turns grey.
But similar kinds of studies aren’t possible in humans, and findings from animal models don’t always exactly match what happens in humans.
Could acute stress actually cause hair greying in humans? And if so, once a follicle loses pigmentation, is the change permanent?
When we started looking for an answer in the scientific literature, we found two reports of individual cases of hair color changes and repigmentation in humans (in response to drug treatments).
But this phenomenon hadn’t been studied quantitatively in healthy people.
Mapping Hair Color and Life Events
To begin our exploration, we collected 397 hair samples from 14 healthy women and men who generously agreed to participate in our study. That part was relatively easy.
The tricky part was developing a way to map tiny changes in hair color over time at the level of a single human hair. Ayelet Rosenberg, an outstanding student in the lab, tackled this as part of her neuroscience thesis work at Barnard.
In essence, the way Ayelet imaged hairs was by capturing images of whole hairs, their shafts, and their follicles. She digitized each hair with a high-resolution scanner like we use to do with printed photos. And then measured each pixel across the length of each hair image to see how light or dark the pixels were.
That yielded the Hair Pigmentation Pattern (HPP). Here is a video of the most remarkable hair we studied—it was dark, lost pigmentation for about two centimeters (roughly one inch)… until it regained pigmentation.
Hair greying is reversible!
To understand what’s happening “under the hood” in the greying hair follicle, we performed two proteomic experiments on single hairs to understand how hair color (grey versus not) related to the presence and volume of different proteins.
In the first experiment, we looked at proteins in matched dark and white hairs collected at the same time from a male and a female participant of about the same age. The second experiment involved validating these results by analyzing white and dark hairs from six individuals using a separate proteomic platform and in another lab.
The results showed that grey hairs have more—not less—mitochondrial proteins. In other cases, as in aging, that’s a sign or a response to hypermetabolism. When something starts to cost more energy, cells respond by making more mitochondria.
Could hair go grey because they run out of energy, facing energy constraint?
What We Learnt About Hair Greying
The first major finding was that hair greying can happen quickly within a single hair growth cycle. Some hairs showed sharp transitions from dark to grey along the same strand. This suggests that a follicle can switch from producing pigmented hair to producing hair without pigment over a relatively short period due to loss of melanosomes.
Biology exhibits such plasticity!
The second major finding really surprised us. Some hairs naturally regained pigment. In other words, the same strand could show white hair followed by darker hair closer to the root, meaning the follicle had resumed producing pigment after a period of greying. Here is an example.
This didn’t just happen to hair on people’s heads, but we also saw it in beard and pubic hair. It was then that we knew that this phenomenon had to be real!
The third major finding was molecular. White hairs showed changes in proteins related to energy metabolism, mitochondria, melanosome biology, and antioxidant defenses. This suggests that greying is not just a cosmetic change.
It appears to involve deeper shifts in the energetic and metabolic state of the hair follicle, and mitochondria are likely playing a role.
The fourth major finding connected hair pigmentation to psychological stress. In a few participants, the timeline for hair graying and reversal events coincided closely with periods of high- and low-stress, respectively.
In one participant, multiple hairs regained pigment around the same period that he reported a major reduction in stress after a vacation.
In another participant, a hair showed a temporary period of complete greying that corresponded to an intense two-month period of life stress, followed by repigmentation after that stressful period ended (see figure below).
Based on our mathematical simulations of hair greying, we proposed a threshold model that explains these situations. The idea is that each follicle may accumulate an “aging factor” over time. Excess energy expenditure, or hypermetabolism, perhaps.
If a follicle is far below the greying threshold, stress may not visibly affect it. If it is already near the threshold, stress may push it over the edge into greying. If the stressor resolves and the follicle falls back below the threshold, pigment production may resume.
This model helps explain why a young child is unlikely to suddenly go grey from a stressful event, while a middle-aged adult with follicles already near the greying threshold might show more visible changes.
What These Results Mean For Our Lives and the Aging Process
This study gives us a vivid example of how life experience may become biologically embedded. It shows how stress-related biology may have visible and measurable impacts on the body.
Our research also reminds us that aging is not always a straightforward one-way process. At the level of individual cells and tissues, some features of biological aging may be more dynamic, responsive, and malleable than we thought.
Systems within our bodies can weaken, recover, adapt, and sometimes partially reverse course. That said, not everyone can reverse their grey hair by just reducing stress. There is a window of opportunity for each hair—and likely for different people.
However, the findings do suggest something powerful: Our cells are constantly responding to experiences in our lives—stress, recovery, energy demand, rest, and resilience.
Using the hair pigmentation patterning method, hairs serve as a sort of archive that documents how our biology has been shaped by recent life events. Monitoring changes in hair color over time could help us evaluate the effectiveness of treatments to reduce stress or slow aging.
But perhaps most importantly, this paper invites a more nuanced view of aging than is typically assumed. Aging isn’t just the slow, pre-programmed, inevitable fading in our vitality. Aging is an energetic process.
In many ways, aging is emerging as the product of a dynamic conversation between our cells and our environment—one shaped by stress, adaptation, and the possibility of renewal, integrated at the level of energy.
Interested in what the Mitochondrial Psychobiology Group has been up to lately?
Visit our website to learn about our research, browse our latest papers, and meet the amazing people who make this research possible.
As a redhead in my late 20s, I was concerned that my hair was beginning to turn white earlier than expected. By the beginning of last year, I had noticed more white hairs than I was comfortable with. Being involved in research, I decided to investigate the biological processes responsible for melanin production in hair. Once I identified several nutrients and pathways involved, I began supplementing accordingly and was surprised to see a significant reversal of my white hairs.
You could say I conducted a small self-experiment. Needless to say, your article was particularly interesting because it highlights findings that align with my own observations—namely, that reversal of gray or white hair can occur relatively quickly under the right conditions.
On a related note, one of the most important conclusions from my experience was that nutrient and vitamin deficiencies appeared to be the underlying cause of my hair depigmentation. While my experience is purely anecdotal, I believe this is an area that warrants further investigation, as nutritional status may play a larger role in premature graying than is often appreciated.
But I like my grey hair.