Gray hair is one of the most obvious signs of aging, but it does not simply mean the hair follicle has stopped working. A gray or white hair can still grow normally—the only difference is that the follicle is producing less melanin, the pigment responsible for the color of the hair.
Many people wonder whether red light therapy restores hair color.
Red-light therapy (RLT), also known as photobiomodulation or low-level light therapy, has drawn attention because of its possible effects on hair follicles. Research suggests that RLT may help promote hair growth in some cases of hair loss. Yet increasing hair growth and restoring the pigment within the hair are two separate biological processes.
Why Hair Turns Gray in the First Place
As people get older, these pigment-producing cells, melanocytes, become less active. [2,3] The follicle may then produce less melanin, causing newly growing hair to turn grey. When pigment production drops to an extremely low level or stops altogether, the hair will become white.
Several factors influence hair graying, including genetics, aging, oxidative stress, and changes in the pigment-producing system within the hair follicle. [2,3,4] Researchers have found changes relating to melanocyte stem cells, which play a role in maintaining the number of pigment-producing cells over time. [3]
This matters because gray hair does not merely involve the hair shaft itself; the fundamental changes take place within the follicle.
Once a hair has grown out from the scalp, its color cannot be altered biologically from within; any possibility of re-pigmentation would therefore have to occur in the follicle as it produces a new hair. [5]
Hair Follicle Growth and Hair Pigmentation Are Different Processes
A common misconception about RLT and gray hair is that any treatment that promotes hair growth will also improve hair color. However, that isn’t how it works.
Hair growth is driven by hair follicle activity and its growth cycle, while hair color depends mainly on melanocytes and the production and transfer of melanin. [3] A treatment might cause a follicle to produce thicker or longer hair without making it darker.
It is especially important to note this since low-level light therapy has been researched as a treatment for hair loss, particularly androgenetic alopecia. [1] A systematic review and meta-analysis showed that low-level laser and LED therapy can lead to an increase in hair density in certain types of alopecia. Yet the studies mainly assessed outcomes like hair density, not the restoration of gray hair pigment.
In other words, the fact that red light might help hair to grow doesn’t simply mean that it can make gray hair dark again.
How Melanocytes and Melanocyte Stem Cells Produce Hair Color
Melanocytes produce melanin through a biological process involving enzymes like tyrosinase and regulatory proteins such as MITF, and then transfer pigment to developing hair-forming cells, giving the growing hair its color. [3,4]
Hair follicles also contain melanocyte stem cells, which function as a reservoir of pigment-producing cells during subsequent hair-growth cycles. [3] As people get older, this system may become less effective.
Research shows that oxidative damage and changes in the hair follicle environment can harm melanocytes, the cells that produce pigment. [3,4] This can lead to fewer pigment-producing cells.
This helps explain why reversing established gray hair is difficult.
If the melanocytes are still there but less active, it might be possible to restore function and achieve repigmentation. But if the pigment-producing system is severely depleted, merely stimulating the follicle may be insufficient.
Could Mitochondrial Function or Oxidative Stress Affect Graying?
Oxidative stress is one of the main biological mechanisms currently being studied in hair graying.
Reactive oxygen species are naturally produced as a result of metabolism. Usually, the body’s antioxidant systems manage these substances. But when a person is aging or when the cells are under stress, oxidative damage can build up.
Melanocytes in the hair follicle seem especially susceptible to oxidative stress, and the damage they suffer can affect their ability to survive, produce pigment, and maintain their stem cells. [3,4]
Mitochondria, which produce much of a cell’s energy, also play a role in cellular metabolism and maintenance of oxidative balance. Because photobiomodulation can affect cell signaling and mitochondrial activity, some studies suggest that red or near-infrared light may have biological effects on follicle health. [6]
What Evidence Exists for Red-Light Therapy and Hair Repigmentation?
Low-level light therapy has shown promising results in promoting hair growth for some types of hair loss. [1] The American Academy of Dermatology notes that repeated red-light treatments may help with hereditary hair loss. [7] But hair repigmentation is a different question.
To date, clinical studies on red light/low-level light therapy have primarily evaluated hair growth and density rather than restoration of gray or white hair pigmentation. [1]
Recent studies have explored experimental methods aimed at activating follicular melanocytes and restarting melanin production. Yet these methods are still very different from just using a consumer red-light device at home. [4]
Although RLT may increase hair density or thickness, this should not be interpreted as evidence of restoration. It’s normal for hair color to change, and individual hairs can undergo variations in pigmentation throughout their growth cycle.
When Premature Graying May Have Causes Beyond Normal Aging
Gray hair does not always result from normal aging.
Some individuals notice gray hair at a young age. Although genetics plays an important role, researchers have also looked into links with nutritional deficiencies, smoking, oxidative stress, and some medical conditions.
Studies have found links between premature graying and factors such as vitamin B12, vitamin D, ferritin, and smoking, even though these associations do not mean adjusting one of these factors will restore hair color. [4]
It would be reasonable to consult a dermatologist or healthcare professional if gray hair appears early, advances quickly, or occurs with other symptoms.
Final Thoughts
Can RLT reverse gray hair? There is a stronger research foundation for using RLT to promote hair growth in some cases of hair loss; however, gray hair relates to a different biological system—melanocytes and melanocyte stem cells responsible for producing and maintaining pigment. At present, RLT is still under investigation as a possible solution for gray hair and has not been proven to work.
Further clinical trials are required to determine whether this therapy can restore natural hair color. Stay tuned for updates as research progresses!
References
[1] Perez SM, Vattigunta M, Kelly C, Eber A. Low-Level Laser and LED Therapy in Alopecia: A Systematic Review and Meta-Analysis. Dermatol Surg. 2025 Feb 1;51(2):179-183. doi: 10.1097/DSS.0000000000004442. Epub 2024 Oct 15. PMID: 39404126.
[2] Herdiana Y. Gray Hair: From Preventive to Treatment. Clin Cosmet Investig Dermatol. 2025 Jun 17;18:1475-1494. doi: 10.2147/CCID.S526263. PMID: 40546989; PMCID: PMC12182098.
[3] Paus R, Sevilla A, Grichnik JM. Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers. J Invest Dermatol. 2024 Mar;144(3):474-491. doi: 10.1016/j.jid.2023.09.276. Epub 2023 Dec 13. PMID: 38099887.
[4] Desai DD, Karim M, Nohria A, Needle C, Brinks A, Kearney CA, Ridge A, Mesinkovska N, Shapiro J, Lo Sicco KI. Premature hair graying: a multifaceted phenomenon. Int J Dermatol. 2025 May;64(5):819-829. doi: 10.1111/ijd.17580. Epub 2024 Dec 19. PMID: 39697103; PMCID: PMC12008612.
[5] Slominski A, Wortsman J, Plonka PM, Schallreuter KU, Paus R, Tobin DJ. Hair follicle pigmentation. J Invest Dermatol. 2005 Jan;124(1):13-21. doi: 10.1111/j.0022-202X.2004.23528.x. PMID: 15654948; PMCID: PMC1201498.
[6] Maghfour J, Ozog DM, Mineroff J, Jagdeo J, Kohli I, Lim HW. Photobiomodulation CME part I: Overview and mechanism of action. J Am Acad Dermatol. 2024 Nov;91(5):793-802. doi: 10.1016/j.jaad.2023.10.073. Epub 2024 Feb 1. PMID: 38309304.
[7] American Academy of Dermatology. Is red light therapy right for your skin? [Internet]. Rosemont (IL): American Academy of Dermatology; 2024 Sep 13 [cited 2026 Sep 2]. Available from: https://www.aad.org/public/cosmetic/safety/red-light-therapy
