Does Melatonin Talk to Hair Follicle Stem Cells?

Most of us know melatonin as the hormone that helps regulate sleep. As daylight fades, melatonin levels rise, helping to prepare the body for night.

Yet hair follicles also produce melatonin.

They do this regardless of whether we are asleep or awake, suggesting that within the follicle, melatonin serves a different purpose.

The obvious question is why.

For many years, researchers have assumed that melatonin helps protect the hair follicle. Hair follicles are remarkably active structures. They are constantly growing, dividing and producing new tissue, all of which generates metabolic stress. Melatonin is a powerful antioxidant, so it makes sense that it may help protect the follicle from this everyday wear and tear.

But perhaps that’s not the whole story.

A study published in 2026 explored another possibility. Rather than simply protecting the hair follicle, could melatonin also influence the cells responsible for producing each new hair?

The Hair Follicle Stem Cells

Every new hair begins with a small population of stem cells.

These cells live within a specialised part of the follicle called the bulge. Unlike many of the cells that actively produce the hair shaft, stem cells spend much of their time relatively inactive. They remain in reserve until a new hair cycle begins.

When the time is right, these stem cells divide and produce the cells needed to build an entirely new hair.

Without them, there can be no new hair growth.

Exactly what tells these stem cells that the time is right remains one of the fascinating questions in hair biology.

They do not act independently. Instead, they respond to signals from the cells around them. Some signals encourage growth, while others suppress it. The follicle is less like a machine with an on-off switch and more like a conversation involving many different participants.

The possibility that melatonin is one of those participants is an intriguing one.

What Did the Researchers Find?

The researchers did not study patients with hair loss. Instead, they examined human hair follicle stem cells grown in the laboratory.

When these stem cells were exposed to melatonin, they divided more readily and migrated more effectively. Importantly, they also retained the characteristics expected of healthy stem cells.

The researchers also observed reduced expression of 5-alpha reductase, the enzyme responsible for converting testosterone into dihydrotestosterone (DHT), alongside increased expression of the melatonin receptor known as MT1.

Taken together, these findings suggest that melatonin may influence hair follicle stem cells in several different ways, including pathways linked to androgenetic alopecia.

What Does This Mean?

It is tempting to jump straight to the question many people will ask.

Does this mean melatonin treats hair loss?

The answer is not on the basis of this study.

This was laboratory research, not a clinical trial.

The investigators demonstrated what melatonin can do under carefully controlled experimental conditions. Whether the same effects occur within the scalp of someone with androgenetic alopecia is a different question entirely.

Nevertheless, studies like this are valuable because they help us understand how hair follicles work.

For many years, much of the focus in androgenetic alopecia has been on DHT and the dermal papilla.

Increasingly, however, researchers are turning their attention to the follicle’s stem cells and the signals that regulate their behaviour.

Melatonin may prove to be one of those signals.

Final Thoughts

Hair follicles continue to surprise us.

Once thought of simply as tiny factories producing hair, they are now recognised as complex miniature organs whose behaviour depends on countless conversations between stem cells, immune cells, hormones, growth factors and their surrounding environment.

This study does not show that melatonin is a treatment for androgenetic alopecia. However, it does add another piece to the puzzle. By suggesting that melatonin may influence the behaviour of hair follicle stem cells, it raises new questions about how hair growth is regulated and why hair follicles produce their own melatonin in the first place.

Whether melatonin proves to be an important voice in that conversation, or merely one of many, remains to be discovered.

As is so often the case in science, answering one question has led to many more.

Reference

Zhang X, Li Y, Wang J, et al. Melatonin promotes proliferation, migration and stemness of human hair follicle stem cells by regulating SRD5A2 expression. Journal of Cosmetic Dermatology. 2026.

About the Author

Dr Gwen Adey BDS MFDS RCS Ed is a dental surgeon with a background in clinical research and a special interest in regenerative medicine and hair restoration. Through the Hair Biology Essays series, she explores the science behind hair growth and hair loss, translating emerging research into balanced, evidence-based articles for patients.

These essays are intended for educational purposes and should not be considered individual medical advice. Treatment decisions should always be made in consultation with an appropriately qualified healthcare professional.