Topical Melatonin for Hair: The Science Beyond Sleep

Melatonin in a hair serum is not there for sleep. Hair follicles make their own melatonin and carry receptors that sense it, a local system separate from the brain's sleep signal. In lab and mouse work that system rises and falls with the hair cycle, and in mice extra melatonin promoted regrowth. Topical studies tested a melatonin solution used once a day for three to six months on people with hair loss. The two studies that measured blood melatonin found it stayed in the body's normal nighttime range in one and was not significantly changed in the other.

Make: your follicles have their own melatonin

Melatonin is best known as the hormone the pineal gland, a small gland in the brain, releases at night to signal darkness. The pineal is not the only place that makes it.

A 2005 study in The FASEB Journal, led by Kobayashi and colleagues, looked for melatonin inside hair follicles.

What was tested: mouse skin, mouse whisker follicles and human scalp follicles, all kept alive in the lab. The team measured melatonin directly with two lab methods (a radioimmunoassay and mass spectrometry).

What they found: the melatonin concentration in the cultured skin and follicles was far above the level in blood serum, and it rose when the cultures were given norepinephrine, the same chemical signal that switches on melatonin production in the pineal gland. A later review (Fischer and colleagues, Journal of Pineal Research, 2008) adds that human scalp follicles in the growing phase make melatonin.

That is a lab model, not a person on a bathroom shelf. It shows that the machinery for making melatonin sits in the follicle itself.

Sense: what the receivers do in the hair cycle

A follicle that makes melatonin needs something to sense it. First, the hair cycle in one paragraph. Each follicle moves through anagen (the growing phase), catagen (a short regression phase when the lower follicle shrinks) and telogen (the resting phase), then starts again.

Kobayashi's team measured the gene readouts for two melatonin receivers in mouse back skin: MT2, a receptor on the cell surface, and RORα, a receptor that works inside the cell nucleus. Both rose and fell with the hair cycle and peaked in catagen. The paper also reports that melatonin lowers apoptosis (programmed cell death) in the skin cells that build the hair and lowers the amount of estrogen receptor alpha, the docking site for estrogen. The 2008 review describes the full detail of how melatonin steers the cycle as not completely worked out, and notes that melatonin also acts as a free-radical scavenger.

A 2024 mouse study in Cell Proliferation (Niu and colleagues) went after the signal.

What was tested: mice with hair removed to trigger regrowth, given either melatonin or luzindole, a drug that blocks melatonin receptors. Then a cell-culture setup that paired dermal papilla cells (the cluster at the base of the follicle that directs growth) with hair follicle stem cells.

What they found: melatonin significantly promoted regrowth, and luzindole significantly suppressed it. Gene analysis pointed to the Wnt/β-catenin pathway, a signaling route that tells follicle cells to grow. In the co-culture, melatonin switched the pathway on in the dermal papilla cells when stem cells were present. On dermal papilla cells alone, it did not. Think of it as melatonin talking to the stem cells, and the stem cells passing the message to the papilla.

That is mouse work and cell culture, not a human trial. It gives the topical studies below a reason to exist.

Supply: what the topical studies applied

If the follicle already makes and senses melatonin, the next question is what happens when you supply more at the scalp. These are the human studies we retrieved, sorted by design.

Three terms in the table: androgenetic alopecia is the common pattern type of hair loss, TrichoScan is a digital photo method that counts hairs per square centimeter, and a hair pull test counts how many hairs come out when a small bundle is gently pulled.

Swipe to see all five columns →

The placebo-controlled trial. Fischer and colleagues (British Journal of Dermatology, 2004) randomized 40 women to 0.1% melatonin solution or a placebo solution, applied to the scalp once a day for six months. The women had either androgenetic alopecia (the common pattern type, 12 women) or diffuse hair loss (28 women). The team used a trichogram: a small sample of hairs is taken from a chosen site and examined under a microscope to count how many are in the growing phase. They checked a site at the back of the head (occipital) and a site at the front (frontal).

The share of growing hairs rose significantly versus placebo in the back-of-head hair of the androgenetic group and in the front hair of the diffuse group. Other site and group combinations rose without reaching significance. The authors suggest melatonin may induce the growing phase and say the mode of action was not established.

The men. The same lead author reported five studies together in the International Journal of Trichology (2012). One of the five was a pharmacodynamic study that measured blood melatonin (see the sleep section below). In another, 35 men with androgenetic alopecia were followed with TrichoScan. Hair density rose from 123 to 159 hairs per cm² at three months and to 173 at six months, with a significant increase in 54.8% to 58.1% of the men. These were before-and-after studies without a placebo group. In a separate 60-person study, hair loss fell in women and stayed constant in men. In the 1,800-volunteer study, volunteers used the solution for three months and the share with a clearly positive hair pull test fell from 61.6% to 7.8%.

The wider picture. A 2023 review in the Journal of Drugs in Dermatology (Babadjouni and colleagues) collected 11 human studies of melatonin in people with diagnosed alopecia, covering 2,267 patients. Eight studies reported positive outcomes with topical melatonin in androgenetic alopecia. The review reports that the topical solutions that appeared effective were 0.0033% or 0.1%, applied once a day for 90 to 180 days.

Sleep: does scalp melatonin reach the blood?

Does melatonin on the scalp make you sleepy? The study summaries we reviewed do not report sleepiness. They report blood melatonin, which is the measurable version of the question.

• In the 2004 trial, plasma melatonin was measured in the women using the 0.1% solution. It rose, and it stayed within the range of the body's normal nighttime peak.
• In the 2012 pharmacodynamic study, a solution applied once a day in the evening did not significantly change endogenous serum melatonin.

In these studies the solution went on the scalp once a day, and blood melatonin stayed in or near its normal range.

What "growing phase support" means in practice

In these studies the growing phase is a countable thing: the share of hairs in anagen on a trichogram, or density on TrichoScan. It is also slow. The placebo-controlled trial ran six months, the men's TrichoScan study three and six months, and the multicenter study three months. A hair that enters anagen still has to grow long enough to be seen.

If you try any growing-phase ingredient, give it months and track it with the same photos in the same light. Our progress photos guide shows how.

Melatonin in Loxstar

Loxstar Peptide Hair Growth Serum lists Melatonin on its ingredient list. Through the lens of this article, it is the supply part: melatonin placed at the scalp for a follicle that already makes and senses it. It sits alongside the formula's core, the RCP blends of Redensyl, Capixyl and Procapil explained in our RCP guide, plus AnaGain, liposomal caffeine and supporting botanicals. For every ingredient and its role, see the Loxstar formula map.

The directions are the same for the whole formula: once a day on a clean scalp after showering, a pea-size amount on thinning areas, 30 seconds of massage, then about five minutes before styling.