Melatonin is a hormone primarily recognized for regulating the body’s sleep-wake cycle, or circadian rhythm. It is naturally produced by the pineal gland in the brain in response to darkness, signaling the body that it is time to rest. Scientific interest has expanded beyond its sleep functions to investigate its potential dermatological benefits. Specifically, researchers are examining whether this hormone can be repurposed as a therapeutic agent for hair loss, a condition known as alopecia. Focused studies are investigating its application as a non-invasive treatment to stimulate hair growth.
Melatonin’s Role in the Hair Growth Cycle
Hair growth cycles through three distinct phases: the active growth anagen phase, the brief transition catagen phase, and the resting telogen phase, where hair is eventually shed. Melatonin has been found to be synthesized not only in the brain but also in peripheral tissues, including the scalp’s hair follicles, suggesting a localized regulatory role.
The hormone acts as a powerful antioxidant and anti-inflammatory agent directly within the hair follicle structure. This is significant because oxidative stress and inflammation are major factors that can prematurely push the hair follicle from the active anagen phase into the shedding telogen phase. By scavenging damaging free radicals, melatonin helps protect the follicular cells from environmental stress.
Melatonin is theorized to prolong the anagen phase, keeping hair in a state of active growth for a longer duration. It achieves this by interacting with specific melatonin receptors (MT1 and MT2) found on hair follicle cells. This interaction modulates signaling pathways, such as the WNT/\(\beta\)-catenin pathway, which is instrumental in the proliferation and differentiation of hair follicle stem cells.
Clinical Findings on Melatonin and Hair Density
The core question for individuals experiencing hair thinning is whether laboratory findings translate into measurable results on the scalp. Clinical studies have predominantly focused on topical melatonin solutions for common forms of hair loss, such as androgenetic alopecia and telogen effluvium. Evidence suggests that applying melatonin directly to the scalp yields quantifiable improvements in hair growth parameters.
One study investigating topical melatonin’s effect on men with androgenetic alopecia showed a significant increase in hair count. Over six months, participants experienced a measured increase in hair count of up to 42.7%, with a corresponding hair density increase of approximately 40.9%. These results were determined using objective, digital measurement techniques.
Another large-scale, multicenter study involving over 1,800 patients demonstrated melatonin’s efficacy in reducing hair shedding. After 90 days of topical application, the percentage of participants with a positive hair-pull test, an indicator of active hair loss, decreased from over 61% to less than 8%. The proportion of patients who showed no hair loss increased substantially, indicating a significant reduction in shedding.
Clinical data strongly supports topical application rather than oral supplementation for this purpose. A pharmacokinetic study confirmed that topical application does not significantly influence systemic melatonin levels, avoiding interference with the natural sleep cycle. While studies show promising results, they often involve smaller patient groups, underscoring the need for larger, placebo-controlled trials.
Guidelines for Topical Application
Individuals considering a melatonin solution must adhere to a consistent application regimen for achieving results. Topical formulations are typically available in specific concentrations based on clinical trials. An effective concentration range for the solution is often cited as 0.0033% to 0.1%.
Application is generally recommended once daily, with most studies suggesting an evening application. This timing aligns with the natural circadian rhythm and the hormone’s known activity patterns. Since the hair growth cycle is slow, noticeable improvement requires patience, with results typically appearing after three to six months of consistent application.
Melatonin is well-tolerated when applied to the scalp, and systemic side effects are minimal because topical application does not significantly elevate blood melatonin levels. Some users report mild, temporary side effects at the application site, such as skin reddening, sensitivity, itching, or a burning sensation. Consulting with a dermatologist is advisable before beginning any new treatment to confirm the diagnosis and ensure the treatment is appropriate.