Melatonin: Does It Work the Same for Men and Women?

Melatonin is a hormone produced by the pineal gland in the brain, fundamental in regulating sleep-wake cycles. Its release increases in darkness, facilitating sleep, and decreases with light, promoting wakefulness.

However, in recent years, melatonin has gained interest in another area: hair health.

Research is exploring its potential to treat different types of alopecia, but does this hormone function identically in men and women? No trial has been designed to answer that question directly. What can be examined is the reported sex difference in melatonin secretion, the types of alopecia, and what the small hair studies actually measured in each sex.

Types of Alopecia and Its Relationship with Melatonin

Alopecia refers to abnormal hair loss and can have multiple causes. Some types affect both genders equally, while others are specific to men or women.

Understanding these types is crucial to assessing melatonin's potential as a treatment.

• Androgenetic Alopecia: This is the most common form, influenced by the hormone dihydrotestosterone (DHT). It affects both men and women, although with different patterns: in men, it manifests as a receding hairline and crown thinning, whereas in women, it causes diffuse thinning. This type of alopecia has a strong genetic and hormonal component.

• Alopecia Areata: An autoimmune disease that can occur in anyone, regardless of gender. It is characterized by sudden hair loss in patches and may be linked to factors such as stress or family history.

• Diffuse Alopecia or Telogen Effluvium: This condition is associated with stress, hormonal changes, nutritional deficiencies, and underlying illnesses. It can affect both men and women, though hormonal fluctuations in women (such as during pregnancy or menopause) may make them more susceptible.

• Frontal Fibrosing Alopecia: This condition is observed almost exclusively in postmenopausal women and is believed to be linked to hormonal and environmental factors. It causes a receding hairline in the frontal area and can be challenging to treat.

• Hair Loss Linked to Nutritional Deficiency: Shortages of iron, zinc or vitamin D are described in the dermatology literature as contributors to hair shedding, and clinicians treat a confirmed deficiency on its own merits. Correcting a deficiency does not reverse hair loss that has another cause, and dietary biotin deficiency severe enough to cause hair loss is rare. A blood test ordered by a doctor is what distinguishes these cases; supplementing without one does not.

Melatonin: From Sleep to Hair Growth

It is not uncommon for a drug developed for one purpose to end up being used for something entirely different.

Examples include finasteride, initially intended to treat benign prostatic hyperplasia but later recognized as a key treatment for androgenetic alopecia. Similarly, minoxidil was created as an antihypertensive medication and ended up becoming a popular treatment for hair loss. (See more information in previous articles.)

There is also a documented sex difference in melatonin itself. Duffy and colleagues (PNAS, 2011) reported that the intrinsic period of the human circadian clock is shorter on average in women than in men, and Obayashi and colleagues (Journal of Epidemiology, 2015) measured overnight urinary melatonin output in 528 older adults and found it about 18% lower in women than in men, independent of light exposure. These are studies of sleep physiology, not of hair, so they establish that melatonin behaves somewhat differently by sex — not that it acts differently on the follicle.

Traditionally used to regulate sleep, melatonin has sparked interest in dermatology. Preliminary studies suggest that it may affect hair by reducing oxidative stress and prolonging the hair growth phase; this is a proposed mechanism, not a demonstrated one.

The most directly relevant human study is a pilot randomized controlled trial by Fischer and colleagues (British Journal of Dermatology, 2004). Forty women — the trial enrolled women only — with androgenetic or diffuse alopecia applied a 0.1% melatonin solution or placebo to the scalp once daily for six months, assessed by trichogram. Melatonin significantly increased the anagen (growth-phase) hair rate in occipital hair in the androgenetic subgroup (n = 12; P = 0.012) and in frontal hair in the diffuse-alopecia subgroup (n = 28; P = 0.046); the other two comparisons were not significant. Because no men took part, this trial says nothing about whether the effect differs by sex.

The one published hint of a sex difference comes from a 2012 paper by Fischer and colleagues in the International Journal of Trichology, which summarises one pharmacodynamic study and four clinical studies of a cosmetic topical melatonin solution. In one of those studies, in 60 men and women with hair loss, a significant reduction in hair loss was reported in the women, while hair loss in the men remained constant. That is a single, uncontrolled observation. Four of the five studies in that paper had no placebo arm, so improvement over time cannot be separated from the natural course of the condition, and the review does not analyse hormonal mechanisms or test men and women against each other.

Taken together, the published work is too small and too rarely sex-stratified to support a claim that melatonin works better, or worse, in either sex.

Melatonin-Based Hair Products on the Market

Melatonin appears in a small number of scalp tonics, serums and shampoos, usually combined with ingredients such as rosemary extract, biotin or ceramides. These are cosmetic products in most markets: the formulation is not assessed by a medicines regulator for hair-loss efficacy, the melatonin concentration is frequently not stated on the pack, and none of these specific combinations has been tested in a published trial. Manufacturer copy about reducing oxidative stress on the scalp is marketing language, not a clinical finding, and no product on sale has been shown to reproduce the results of the studies above.

User Experiences

Community feedback on melatonin's effect on hair loss varies, with users reporting differing results based on gender and individual response. Some male users have noted positive effects, particularly in reducing hair shedding and improving hair density when applying melatonin topically. They report that melatonin's antioxidant and anti-inflammatory properties may play a role in counteracting hair follicle miniaturization. Additionally, some men claim that combining melatonin with treatments like minoxidil or microneedling enhances their results.

For female users, experiences appear more mixed. Some women state that melatonin helps regulate their hair cycles, potentially reducing excessive shedding linked to hormonal imbalances. However, a few female users express concerns about systemic hormonal effects, particularly regarding changes in their menstrual cycle or sleep patterns. Some report increased hair thickness after prolonged use, while others do not notice significant improvements. There are also cases where users, both male and female, mention initial shedding phases when starting melatonin, similar to other hair growth treatments.

One recurring discussion among community members involves whether oral or topical melatonin is more effective. Many believe that topical application directly stimulates hair follicles without affecting systemic hormone levels, while oral melatonin might be more beneficial for individuals with stress-related hair loss. Some users suggest combining melatonin with other treatments, like ketoconazole or finasteride. These are individual accounts, not trial results, and finasteride in particular is a prescription medicine that is contraindicated in women who are or may become pregnant.

Overall, while some community members find melatonin beneficial, responses vary significantly between individuals and genders. Many suggest further research is needed to understand its full potential and mechanisms.

Final Considerations

Melatonin plays a role in regulating sleep in both sexes, and measured melatonin output does differ between men and women. Its impact on hair health remains an emerging field of study: the only placebo-controlled scalp trial enrolled women only, and the single reported sex difference in hair outcomes comes from an uncontrolled observation in 60 people. More research is needed before anyone can say whether melatonin's effects on hair differ by sex.

Melatonin is a hormone, and in several countries it is a prescription medicine rather than a supplement. Talk to a doctor or pharmacist before starting, stopping or combining melatonin — taken orally or applied to the scalp — especially if you are pregnant, breastfeeding, planning a pregnancy, or already taking other medicines.

References

Duffy, J. F., Cain, S. W., Chang, A.-M., Phillips, A. J. K., Münch, M. Y., Gronfier, C., & Czeisler, C. A. (2011). Sex difference in the near-24-hour intrinsic period of the human circadian timing system. Proceedings of the National Academy of Sciences, 108(Suppl. 3), 15602–15608. https://pubmed.ncbi.nlm.nih.gov/21536890/

Obayashi, K., Saeki, K., Iwamoto, J., Ikada, Y., Kurumatani, N., & Tomioka, K. (2015). Lower melatonin secretion in older females: gender differences independent of light exposure profiles. Journal of Epidemiology, 25(1), 38–43. https://pubmed.ncbi.nlm.nih.gov/25223887/

Fischer, T. W., Burmeister, G., Schmidt, H. W., & Elsner, P. (2004). Melatonin increases anagen hair rate in women with androgenetic alopecia or diffuse alopecia: results of a pilot randomized controlled trial. British Journal of Dermatology, 150(2), 341–345. https://pubmed.ncbi.nlm.nih.gov/14996107/

Fischer, T. W., Trüeb, R. M., Hänggi, G., Innocenti, M., & Elsner, P. (2012). Topical melatonin for treatment of androgenetic alopecia. International Journal of Trichology, 4(4), 236–245. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681103/