Melatonin is a hormone produced in the brain, and is most well known for its role in the sleep-wake cycle. Supplements of this hormone are typically used by people affected by insomnia, jet lag and sleep problems related to shift work.
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Topical application of this hormone is also being studied for an unrelated purpose — to treat hair loss. While more research is needed, preliminary data suggests melatonin may be beneficial to hair growth.
The Hair Growth Cycle
Hair growth occurs in the hair follicles, in a cycle comprised of 3 phases. In a healthy, hairy scalp, most hair follicles are in the anagen, or active phase of hair growth. Hair strands in this phase won't normally fall out, and the more time hair stays in this phase, the longer and faster it will grow.
This anagen phase can last for several years, after which hair growth stops, and the hair follicle moves into a brief transitional, or catagen phase. Next, the hair moves into a short resting, or telogen phase. At this time, the hair shaft falls out and a new hair starts growing in the follicle.
The Melatonin Connection
Hair growth is regulated by hormones, called androgens, and increased activity of these hormones can shorten the anagen phase of hair growth and result in male or female-pattern baldness.
This is where melatonin comes in. Hair follicles have melatonin receptors, and through chemical interactions, melanin may oppose the action of androgens — lengthening the anagen phase, increasing hair production and preventing hair loss.
Melatonin is also a powerful antioxidant, and is theorized to protect the scalp and hair follicle from the inflammation and tissue damage that contributes to hair loss. In addition, melatonin benefits cell growth, and may counter the damage of environmental stressors that impact the skin and hair, such as chemical and sun damage.
What the Research Says
The study most frequently cited in support of melatonin as a hair growth treatment was published in the February 2004 issue of "British Journal of Dermatology." This small study asked 40 women with hair loss to apply a 0.1 percent melatonin or placebo solution to their scalp once daily for six months.
By the end of the study period, the women who used the melatonin solution had a higher percentage of scalp hair in the anagen or active growth phase, compared to women using placebo. While these results are promising, additional research is needed to confirm these findings, and to ensure larger studies also find the melatonin effective.
Of note, researchers in this study reported an increase in blood melatonin levels in women who used the melatonin solution on their scalp, but the levels were not higher than usually produced by the body. This underscores the importance of research to determine safe topical use.
The vast majority of melatonin products on the market are designed for oral use, and these supplements have not been studied for treatment of hair loss. When taken orally, melatonin can produce side effects, including dizziness, headache, drowsiness or nausea.
According to the National Institutes of Health, melatonin has not been tested in pregnant or lactating women or children. Before using any supplement, talk with your doctor, especially if you have any medical conditions or take prescription medication. For professional treatment of hair loss, and to understand the safety and effectiveness of hair loss remedies, consult a dermatologist.
Reviewed by Kay Peck, MPH RD