Hormonal influences of testosterone and dihydrotestosterone (DHT) on human hair growth have been extensively researched. Various studies with the Kashmir goat or the New Zealand goat have shown that the hormone melatonin, which also occurs in the human organism, regulates the seasonal hair growth cycle and is involved, for example, in triggering the anagen phase of hair growth. Further in vitro studies also showed positive influences of melatonin on hair growth. The motivation of the underlying pilot study is to investigate the effect of the hormone melatonin on the human hair growth cycle. The double-blind, randomized and placebo-controlled study included 40 participants suffering from androgenetic or diffuse hair loss.
In order to clarify the extent to which topically applied melatonin influences the anagen and telogen hair growth rate in women with androgenetic or diffuse hair loss, a 0.1% melatonin solution (or placebo solution for participants in the control group) was applied daily to the scalp of the test participants over a period of 6 months. Trichograms were performed to determine the anagen and telogen hair growth rate. Blood samples were taken throughout the study to monitor melatonin levels.
Diagram 1: Trichogram of the occiput, figures in percent
Diagram 2: Trichogram of the forehead, figures in percent
Compared to the placebo control group, the use of melatonin led to a significantly increased rate of anagen hair at the back of the head of the study participants with androgenetic alopecia. In study participants with diffuse hair loss, melatonin caused a significant increase in frontal hair. Hair samples from the back of the head of study participants with diffuse alopecia and the counts of the frontal hair also showed an increase in anagen hair, but without significant differences to the control group. The melatonin levels in the blood plasma increased over the period of application, but never above the physiological peak value, which is typically present at night.
Conclusion
The results of the underlying study suggest that the mechanism of action of melatonin is the initiation of the early anagen phase. Melatonin proved to be clearly hair growth-promoting in the study.
Underlying study:
Fischer, T. W. et al: Melatonin increases anagen hair rate in women with androgenetic alopecia or diffuse alopecia: results of a pilot randomized controlled trial; in: British Journal of Dermatology, February 2004, 150(2): 341-345.