Evidence that low-level laser therapy (LLLT) could be used to promote hair growth, possibly by stimulating cellular function which leads to cell proliferation, a process called photobiomodulation, was first presented by Endre Mester, a Hungarian physician, in 1967. ((Mester E, Szende B, Tota JG. Effect of laser on hair growth in mice. Kiserl Orvostud 1967;19:628–631.))
Since then, many studies investigating the effects of LLLT on patients with pattern baldness (androgenic alopecia) have found a positive therapeutic effect, but most of those studies have not been properly controlled so as to rule out other, alternative, explanations for any observed hair growth.
However, a recent study ((Lanzafame R, Blanche R, Bodian A, Chiacchierini R, Fernandez-Obregon A, Kazmirek E. The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers in Surgery and Medicine 2013; Vol. 45, Issue 8: 487-95.)) published in the journal of Lasers in Surgery and Medicine tested both the safety and effectiveness of a LLLT device in a randomized, blinded, controlled study and found that low-level laser light in the 655nm range significantly promoted hair growth in male patients with androgenic alopecia.
Specifically, 20 male subjects with pattern baldness were treated with low-level laser light for 25 minutes per day every other day for 16 weeks. After 16 weeks, a 35% increase in hair growth was observed in these subjects compared to an untreated group of males with pattern balding.
The researchers suggest that LLLT may stimulate the mitochondria in the cells of the hair follicle, leading to an increase in biological activity in those cells that promote hair growth. They also suggest that low-level light in the range used in the study might affect a hair follicle’s stem cells, which may also contribute to hair growth.