There are two new studies showing the positive effect of laser therapy on the growth of scalp hair. Here is another good study that evaluated the effect of red laser on the growth of human hair in a double-blinded study. Lanzafame et al authored the study. This study uses a placebo group that uses incandescent red light instead of laser lights.
The study is nicely designed to compare the effect of laser on the growth of the hair follicles by enrolling 44 men between the ages of 18 and 48. The subjects have hair loss classes of IIA to V.
The investigators trimmed hair in the balding area to 3 mm height and used tattoo to mark for future evaluation. They noticed significant improvement in the laser group as opposed to the placebo one resulting in a 35% percent increase in hair growth (32.3 ± 44.2). The authors concluded that LLLT at 655 nm can significantly improve hair counts in males with androgenetic alopecia. This article was published in the Journal of Lasers in Surgery and Medicine.