A 2013 study in Biomedical Research examined the effect of light therapy on testosterone production in lab rats. The study found that light therapy applied for 5 days, 30 minutes a day at 670 nanometers significantly increased serum testosterone levels.

Human trials in 2016 conduced by the University of Siena evaluated men with lowe sexual desire. The study found that using light therapy generated a testosterone increase that resulted in better sexual satisfaction.

Low-level laser therapy — also referred to as red light therapy and cold laser therapy — irradiates photons into scalp tissues. These photons are absorbed by weak cells to encourage hair growth. It's widely accepted that the procedure is safe, tolerable, and less invasive than hair transplant surgery.