Tip Chapter: Low-Level Light Therapy and High-Energy Lasers in Trichology

The mechanism of light therapy is called phototherapy [3, 4]. It requires absorption of a specific wavelength by a light-absorbing molecule (chromophore), which can be produced and synthesized endogenously or applied exogenously to the receptor in cell tissues [3, 9, 12]. Irradiation in the photoreceptor generates a cascade of responses from the cells that leads to modulation of the cell function, proliferation, and repair of damaged cells [3, 9, 12]. The term that describes this “potentiation/cell function modulation” process is called photobiomodulation [3, 4, 9, 12] (Figs.109.1, 109.2, 109.3, and 109.4).