Chandra's Skin Care Low-Level Laser Light is one of the most effective therapies to treat hair loss. The laser energy used to stimulate hair growth is visible in the red light spectrum. The laser light used in promoting hair growth is defined as Low-Level Laser Therapy (LLLT). LLLT is sometimes included under a broader definition of ‘Phototherapy’ called Low-Level Light Therapy, where the light-emitting device may be a laser and/or light-emitting diode (LED)