History and Fundamentals of Low-Level Laser (Light) Therapy

The use of laser or other light sources for reducing pain and inflammation, augmenting tissue repair and regeneration, healing deeper tissues and nerves, and preventing tissue damage (among other medical applications) is known as low-level laser (or light) therapy (LLLT), phototherapy, or photobiomodulation. Over many centuries, light therapy has been one of the oldest therapeutic modalities used to treat various health conditions (Daniell and Hill 1991). Ancient Egyptian, Indian, and Chinese civilizations used sunlight or heliotherapy to treat various diseases, including psoriasis, rickets, vitiligo, and skin cancer. Modern phototherapy was later rediscovered by Niels Ryberg Finsen, a Danish physician and scientist who won the 1903 Nobel Prize in physiology or medicine in recognition of his contribution to the treatment of diseases, notably lupus vulgaris. Finsen developed a “chemical rays” lamp with which he treated many patients with skin tuberculosis. He also found that redlight exposure prevents the formation and discharge of smallpox pustules and can be used to treat this disease. This was the beginning of modern phototherapy using an artificial irradiation source (Honigsmann 2013; Roelandts 2005).