In the near future, dozens of chronic diseases might be treated effectively with near-infrared and visible red light. There is little talk, yet a lot of research on this subject.
The mitochondrial enzyme cytochrome c oxidase is activated by certain wavelengths of electromagnetic radiation. The most important wavelengths are 600-850nm, the visible red light and the short-wavelength infrared radiation. The latter of these penetrates much deeper into tissue, affecting the organism more deeply.
The activation of cytochrome c oxidase increases the cellular energy metabolism significantly leading to higher ATP production[4-6], and also decreases pro-inflammatory cytokines (TNF-alfa, IL-6) in the circulation dramatically.[7-8]
In human studies, near-infrared has been very useful for eg. achilles tendonitis, fibromyalgia, labial herpes, male pattern hair loss, oral mucositis, hypothyroidism, lymphedema, knee osteoarthritis, age-related macular degeneration and lateral epicondylitis. Visible red light has also been useful for body contouring.[9-19]
The results have often been dramatic even in the placebo-controlled studies. In one study, almost all of the elderly patients saw improvements of their vision after near-infrared therapy. In another study, patients with knee osteoarthritis saw dramatic decreases in the pain levels after a few weeks of near-infrared therapy. In a third study, nearly half (47%) of the hypothyroid patients could eliminate their thyroxine medication after the near-infrared treatment period.
Most of the studies have been conducted with low level laser devices (LLLT), and a smaller part have been done with LED lamps or halogen lamps. But despite the fact that laser has been used in most of the studies, the term “laser” only indicates that the light is coherent, and the research has already shown that the coherence (or polarization) of the light is not a requirement for the biological effectiveness of the near-infrared light.[20-21]
Thus, it is completely possible that similar benefits could be achieved with non-laser light sources such as sunlight*, heat lamps or incandescent bulbs. Actually, more than 100 years ago John Harvey Kellogg published a book Light Therapeutics (1910) in which he reported great health benefits from his incandescent bulb therapy.
The majority of infrared saunas do not emit near-infrared radiation so their possible benefits are not related to the activation of cytochrome c oxidase.
*Sunlight also contains ultraviolet radiation and blue light, both of which have opposite effects to near-infrared light. Thus, it might be wise to get sunlight through a window (glass blocks most of UV radiation).
 A much longer article on this topic, with more than 100 scientific references, has also been published.
 Tiina I. Karu: Multiple Roles of Cytochrome c Oxidase in Mammalian Cells Under Action of Red and IR-A Radiation (2010, pdf)
 Jagdeo et al: Transcranial red and near infrared light transmission in a cadaveric model. (2012)
 Karu et al: Irradiation with He-Ne laser increases ATP level in cells cultivated in vitro. (1995)
 Benedicenti et al: Intracellular ATP level increases in lymphocytes irradiated with infrared laser light of wavelength 904 nm. (2008)
 Lapchatk et al: Transcranial near infrared laser treatment (NILT) increases cortical adenosine-5'-triphosphate (ATP) content following embolic strokes in rabbits. (2010)
 Zhevago&Samoilova: Pro- and Anti-inflammatory Cytokine Content in Human Peripheral Blood after Its Transcutaneous (in Vivo) and Direct (in Vitro) Irradiation with Polychromatic Visible and Infrared Light (2006)
 Byrnes et al: Light promotes regeneration and functional recovery and alters the immune response after spinal cord injury. (2005)
 Bjordal et al: A randomised, placebo controlled trial of low level laser therapy for activated Achilles tendinitis with microdialysis measurement of peritendinous prostaglandin E2 concentrations. (2006)
 Gür et al: Effects of low power laser and low dose amitriptyline therapy on clinical symptoms and quality of life in fibromyalgia: a single-blind, placebo-controlled trial. (2002)
 Schindl&Neumann: Low-intensity laser therapy is an effective treatment for recurrent herpes simplex infection. Results from a randomized double-blind placebo-controlled study. (1999)
 Leavitt et al: HairMax LaserComb laser phototherapy device in the treatment of male androgenetic alopecia: A randomized, double-blind, sham device-controlled, multicentre trial. (2009)
 Antunes et al: Phase III trial of low-level laser therapy to prevent oral mucositis in head and neck cancer patients treated with concurrent chemoradiation. (2013)
 Höfling et al: Low-level laser therapy in chronic autoimmune thyroiditis: a pilot study. (2010)
 Ahmed Omar et al: Treatment of post-mastectomy lymphedema with laser therapy: double blind placebo control randomized study. (2011)
 Hegedus et al: The effect of low-level laser in knee osteoarthritis: a double-blind, randomized, placebo-controlled trial. (2009)
 Ivandic&Ivandic: Low-level laser therapy improves vision in patients with age-related macular degeneration. (2008)
 Lam&Cheing: Effects of 904-nm low-level laser therapy in the management of lateral epicondylitis: a randomized controlled trial. (2007)
 Jackson et al: Low-level laser therapy as a non-invasive approach for body contouring: a randomized, controlled study. (2009)
 Chung et al: The Nuts and Bolts of Low-level Laser (Light) Therapy (2012)
 Barulin&Plavskii: Effect of Polarization and Coherence of Optical Radiation on Sturgeon Sperm Motility (2012)