lighttherapy

Light therapy, also called phototherapy, is the use of controlled exposure to bright light for therapeutic purposes. It commonly employs devices such as light boxes, light visors, or ceiling-mounted luminaires that deliver specific wavelengths and intensities of visible light, with sessions usually ranging from a few minutes to an hour daily. Treatments are typically guided by medical advice or device instructions.

The therapeutic effects arise through different mechanisms. For circadian rhythm disorders and seasonal affective disorder, light exposure influences the retinal cells that contain melanopsin, signaling the brain’s body clock and helping regulate sleep timing and melatonin production. For skin conditions and wound healing, phototherapy uses photobiomodulation: light interacts with cellular chromophores to modulate inflammation, metabolism, and collagen production. Near-infrared or red wavelengths are commonly used in dermatology and rehabilitation.

Common indications include seasonal affective disorder and other depressive disorders, circadian rhythm sleep disorders, jet lag, and certain skin conditions such as acne, psoriasis, and eczema. Neonatal jaundice has historically been treated with blue light to reduce bilirubin levels. Light therapy is also explored for wound healing and mucositis, though evidence varies by condition and treatment protocol.

Safety and guidance are important. Eye protection during treatment is recommended, and some individuals may experience eyestrain, headaches, or skin irritation. Excessive exposure or high irradiance can increase the risk of burns. Efficacy varies by condition and study quality, so professional guidance and regulatory compliance are important. People with bipolar disorder, glaucoma, or retinal disease should consult a clinician before use.

Historically, the use of bright light for mood disorders gained prominence in the late 20th century, with robust evidence emerging in the 1980s and 1990s. Since then, research has broadened to dermatology, circadian medicine, and rehabilitation, with ongoing work to refine wavelengths, timing, and dosing.