Light therapy, also called phototherapy or bright light therapy is the exposure to direct sunlight or artificial light at controlled wavelengths in order to treat a variety of medical disorders, including seasonal affective disorder (SAD), circadian rhythm sleep-wake disorders, cancers, and skin wound infections. Treating skin conditions such as neurodermatitis, psoriasis, acne vulgaris, and eczema with ultraviolet light is called ultraviolet light therapy. Medical uses Nutrient deficiency Vitamin D deficiency Exposure to light to wavelengths of 290-300 nanometers enables the body to produce vitamin D3 to treat vitamin D3 deficiency. Ultraviolet B Light Emitting Diodes (LEDs) Are Efficient and Effective in Producing Vitamin D3 in Human Skin Skin conditions Light therapy treatments for the skin usually...