Light and color have been valued throughout history as sources of healing. Today, the therapeutic applications of light and color are being investigated in major hospitals and research centers worldwide. Results indicate that full-spectrum, ultraviolet, colored, and laser light can have therapeutic value for a range of conditions from chronic pain and depression to immune disorders and cancer.

  Many health disorders can be traced to problems with the circadian rhythm, the body's inner clock, and how it governs the timing of sleep, hormone production, body temperature, and other biological functions. Disturbances in this rhythm can lead to health problems such as depression and sleep disorders. Natural sunlight and various forms of light therapy can help reestablish the body's natural rhythm and are becoming an integral treatment for many related health conditions.

  More recently, the ability of light to activate certain chemicals has become the basis of treatment for skin disorders such as psoriasis and for certain forms of cancer. Exposure to ultraviolet light under controlled conditions has also proved beneficial for certain conditions, particularly when combined with light-sensitive medications.