What is the process of treatment using light rays or waves called?

The process of treatment using light rays or waves is known as light therapy. This therapeutic approach utilizes specific wavelengths of light to promote healing and is often used to treat various conditions, such as skin disorders, mood disorders (like seasonal affective disorder), and even certain types of pain. Light therapy works by exposing the skin or eyes to specific frequencies of light, which can stimulate various biological processes in the body, such as increasing serotonin levels or promoting collagen production in the skin.

Color therapy, while related to the use of light, specifically focuses on the psychological and physical effects of colors on individuals, rather than the medical applications of light wavelengths. Heat therapy employs thermal energy to relieve pain and improve circulation, predominantly dealing with temperature rather than light. Sound therapy, on the other hand, uses sound waves to promote healing and relaxation, completely differing from light-based treatments. Therefore, light therapy stands out as the correct answer given its focus on using light as a therapeutic medium.