Light therapy is the use of natural or artificial light to treat various ailments, but primarily depressive and sleep disorders. While exposure to the full-spectrum wavelength of natural sunlight is considered the best form of light therapy, it is not always possible for many people to get outdoors. Therefore, light therapists often recommend treatment with simulated sunlight from light boxes.

The form of light therapy most commonly used today is known as bright-light therapy. It requires that you sit near a special light box fitted with high-intensity light bulbs, which may provide either full-spectrum or white light. This type of light therapy has been proven to be particularly useful in treating seasonal affective disorder (SAD), also known as the "winter blues," a form of depression that occurs as the amount of daylight wanes with the change of seasons. It has also been shown to be effective for some sleep disorders. Studies have also shown light therapy to effective in the depression associated with PMS, chronic anxiety and panic attacks, severe jet lag, and eating disorders such as anorexia nervosa and bulimia.