Full-spectrum light travels from the eye to the brain, where it triggers the hypothalamus to send chemical messengers to regulate the autonomic functions of the body, such as blood pressure, breathing, digestion, and the immune system, as well as the body’s circadian rhythm. In order to maintain health, it may be important to be exposed to light containing the full wavelength spectrum found in natural light. Full-spectrum light therapy, bright light therapy, and ultraviolet light therapy are used by some clinicians for treating conditions that range from seasonal affective disorder to bulimia, and new applications are continually being suggested.