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.