This article is from the Alternative Medicine Therapies guide.
Color is a property of light, which consists of many different electromagnetic waves of energy. When light falls upon the photoreceptor cells of the retina, it is converted into electric impulses, which then travel to the brain and trigger the release of hormones.
It is well-established that the lack of sunlight experienced during the winter in northern climates causes depression in many people--a condition known as seasonal affective disorder (SAD). Daily exposure to full-spectrum light from a special bright-light box has been shown to improve SAD by suppressing daytime elevation of the hormone melatonin (a substance that promotes sleep) and increasing the amount of the mood-elevating brain chemical serotonin.
Proponents of color therapy reason that if light, as well as the absence of light, has such profound effects on health, then the individual colors that make up light must, too. No conclusive proof of this has ever been found, however.