This article is from the Alternative Medicine Therapies guide.
While some of the claims for the health benefits of light therapy are as yet unproved, it is known that adequate light is vital to many aspects of healthy living. For example, light is needed to maintain the body's circadian rhythms, or internal clock. These rhythms control numerous functions, from hormone levels to sleep and wake cycles. Studies show that the eye turns light into electrical impulses, which travel along the optical nerve to the brain, triggering the release of the mood-altering chemical, serotonin and other chemical messengers. Healthy levels of serotonin and other neurotransmitters are very much involved in one's emotional well-being.
Health problems can develop when the circadian rhythms are thrown off. This can occur when people spend much of their time indoors, work odd shifts, or fly across time zones, or when the amount of daylight decreases in the fall and winter. Bright light therapy helps the body restore its natural circadian rhythms.