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This link also gives some effects through skin.
The blue light found to be successful in the treatment of neonatal jaundice has also been shown to be effective in the treatment of rheumatoid arthritis. In studies by S. F. McDonald, most of those exposed to blue light for variable periods up to fifteen minutes experienced a significant degree of pain relief. It was concluded that the pain reduction was directly related both to the blue light and the length of exposure to it. Blue light is also used in healing injured tissue and preventing scar tissue, in the treatment of cancers and nonmalignant tumors, as well as skin and lung conditions.
n 1990, scientists reported to the annual conference of the American Association for the Advancement of Science on the successful use of blue light in the treatment of a wide variety of psychological problems, including addictions, eating disorders, impotence, and depression.
http://innerself.com/Health/Color_Therapy_part_2.htm
This link also gives some effects through skin.