Melanin (Greek μέλας, black) is a class of com- pounds that serves as a pigment.The most common form of biological melanin is Eumelanin , a brown-black polymer of dihydroxyindole carboxylic acid, and their reduced forms. Another common form of melanin is pheomelanin, a of benzothiazine units largely responsible for red hair and freckles. The increased production of melanin in human skin is called melanogenesis. It is stimulated by the DNA damages that are caused by UVB-radiation. Eumelanin is found in hair and skin, and colors hair grey, black, yellow, and brown. In humans, it is more abundant in peoples with dark skin. Pheomelanin is also found in hair and skin and is found in lighter skinned people. Pheomelanin becomes carcinogenic when exposed to the ultraviolet rays of the sun.
A recent placebo-controlled study showed evidence of trans-cranial bright light’s effect to brain functions when administered through the ear. Bright light stimulation was found to increase activity in brain areas related to processing of visual sensory information and tactile stimuli. The findings are the first ever published scientific article about functional modulation of the brain with bright light delivered to the brain through the ears. (Source) Continue reading