As you know exposure of the jaundiced infant to blue, white or green light is effective in reducing the serum billirubin level. When bilirubin absorbs light, serveral types of photochemical reactions occur. The first is photoisomerization which occurs in the extravascular space of the skin. This coverts bilirubin produced in vivo by the breakdown of hemoglobin to a bilirubin isomer. This isomer diffuses into the blood and is bound to albumin, transported to the liver and excreted with the bile into the bowel. No conjugation is required.