Premature baby in an incubator under phototherapy to treat jaundice. Jaundice is caused by the deposition of excess pigment (bilirubin) in the skin tissues. Jaundice is characterised by the yellow discolouration of the skin and eyes. The blue light from the phototherapy helps to break down the bilirubin, which will then be excreted through urination. It is important to protect the babies yes as a way of precaution.