MODEL RELEASED. Phototherapy. Nurse looking after a newborn baby undergoing phototherapy in an incubator to treat neonatal jaundice. Jaundice causes yellowing of the skin and the whites of the eyes due to the accumulation of bilirubin, a blue pigment, in the blood. It is a common condition in newborn babies, but rarely requires treatment. The ultraviolet light causes the chemical breakdown of bilirubin, which is then excreted in the urine. Incubators are most often used for premature babies. They allow the temperature, humidity and oxygen concentration of the babys environment to be controlled.