Researchers in Japan have developed the first wearable devices to precisely monitor jaundice, a yellowing of the skin caused by elevated bilirubin levels in the blood that can cause severe medical conditions in newborns. Jaundice can be treated easily by irradiating the infant with blue light that breaks bilirubin down to be excreted through urine. The treatment itself, however, can disrupt bonding time, cause dehydration and increase the risks of allergic diseases. Neonatal jaundice is one of the leading causes of death and brain damage in infants in low- and middle-income countries.