Systems and methods for determining one or more temperatures within a phototherapy blanket use or include one or more temperature sensors and a set of light sources to determine a temperature of a subject undergoing phototherapy within the phototherapy blanket and estimate a core temperature of the subject based on, at least, the temperature. The phototherapy blanket may include a thicker region having a higher thermal insulation than one or more other regions of the phototherapy blanket. By virtue of measuring the temperature at or near the thicker region, the uncertainty in the relation between a temperature and the subject's core temperature may be reduced, for more accurate temperature determination within the phototherapy blanket.
