A phototherapy device for treating neonatal hyperbilirubinemia comprises a plurality of LEDs coupled to a support structure configured to absorb and dissipate heat generated by the LEDs without requiring a fan. The LEDs provide a uniform dose of radiation on a treatment surface of the subject over a distance range of 20 cm to 45 cm. The support structure can comprise a heat-conductive metal plate. The LEDs have an emission range of 400 nm to 520 and a light output intensity of at least 30 μW/cm2/nm and at most 65 μW/cm2/nm at the treatment surface. The device can be adjustably coupled to a mounting structure. Power supplied to the LEDs is adjustable based on the total number of hours of use of he LEDs, the intensity of the LED radiation, the distance between the LEDs and the treatment surface, and/or the tilt or orientation of the phototherapy device.