OBJECTIVE: We investigate whether double phototherapy reduces total serum bilirubin concentration faster than single light during intensive phototherapy with high levels of irradiance using light-emitting diodes.

STUDY DESIGN: Eighty-three infants with gestational age ⩾33 weeks and uncomplicated hyperbilirubinemia were randomized to either double (n=41) or single phototherapy (n=42) for 24 h. The mean irradiance was 64.8 μW cm-2 nm-1 from above and 39 μW cm-2 nm-1 from below.

RESULTS: The percentage decreases of total serum bilirubin after 12 h of double vs single phototherapy were (mean (95% confidence interval (CI))) 39% (37 to 42) vs 30% (27 to 32), respectively (P<0.001). After 24 h, the decreases were 58% (56 to 61) vs 47% (44 to 50), respectively (P<0.001). The results were still significant after adjustment for confounding. The only side effect was loose stools.

CONCLUSION: Even with intensive phototherapy increasing spectral power by increasing the irradiated body surface area, the efficacy of phototherapy is improved.