Background: Indirect hyperbilirubinemia (IHB) is a common neonatal condition, affecting over 60% of term and 80% of preterm infants. Phototherapy is the most widely used, safe, and non-invasive treatment; however, scattering of phototherapy light decreases treatment efficacy, prolongs therapy duration, and increases the risk of side effects. Reflective materials have been suggested to enhance phototherapy effectiveness, yet studies comparing different reflector types remain limited. Aim: This study aims to compare the effects of using reflective materials (white cloth or aluminum foil) during phototherapy on total serum bilirubin levels, phototherapy duration, length of hospital stay, vital signs, side effects, and nurses' satisfaction in neonates with physiological IHB.

Methods: This single-center, single-blind, randomized controlled trial will be conducted at Ankara University Faculty of Medicine, Cebeci Neonatal Intensive Care Unit. A total of 81 neonates with gestational age 35-42 weeks and total serum bilirubin levels of 15-20 mg/dl will be randomly assigned into three groups: (1) phototherapy with white cloth reflectors, (2) phototherapy with aluminum foil reflectors, and (3) standard phototherapy (control). Data will be collected using an Introductory Information Form, Daily Follow-up Chart, Side Effect Observation Form, and Nurse Satisfaction Questionnaire. Statistical analyses will include parametric and non-parametric tests based on distribution assumptions, with significance set at p\<0.05. Expected

Results: It is hypothesized that the use of reflective materials will result in faster reduction of total serum bilirubin, shorter phototherapy and hospitalization durations, more stable vital signs, fewer side effects, and higher nurse satisfaction compared with standard phototherapy.

Conclusion: The study will provide evidence on the comparative effectiveness of two low-cost reflector materials in enhancing phototherapy outcomes, potentially offering a practical and efficient strategy for neonatal hyperbilirubinemia management.