Comparing the Effects of Cycled and Constant Lighting on Weight Gain and Length of Stay in Neonatal Intensive Care Unit among Premature Neonates: A Two-Group Randomized Controlled Clinical Trial

Background: Environmental lighting can potentially affect weight gain and the length of stay in Neonatal Intensive Care Unit (NICU) among premature neonates. Yet, there are controversies about the best way of lighting in these units. Objectives: The aim of this study was to compare the effects of cycled lighting (CL) and constant lighting on weight gain and the length of stay in NICU among premature neonates. Methods: This two‑group randomized controlled trial was conducted on 78 premature neonates hospitalized in NICU of Mofid Children’s Hospital, Tehran, Iran. Neonates in the intervention group were treated, for 15 days, with CL. Neonates in the control group were exposed to constant lighting of the unit. Neonates in both groups were weighed every morning at 07:30 and their length of stay in the unit was recorded in days. Data analysis was done through Chi‑square test, independent‑samples t‑test, and Mann–Whitney U‑test and the two‑way analysis of variance. The random‑effects spline model was employed to compare the groups in terms of the trend of weight variations over time. Results: Neonates’ weight in both groups decreased during the first 7 days of hospitalization and then started to increase from the 8th day. The groups did not significantly differ from each other respecting neonates’ weight in the first 8th days (P = 0.857), while weight mean in days 9–15 in the intervention group was significantly greater than the control group by at least 25.25 g in the 9th day and 159.95 g in the 15th day (P < 0.001). Statistically significant differences were observed between the two groups in terms of daily weight gain (14.63 ± 5.64, 29.17 ± 7.32) with gender being unadjusted (P = 0.005) and adjusted (P = 0.001). However, no significant between‑group differences were observed in terms of the length of stay (18.18 ± 10.21, 18.29 ± 12 days) in NICU with gender being unadjusted (P = 0.939) and adjusted (P = 0.990). Conclusions: CL is effective in improving premature neonates’ weight gain but ineffective in shortening their stay in NICU.