Randomized controlled study of the effects of different durations of light exposure on weight gain by preterm infants in a neonatal intensive care unit

A randomized controlled study was carried out on 96 preterm infants (>37 wk) with birthweight less than 2000 g admitted to a neonatal intensive care unit. The aim was to compare the weight gain between preterm infants exposed to 12 h cyclical lighting (intensity of light: 78.4 ± 24.7 lux, mean ± SD) and those exposed to a continuously dim environment (5.9 ± 1.9 lux). The exclusion criteria were infants with major congenital malformations or who needed continuous lighting for treatment procedure and care. From day 7 of life until discharge, 50 infants were randomized to receive 12 h cyclical lighting and 46 infants to a continuously dim environment. There was no significant difference in the mean birthweight (12 h lighting vs continuously dim: 1482 vs 1465 g, p = 0.8), mean gestational age (31.6 vs 31.4 wk, p = 0.6), median duration of hospital stay (28.5 vs 28.5 d, p = 0.8), mean age to regain birthweight (13.0 vs 12.9 d, p = 0.3), mean weight gained by day 14 (27.6 vs 36.2 g, p = 1.0), median weight gain per day (11.9 vs 12.2 g, p = 0.9) or median body weight on discharge (1800 vs 1800g, p = 0.4) between the two groups of infants. Conclusion : Exposing preterm infants to either 12 h cyclical lighting or continuously dim environment did not have any significant effect on their weight gain during the neonatal period.