Cycled light in the intensive care unit for preterm and low birth weight infants

Background The potential benefits and harms of different lighting in neonatal units have not been quantified. Objectives To compare the effectiveness of cycled lighting (CL) (approximately 12 hours of light on and 12 hours of light off) with irregularly dimmed light or near darkness (ND) and with continuous bright light (CBL) on growth in preterm infants at three and six months of age. Search strategy Electronic searches of the literature were conducted (in May 2010) of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL and abstracts from Pediatric Academic Societies' annual meetings. Selection criteria Randomised or quasi-randomised trials of CL versus ND or CBL in preterm and low birth weight infants. Data collection and analysis Data collection and analyses were performed according to the methods of the Cochrane Neonatal Review Group. Main results Five studies enrolling 387 infants compared CL to ND. No study reported on weight at three or six months. In one study (n = 40) there was no statistically significant difference in weight at four months between the CL and the ND groups. In another study (n = 62) the ratio of day-night activity prior to discharge favoured the CL group (mean difference 0.18, 95% CI 0.17 to 0.19) indicating 18% more activity during day than night in the CL group compared to the ND group. Two studies (n = 189) reported on retinopathy of prematurity (stage >= 3). There was no statistically significant difference between the CL and ND groups (typical RR 0.53, 95% CI 0.25 to 1.11, I-2 = 0%; typical RD -0.09, 95% CI -0.19 to 0.01, I-2 = 0%). Two studies enrolling 82 infants compared CL to CBL. One study (n = 41) reported higher mean weight at three months corrected age in infants cared for in the CL nursery (P < 0.02) and lower mean number of hours spent awake in 24 hours at three months (P < 0.005). In one study (n = 41) days on a ventilator were reduced in the CL group (mean difference -18, 95% CI -31 to -5 days). For many outcomes the trends favoured CL versus ND as well as CL versus CBL. Authors' conclusions Trials assessing the effect of CL have enrolled 469 infants. Trends for many outcomes favoured cycled light (CL) compared to near darkness (ND) and CL compared to continuous bright light (CBL) The studies may have lacked significance due to a lack of statistical power. Future research should focus on comparing CL to ND.