Cycled light in the intensive care unit for preterm and low birth weight infants.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized and quasi-randomized trials
PubMed 39699174 · doi:10.1002/14651858.CD006982.pub5
What was done
This Cochrane systematic review update evaluated randomized controlled trials (RCTs) and quasi-RCTs assessing cycled light (artificial light-dark cycles) compared with near darkness/dimmed light or continuous bright light for preterm (<37 weeks postmenstrual age) or low birth weight (<2500 g) infants in neonatal intensive care or step-down units. Databases (CENTRAL, PubMed, Embase, registries) were searched through September 2023. Primary outcomes were growth at 3 and 6 months corrected age, major neurodevelopmental disability, and adverse effects. Secondary outcomes included retinopathy of prematurity (ROP), duration of initial hospitalization, duration of oxygen treatment, and parent satisfaction. Quality and certainty were assessed using Cochrane risk of bias and GRADE.
What was found
The review included 20 studies (1633 infants), with 11 studies (1126 infants) contributing to meta-analyses. - Cycled light vs. near darkness/dimmed light: Cycled light had very uncertain effects on weight at 3 months (MD 24.79, 95% CI -262.33 to 311.91; 2 studies, 187 infants), weight at 6 months (MD 202, 95% CI -109.68 to 513.68; 1 study, 147 infants), any stage ROP (RR 0.89, 95% CI 0.76 to 1.03; 3 studies, 307 infants), severe ROP stage 3 or higher (RR 0.98, 95% CI 0.59 to 1.61; 4 studies, 454 infants), and duration of hospitalization (MD -3.04 days, 95% CI -7.86 to 1.78; 5 studies, 550 infants). - Cycled light vs. continuous bright light: Cycled light may reduce hospitalization duration (MD -9.86 days, 95% CI -10.09 to -9.63; 5 studies, 499 infants), but certainty is very low. - No data were reported for major neurodevelopmental disability or adverse effects in either comparison.
Why it matters
Despite theoretical rationale that artificial circadian light cues support development, current trial evidence is of very low certainty and insufficient to determine whether cycled light improves clinical outcomes in preterm infants.
Limits
All 20 included trials had high or unclear risk of bias. The evidence across all analyzed outcomes was rated very low certainty under GRADE due to risk of bias, small sample sizes, and wide confidence intervals. Critical primary outcomes including major neurodevelopmental disability and adverse effects were not reported by any included study.
Cited by
- contradicts Regularizing the light-dark cycle in neonatal intensive care units increases blood oxygen saturation by 50% to 60%, boosts weight gain, and allows infants to be discharged about five weeks earlier.