A light/dark cycle in the NICU accelerates body weight gain and shortens time to discharge in preterm infants

Early Hum Dev. 2014 Sep;90(9):535-40. doi: 10.1016/j.earlhumdev.2014.04.015. Epub 2014 May 13.


Background: Bright constant light levels in the NICU may have negative effects on the growth and development of preterm infants

Objective: The aim of this study is to evaluate the benefits of an alternating light/dark cycle in the NICU on weight gain and early discharge from the therapy in premature infants.

Patients and methods: A randomized interventional study was designed comparing infants in the NICU of Hospital Juarez de México, exposed from birth either to an LD environment (LD, n=19) or to the traditional continuous light (LL, n=19). The LD condition was achieved by placing individual removable helmets over the infant's heads. Body weight gain was analyzed, as the main indicator of stability and the main criteria for discharge in preterm infants born at 31.73±0.31week gestational age.

Results: Infants maintained in an LD cycle gained weight faster than infants in LL and therefore attained a shorter hospital stay, (34.37±3.12 vs 51.11±5.29days; P>0.01). Also, LD infants exhibited improved oxygen saturation and developed a daily melatonin rhythm.

Conclusions: These findings provide a convenient alternative for establishing an LD environment for preterm healthy newborns in the NICU and confirm the beneficial effects of an alternating LD cycle for growth and weight gain and for earlier discharge time. Here we provide an easy and practical alternative to implement light/dark conditions in the NICU.

Keywords: Chronotherapy; Circadian rhythms; Melatonin; Neonatology.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Darkness*
  • Heart Rate
  • Humans
  • Infant, Newborn
  • Intensive Care Units, Neonatal*
  • Length of Stay*
  • Light*
  • Melatonin / analysis
  • Mexico
  • Milk, Human
  • Oximetry
  • Oxygen / analysis
  • Patient Discharge*
  • Saliva / chemistry
  • Weight Gain*


  • Melatonin
  • Oxygen