Timing for the Introduction of Cycled Light for Extremely Preterm Infants: A Randomized Controlled Trial

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Preterm infants have poorer orientation, self‐regulation, and reflexes and more excitability, hypotonia, and hypertonia at 40 weeks postmenstrual age (PMA) when compared to term infants (Pineda et al., 2013), but preterm infants’ growth and developmental outcomes vary with illness severity and degree of neurological insult (Boyle et al., 2012; Ge et al., 2013). Unexplained variations in outcomes exist even among healthy preterm infants (Schneider et al., 2014; Vohr, 2014). The variations in preterm infants’ outcomes have led to speculation that the neonatal intensive care unit (NICU) environment and light in particular may negatively affect the health and development of these infants, due to atypical sensory stimulation (Gressens, Rogido, Paindaveine, & Sola, 2002; Lickliter, 2000a) and the interruption of circadian rhythm development following preterm birth (Rivkees, 2003).
The sequential onset of fetal sensory system functioning, from somesthetic to vestibular, proprioceptive, olfactory, auditory, and visual (Gottlieb, 1971), and the relatively quiet intrauterine environment naturally limits sensory input, while the NICU environment provides atypical amounts of sensory stimulation following preterm delivery (Lickliter, 2000b). The fetus normally develops in a rich circadian environment, including maternal hormones and rest‐activity cycles while remaining in near‐darkness, but the NICU environment provides limited circadian cues and significant light exposure depending upon individual nursery practices. Factors with the potential to impact growth and circadian rhythm development in the NICU include light levels during the day and night (Watanabe et al., 2013), physical caregiving routines (Glotzbach, Edgar, Boeddiker, & Ariagno, 1994), and the timing and content of enteral feeding (Arslanoglu, Bertino, Nicocia, & Moro, 2012; Cubero et al., 2006; Glotzbach et al., 1994).
For extremely preterm infants (≤25 weeks) with prolonged intensive care stays, the unpredictable light environment of the inpatient setting has a greater potential for negative influences than the cycled light environment of the normal newborn. In a systematic review by the Cochrane Collaboration (Morag & Ohlsson, 2013), authors suggested that most preterm infant outcomes including growth, day‐night activity, and length of hospital stay trended better with cycled light than either continuous near‐darkness or bright light. However, few studies have been published, and all with small sample sizes (Boo, Chee, & Rohana, 2002; Brandon, Holditch‐Davis, & Belyea, 2002; Guyer et al., 2012, 2015; Mirmiran, Baldwin, & Ariagno, 2003; Rivkees, Mayes, Jacobs, & Gross, 2004; Vasquez‐Ruiz et al., 2014), and no clinical recommendation has been made.
The objective of this longitudinal randomized controlled trial was to evaluate infant health and developmental outcomes when provided early cycled light (ECL, beginning at 28 weeks PMA) versus late cycled light (LCL, beginning at 36 weeks PMA) in preterm infants born at ≤28 weeks gestation. We hypothesized that when compared to infants receiving LCL, infants receiving ECL would gain weight faster, be discharged from the hospital earlier with lower costs, and have better sleep and neurodevelopmental (mental, motor, visual acuity) outcomes. Retinopathy of prematurity (ROP) and hearing outcomes were measured to insure safety; we hypothesized there would be no differences between the ECL and LCL interventions, based on previous evidence that reduced light exposure has no effect on ROP severity (Jorge, Jorge, & El Dib, 2013) or sensory development (Brandon et al., 2002).
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