In 36-week-postconceptional age preterm infants, the supine sleeping position had less quiet sleep and was associated with greater heart rate variability during the first sleep cycle after the feeding. More awakenings were seen during all sleep states in the supine position. These data support the American Academy of Pediatrics recommendation for "Back to Sleep" for asymptomatic preterm infants because more awakenings and lower threshold for arousal may provide some benefit for the infant responding to a life-threatening event. However, further studies are needed to address positional effect on the physiologic measures in preterm infants at older ages (later stages of development). Precisely what constitutes the most healthy or advantageous sleep for newborn infants remains an important question.

ABSTRACT. Objective. The Neonatal Individualized Developmental Care Program (NIDCAP) for very low birth weight (VLBW) preterm infants has been suggested by Als et al to improve several medical outcome variables such as time on ventilator, time to nipple feed, the duration of hospital stay, better behavioral performance on Assessment of Preterm Infants' Behavior (APIB), and improved neurodevelopmental outcomes. We have tested the hypothesis of whether the infants who had received NIDCAP would show advanced sleep-wake pattern, behavioral, and neurodevelopmental outcome.Methods. Thirty-five VLBW infants were randomly assigned to receive NIDCAP or routine infant care. The goals for NIDCAP intervention were to enhance comfort and stability and to reduce stress and agitation for the preterm infants by: a) altering the environment by decreasing excess light and noise in the neonatal intensive care unit (

This study investigated the effect of intermediate nursery illumination on circadian rhythm and sleep development of preterm infants. Preterm infants were randomly assigned to one of two intermediate nursery rooms: a dimly lighted room, the dim (control) group, or a day-night lighted room, the cycled (intervention) group. Continuous rectal temperature and sleep were recorded at 36 wk postconceptional age (before discharge) and at 1 and 3 mo corrected age at home. Preterm infants are exposed to continuous low or unpredictable high illumination for several weeks or months in the neonatal intensive care unit (NICU) and intermediate care nursery. These infants are deprived of several potentially important maternal entrainment factors (1-4). This lack of maternal input and exposure to random/unpredictable lighting in the nursery may hinder the development of sleep and circadian rhythms and may adversely influence clinical outcome (5). It is hypothesized that regular lighting in the nursery will improve circadian rhythm development and thereby enhance clinical outcome. Indeed, earlier studies have shown beneficial clinical effects of cycled light in the nursery (6 -8). However, the shortor long-term influences of light on development of circadian rhythm were not examined in these studies. A prospective randomized study was initiated to address the hypothesis that cycled light before discharge may improve circadian organization and sleep compared with continuous dim lighting. METHODSPreterm infants who were admitted to our nursery at Lucile Packard Children's Hospital at Stanford were eligible. Exclusion criteria were short stay (Ͻ10 d) and transfer to another hospital, major congenital malformations, intrauterine growth retardation, grade 3 or 4 intraventricular hemorrhage, parenchymal injury including periventricular leukomalacia, prenatal infection, or substance abuse. When the clinical condition of an infant in the NICU was stable, he or she was transferred to the intermediate nursery and was randomly assigned to one of two groups: a dimly lighted room, the dim (control) group, or a day-night lighted room, the cycled (intervention) group. We assigned one room of our two-room intermediate care nursery to a continuous dim condition (dim room) in which the lighting remained low (below 20 lux) around the clock. The infant's incubator/bassinet was also covered by a nearly opaque blanket except during feeding or other interventions by parents and caregivers. This is the recommendation of the Neonatal Individualized Developmental Care Program (9), and during the time of this study, dim lighting 24 h/d was used as the standard practice at Stanford for all preterm infants. Infants in the cycled room also had their incubator/bassinet covered with the same type of blanket from 1900 h to 0700 h; however, the blanket was removed from 0700 h to 1900 h, at which time the room lighting was also turned up to standard lighting levels (approximately 300 lux) to produce a regular light-dark cycled condi-

Despite the commonly held belief, prone position did not substantially increase total sleep at these ages. On the other hand, prone sleeping decreased the number of sleep transitions at 1 month corrected age, increased QT and JT intervals, and reduced HRV, thereby potentially increasing the vulnerability for SIDS. This study supports "Back to Sleep" as the position of choice not only for term but also for preterm infants after discharge home.

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