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Assessment and Evaluation of the High Risk Neonate: The NICU Network Neurobehavioral Scale
Published on: August 25, 2014
Cyclicity of neonatal sleep behaviors at 25 to 30 weeks' postconceptional age
Mark S Scher1, Mark W Johnson, Diane Holditch-Davis
1Division of Pediatric Neurology, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio 44106, USA. Mark.Scher@uhhs.com
Insights
Preterm neonates between 25-30 weeks postconceptional age (PCA) show sleep state cyclicity. This ultradian rhythm indicates early brain development in premature infants.
Area of Science:
- Neonatal Neuroscience
- Sleep Medicine
- Developmental Biology
Background:
- Previous research indicated rudimentary sleep state cyclicity in preterm neonates after 30 weeks postconceptional age (PCA).
- Sleep cyclicity stability is typically observed only after 36 weeks PCA.
Purpose of the Study:
- To determine if sleep state cyclicity is present in neonates between 25-30 weeks PCA.
- To evaluate sleep cyclicity using specific criteria for state identification in early preterm infants.
Main Methods:
- A subset of 33 preterm infants (25-30 weeks PCA) underwent EEG sleep studies.
- Sleep state cyclicity was assessed by a neonatal neurophysiologist using Rapid Eye Movement (REM) counts and EEG discontinuity.
- Autocovariance analysis was employed to determine mean cycle duration.
Main Results:
- Sleep state cyclicity was observed in a majority of neonates within the 25-30 week PCA range.
- The mean cycle duration was determined to be 68 +/- 19 minutes.
- Nine infants exhibited absent or poor sleep cyclicity.
Conclusions:
- Sleep state cyclicity is expressed in the majority of neonates between 25 and 30 weeks PCA.
- This finding suggests an ultradian biologic rhythm present during early perinatal brain development.
- The study provides evidence for early expression of sleep cyclicity in preterm infants.
Abstract:
Previous sleep studies of preterm neonates describe the rudimentary expression of sleep state cyclicity after 30 wk postconceptional age (PCA), with stability over multiple cycles only after 36 wk PCA. The research objective for this study was to determine whether sleep state cyclicity was expressed in neonates of 25-30 wk PCA, using two criteria for state identification. Our neonatal sleep consortium includes a total cohort of 359 children who were healthy and medically ill neonates who were recruited from three obstetric-neonatal services and received multiple-hour EEG sleep studies. A subset of the 33 youngest preterm infants were selected to evaluate the first of serial 2- to 3-h EEG-sleep recordings to assess the presence of sleep state cyclicity. One neonatal neurophysiologist visually assigned EEG-sleep characteristics for each record. Rapid eye movement (REM) counts and EEG discontinuity were specifically chosen to assess whether sleep cyclicity was expressed. A combined measure of REM and EEG discontinuity were used in an autocovariance analysis to assess cycling and mean cycle duration. A mean cycle duration of 68 +/- 19 min with a range of 37-100 min was determined from the REM-EEG discontinuity state for 24 neonates. The remaining nine infants had absent or poor sleep cyclicity. Sleep state cyclicity is expressed for a majority of neonates between 25 and 30 wk PCA, reflecting an ultradian biologic rhythm during the early perinatal stage of brain development.
