Sleep state organisation of moderate to late preterm infants in the neonatal unit

Abstract

Background Sleep supports neurodevelopment and sleep architecture reflects brain maturation. This prospective observational study describes the nocturnal sleep architecture of healthy moderate to late preterm (MLP) infants in the neonatal unit at 36 weeks post menstrual age (PMA). Methods MLP infants, in the neonatal unit of a tertiary hospital in Ireland from 2017 to 2018, had overnight continuous electroencephalography (cEEG) with video for a minimum 12 h at 36 weeks PMA. The total sleep time (TST) including periods of active sleep (AS), quiet sleep (QS), indeterminate sleep (IS), wakefulness and feeding were identified, annotated and quantified. Results A total of 98 infants had cEEG with video monitoring suitable for analysis. The median (IQR) of TST in the 12 h period was 7.09 h (IQR 6.61–7.76 h), 4.58 h (3.69–5.09 h) in AS, 2.02 h (1.76–2.36 h) in QS and 0.65 h (0.48–0.89 h) in IS. The total duration of AS was significantly lower in infants born at lower GA (p = 0.007) whilst the duration of individual QS periods was significantly higher (p = 0.001). Conclusion Overnight cEEG with video at 36 weeks PMA showed that sleep state architecture is dependent on birth GA. Infants with a lower birth GA have less AS and more QS that may have implications for later neurodevelopment. Impact EEG provides objective information about the sleep organisation of the moderate to late preterm (MLP) infant. Quantitative changes in sleep states occur with each week of advancing gestational age (GA). Active sleep (AS) is the dominant sleep state that was significantly lower in infants born at lower GA. MLP infants who were exclusively fed orally had a shorter total sleep time and less AS compared to infants who were fed via nasogastric tube.

Reducing Noise in the NICU

“…For infants born prematurely who experience the third trimester in the NICU, sleep is likewise required for maturation of cortical gyri, expansion of white matter, and brain growth. [19][20][21][22][23] Sleep is essential for the learning process and acquiring new information because memories are consolidated and stored during sleep. Sleep rests neural connections, conserves energy, and enables the brain to encode new information.…”

“…23 In contrast, poor sleep quality is associated with neurodevelopmental impairments in infants, particularly those born prematurely who did not undergo neurologic development in utero during the third trimester. [19][20][21][22][23] Sleep typically occurs in a circadian rhythm, but high risk neonates do not exhibit this rhythmicity. 26 Interruption of sleep in the NICU environment impairs the development of cyclic sleep architecture, 20 , 26 , 27 contributing to suboptimal cognitive, developmental, and psychosocial outcomes.…”

“…Sleep is associated with rapid structural and functional changes in the brain during the third trimester of fetal life. For infants born prematurely who experience the third trimester in the NICU, sleep is likewise required for maturation of cortical gyri, expansion of white matter, and brain growth 19-23. Sleep is essential for the learning process and acquiring new information because memories are consolidated and stored during sleep.…”

“…In contrast, poor sleep quality is associated with neurodevelopmental impairments in infants, particularly those born prematurely who did not undergo neurologic development in utero during the third trimester 19-23. Sleep typically occurs in a circadian rhythm, but high risk neonates do not exhibit this rhythmicity 26.…”

“…Sleep typically occurs in a circadian rhythm, but high risk neonates do not exhibit this rhythmicity 26. Interruption of sleep in the NICU environment impairs the development of cyclic sleep architecture,20,26,27contributing to suboptimal cognitive, developmental, and psychosocial outcomes 20,28. Specifically, the deficiency of active sleep can impair transmission of information and decrease overall brain volume.…”