Electroencephalographic sleep macrostructure and sleep spindles in early infancy

Soraia Ventura; Sean R Mathieson; John M O'Toole; Vicki Livingstone; Mary-Anne Ryan; Geraldine B Boylan

doi:10.1093/sleep/zsab262

Electroencephalographic sleep macrostructure and sleep spindles in early infancy

Sleep. 2022 Jan 11;45(1):zsab262. doi: 10.1093/sleep/zsab262.

Authors

Soraia Ventura^{1

2}, Sean R Mathieson^{1

2}, John M O'Toole^{1

2}, Vicki Livingstone^{1

2}, Mary-Anne Ryan^{1

2}, Geraldine B Boylan^{1

2}

Affiliations

¹ Department of Paediatrics & Child Health, University College Cork, Cork, Ireland.
² INFANT Research Centre, University College Cork, Cork, Ireland.

Abstract

Study objectives: Sleep features in infancy are potential biomarkers for brain maturation but poorly characterized. We describe normative values for sleep macrostructure and sleep spindles at 4-5 months of age.

Methods: Healthy term infants were recruited at birth and had daytime sleep electroencephalograms (EEGs) at 4-5 months. Sleep staging was performed and five features were analyzed. Sleep spindles were annotated and seven quantitative features were extracted. Features were analyzed across sex, recording time (am/pm), infant age, and from first to second sleep cycles.

Results: We analyzed sleep recordings from 91 infants, 41% females. Median (interquartile range [IQR]) macrostructure results: sleep duration 49.0 (37.8-72.0) min (n = 77); first sleep cycle duration 42.8 (37.0-51.4) min; rapid eye movement (REM) percentage 17.4 (9.5-27.7)% (n = 68); latency to REM 36.0 (30.5-41.1) min (n = 66). First cycle median (IQR) values for spindle features: number 241.0 (193.0-286.5), density 6.6 (5.7-8.0) spindles/min (n = 77); mean frequency 13.0 (12.8-13.3) Hz, mean duration 2.9 (2.6-3.6) s, spectral power 7.8 (4.7-11.4) µV2, brain symmetry index 0.20 (0.16-0.29), synchrony 59.5 (53.2-63.8)% (n = 91). In males, spindle spectral power (µV2) was 24.5% lower (p = .032) and brain symmetry index 24.2% higher than females (p = .011) when controlling for gestational and postnatal age and timing of the nap. We found no other significant associations between studied sleep features and sex, recording time (am/pm), or age. Spectral power decreased (p < .001) on the second cycle.

Conclusion: This normative data may be useful for comparison with future studies of sleep dysfunction and atypical neurodevelopment in infancy. Clinical Trial Registration: BABY SMART (Study of Massage Therapy, Sleep And neurodevelopMenT) (BabySMART)URL: https://clinicaltrials.gov/ct2/show/results/NCT03381027?view=results.ClinicalTrials.gov Identifier: NCT03381027.

Keywords: EEG; NREM; REM; infant; macrostructure; nap; neurodevelopment; sleep; spindles.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Electroencephalography
Female
Humans
Infant
Infant, Newborn
Male
Polysomnography
Sleep Stages*
Sleep*
Sleep, REM

Associated data

ClinicalTrials.gov/NCT03381027