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Updated: May 7, 2026

Measuring Cardiac Autonomic Nervous System (ANS) Activity in Toddlers - Resting and Developmental Challenges
Published on: February 25, 2016
Nocturnal autonomic function in preschool children with sleep-disordered breathing
Lauren C Nisbet1, Stephanie R Yiallourou, Gillian M Nixon
1The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia.
Background:
Obstructive sleep apnea (OSA) is associated with autonomic dysfunction in adults and school-aged children; however, this association has not been investigated in preschool children. We aimed to analyze heart rate variability (HRV) and catecholamine levels in preschool children with OSA.
Methods:
One hundred and forty-two snoring children aged 3-5years and 38 nonsnoring control group children underwent overnight polysomnography (PSG). Nocturnal urinary catecholamines were measured in 120 children. Children were grouped according to their obstructive apnea-hypopnea index (OAHI) (control [no snoring], OAHI⩽1event/h; primary snoring, OAHI⩽1event/h; mild OSA OAHI>1⩽5events/h; moderate to severe [MS] OSA, OAHI>5events/h). The HRV parameters for each child were averaged during rapid eye movement (REM) and non-REM (NREM) sleep.
Results:
During stable sleep, low-frequency (LF) HRV was similar between groups. High-frequency (HF) HRV was higher in the MS OSA group compared with the control group during all sleep stages (NREM sleep stages 1 and 2 [NREM1/2], 4234±523ms(2) vs 2604±457ms(2); NREM sleep stages 3 and 4 [NREM3/4], 4152±741ms(2) vs 3035±647ms(2); REM, 1836±255ms(2) vs 1456±292ms(2); P<.01 for all). The LF/HF ratio was lower in the MS OSA group compared with the control group (NREM1/2, 0.4±0.06 vs 0.7±0.05; NREM3/4, 0.3±0.06 vs 0.4±0.05; REM, 0.8±0.1 vs 1.3±0.1; P<.01 for all). Catecholamine levels were not different between groups.
Conclusions:
In preschool children, OSA is associated with altered HRV, largely due to the HF fluctuations in heart rate (HR) which occur during respiratory events and are still evident during stable sleep. The preschool age may represent a window of opportunity for treatment of OSA before the onset of the severe autonomic dysfunction associated with OSA in adults and older children.
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