Autonomic Control of Heart Rate During Sleep Is Depressed in Young Children With Prader-Willi Syndrome.

Children with Prader-Willi syndrome are at increased risk of both obstructive and central sleep apnoea. In addition, these children have impaired autonomic control, which may be exacerbated by sleep apnoea. The aim of this study was to compare autonomic control using heart rate variability and nocturnal dipping of heart rate in children with Prader-Willi syndrome and typically developing children. We identified 50 children with Prader-Willi syndrome and matched them for age, obstructive and central apnoea-hypoponea index, body mass index and sex to 50 typically developing children. All children underwent overnight polysomnography. Time and frequency domain heart rate variability were analysed during N2, N3, REM and total sleep, and nocturnal dipping of heart rate from wake was calculated. Children with Prader-Willi syndrome had reduced time domain heart rate variability in REM, reduced low frequency power in N2, higher heart rate in REM and total sleep (p < 0.05 for all) and reduced fall in heart rate from wake to REM (p < 0.05). When stratified into age groups, similar results were found in children ≤ 1 and > 1 ≤ 6 years, with no differences between groups in children > 6 years of age. The significant reduction in LF power and nocturnal dipping indicates children with Prader-Willi syndrome have delayed maturation of autonomic control, particularly below 6 years of age. Investigating the impact of age on heart rate variability longitudinally and treatments such as growth hormone remains to be elucidated.