Preschool children's high-frequency heart rate variability during low and high emotional challenge in relation to their self-regulation

High-frequency heart rate variability (hf-HRV) theoretically provides a biomarker for self-regulation, although studies with young children offer mixed findings regarding the relevance of emotional demands in this link. We aimed to describe variation in children's hf-HRV during tasks with relatively high and low emotional load and to determine the relation of hf-HRV during these tasks to different behavioural measures of children's self-regulation. Electrocardiograms were recorded in 80 3–5-year-olds (M = 57 months; 54% male, 47% female; 87% White, 8% mixed/other race, 2% African American/Black, 1% were Asian and 1% Hispanic/Latinx) whilst they completed a Go/No-go task with low emotional load and an emotionally challenging Delay Frustration task. Mean hf-HRV was similar across these tasks, although it increased during a between-task rest interval. Accounting for age, gender and caregiver education, hf-HRV during the Go/No-go task correlated with task performance, whereas hf-HRV during the emotional task correlated with caregiver-reported regulation (Psuedo R² = 03–0.05). Greater hf-HRV withdrawal during the tasks correlated with weaker Go/No performance and increased behavioural frustration (Psuedo R² = 0.08–0.13). Children's maintenance of hf-HRV during emotional and cognitive challenges may support their effective self-regulation.