Temporal and bidirectional associations between sleep, physical activity, and emotional self-regulation in toddlers

Sleep, physical activity (PA), and emotional self-regulation (ESR) are cross-sectionally associated; however, their temporal and bidirectional associations in toddlers remain unclear [1]. This is the first study to examine the temporal and bidirectional associations between toddlers’ sleep, physical activity, and ESR. Baseline (T0) and six-month post-baseline (T1) data from 1149 toddlers (2.9 ± 0.4 year.) from Let’s Grow were analysed. Parents reported their toddlers’ average nighttime sleep and naps (summed to calculate total sleep). Sleep behaviour scores (bedtime resistance, bedtime routine, nighttime waking, sleep duration, and sleep-onset delay scores) were assessed via the Child Sleep Habits Questionnaire and Brief Infant Sleep Questionnaire-revised. Total physical activity and moderate-to vigorous-intensity physical activity were assessed via a 3-item parent survey. ESR was assessed using the adapted Fast Track Project Child Behaviour Questionnaire (4-item). Cross-lagged panel models, adjusted for age, sex, parental education and trial group, were used. Findings suggest no temporal associations between PA and ESR. Nighttime sleep predicted better ESR (β = 0.06; CI 95 0.01, 0.11; p = 0.02) and naptime (β= -0.06; CI 95 -0.11, -0.01; p = 0.03) predicted poorer ESR, but total sleep quantity showed no temporal associations with ESR. Poor sleep behaviours (bedtime resistance, nighttime waking, and sleep duration) scores predicted poorer ESR (all p < 0.001). Poor ESR only predicted increased sleep onset delay (β= -0.06; CI 95 -0.12, -0.01; p = 0.03). No bidirectional associations between the constructs were observed. While PA did not predict ESR, nighttime sleep and certain sleep behaviours did; however, nap findings require caution given potential intervention or power limitations. The findings suggest sleep as a key health behaviour influencing toddlers’ ESR skills.