P042 Actigraphy-derived sleep characteristics of healthy children who benefit the most from a sleep extension protocol

INTRODUCTION: Although experimental manipulation of sleep can extend children’s sleep via earlier bedtimes, this is not always possible. We aimed to determine true sleep gains made with a one hour earlier bedtime, and which actigraphy variables at baseline predicted the best gains. METHODS: Secondary analysis within a randomised crossover trial (99 children; 49.5% female; mean age=10.3 years, range 8-12 years). Each child underwent one week of sleep restriction and extension in a random order (1h later or earlier bedtime respectively) separated by a one-week washout. Sleep data comparing baseline and extension weeks were analysed using linear or logistic regression, controlling for randomised order. RESULTS: The mean (SD) difference in total sleep time (TST) with sleep extension was 14.3 (44.1) min/night. Thirty-three percent extended their sleep by at least 30 min/night. At baseline, having lower sleep quantity (TST) and quality (efficiency, WASO, waking frequency) significantly predicted more sleep gain. For each 1 h lower TST at baseline, 29.7 min (95% CI: 19.4, 40.1) more sleep was gained. At baseline, a TST below 8 h 49 min was the optimal cut-point to predict whether children could extend their sleep by at least 30 min/night (found in 40% of children). Adjusting for relevant demographics and sleep hygiene made little difference. CONCLUSION: Children who slept less than 8 h 49 min/night obtained the most sleep gain from a 1 hour earlier bedtime maintained over a week. Maintenance over the longer term is unknown. Findings have implications for understanding the sleep requirements of children.