Who Did It? Sleep, Source Memory, and Action Memory in Human 4-Year-Olds.

Sleep facilitates memory consolidation across the lifespan, but few studies have investigated underlying mechanisms in early development. The present study assessed the role of sleep timing after a social learning situation for action memory in seventy-six 4-year-old children and tested if source monitoring errors explain potential sleep effects (preregistration doi: 10.17605/OSF.IO/QSD2E). We employed a mixed-design combining an experimental within-subject manipulation of social interaction (high-vs.-low-collaboration condition) with an observational component measuring latency to nighttime sleep onset at T1. At T1, children participated in a social learning task scheduled at different times across the day to vary the interval between encoding and nighttime onset. Immediately following the task at T1, and again two weeks later, children's memory for which actions had been performed (action memory) and who had performed them (agent memory, as an indicator of source memory) was assessed behaviorally. Sleeping behavior and the latency to nighttime sleep was assessed using actigraphy. Contrary to expectations, both action and agent memory were unrelated to latency to nighttime sleep onset after social learning and, in exploratory analyses, to sleep efficiency and sleep duration in the night following learning. Methodological aspects including the retention interval and task difficulty might have contributed to the unexpected results.