How Preschoolers Spend Their Days Shapes Growing Minds, Canadian Study Finds

A young child’s day is a fixed budget of twenty-four hours, and every minute spent sleeping, sitting, or running around must come from somewhere. A new Canadian study has taken that zero-sum reality seriously, asking whether the way preschoolers divide their day among sleep, sedentary behaviour, light physical activity, and moderate-to-vigorous physical activity is linked to two cornerstone cognitive skills: inhibition and working memory. The findings, drawn from hundreds of children across the country, paint a picture that is both intriguing and cautiously modest about how much a child’s daily movement mix actually matters for the developing brain.

The research forms part of the SUNRISE International Study of Movement Behaviours in the Early Years, a global effort to understand how young children around the world accumulate movement and rest. In the Canadian arm, published in the Journal of Activity, Sedentary and Sleep Behaviors, researchers analysed data from 654 preschoolers with an average age of about forty-seven months, roughly fifty-three percent of whom were boys. Families and childcare centres from across Canada participated, and the study received funding from the Canadian Institutes of Health Research.

What sets this study apart methodologically is its use of compositional data analysis, a statistical framework designed for data that are inherently constrained to sum to a constant. Traditional analyses often examine each behaviour in isolation, asking, for instance, whether more sleep predicts better memory while ignoring the fact that extra sleep must necessarily displace some other behaviour. Compositional approaches treat the full twenty-four-hour day as an interdependent system, expressing each behaviour’s share relative to the others through isometric log ratio transformations before testing associations with outcomes.

The measurement of behaviour was equally rigorous. Each child wore a waist-mounted ActiGraph wGT3X+ accelerometer for seven consecutive days, providing an objective record of how much time was spent asleep, sedentary, or moving at light and moderate-to-vigorous intensities. Cognitive abilities were assessed with validated Early Years Toolbox tasks delivered on iPads, which measure inhibition, the capacity to suppress impulses and automatic responses, and working memory, the mental workspace that holds and manipulates information over short periods. Both skills are considered foundational for school readiness and later academic achievement.

In unadjusted statistical models, the overall composition of movement behaviours was significantly associated with both inhibition and working memory, although the amount of variance explained was small, with R-squared values of 0.03 for inhibition and 0.02 for working memory. However, once the researchers accounted for covariates such as demographic characteristics, those associations were no longer statistically significant. This pattern suggests that while movement behaviours may relate to cognition, the magnitude of any effect in preschool years is likely small and partly entangled with other family and child factors.

The compositional substitution analyses offered a more granular view. These models estimate what would happen to a cognitive outcome if one behaviour were swapped for another while the rest of the day stayed constant. One notable finding emerged: replacing light physical activity with sedentary time was associated with better inhibition. In other words, in this dataset, shifting a young child from gentle movement into sedentary pursuits appeared linked to slightly stronger impulse control, a counterintuitive result the authors flag as a point for future investigation rather than a prescription.

Perhaps the most eye-catching results came from the so-called Goldilocks analysis, a technique that searches for the daily allocation of the four behaviours associated with the best cognitive outcomes. For inhibition, the optimal day included about 118 minutes of moderate-to-vigorous physical activity, 726 minutes of sleep, 258 minutes of light activity, and 337 minutes of sedentary time. For working memory, the optimum shifted to roughly 164 minutes of moderate-to-vigorous activity, 664 minutes of sleep, 323 minutes of light activity, and 288 minutes of sedentary time.

Those numbers carry a striking implication when set against current guidance. The sleep values associated with optimal cognition fell comfortably within existing twenty-four-hour movement guidelines for preschoolers, reinforcing sleep as the one behaviour where current recommendations and this study’s optimal profile align. But the optimal amounts of moderate-to-vigorous physical activity exceeded current recommendations by one to two hours, suggesting, on the surface, that preschoolers might benefit cognitively from roughly double the recommended dose of energetic play. The authors themselves urge caution, noting that more work is needed before such targets could be promoted with confidence.

Another strength of the study was its attention to demographic subgroups. Previous compositional studies have largely ignored whether associations differ between three- and four-year-olds, between boys and girls, or between children in urban and rural settings. When the Canadian team ran their models separately for these groups, no significant reallocation effects emerged in any subgroup, indicating that the overall pattern of weak, composition-level associations holds broadly rather than being driven by a particular slice of the preschool population.

The authors are careful about what these findings can and cannot support. Movement behaviours, they conclude, may play a role in preschool cognitive development, but the effect is likely small, and the adjusted models remind us that many other influences shape how a four-year-old’s mind matures. Still, the study provides a useful benchmark for researchers worldwide, offering concrete estimates of optimal daily activity and sleep patterns against which future work can be compared. For parents, the practical takeaway is reassuring rather than radical: protect good sleep, encourage plenty of active play, and keep sedentary time modest, while remembering that a child’s growing brain depends on far more than the clock-time ledger of a single day.

Subject of Research: Associations between 24-hour movement behaviours and cognitive development in preschoolers

Article Title: Compositional data analysis of the associations among 24-hour movement behaviours and cognitive development of preschoolers across Canada: a SUNRISE study

Article References: Buchanan, S., Boyd, M., Bremer, E., Bruijns, B. A., Caldwell, H. A. T., Carson, V., Faulkner, G., Harandian, K., Hawthorne, M., Kuzik, N., Martins, R., Pagani, L., Potter, M., Tucker, P., & Tremblay, M. S. (2026). Compositional data analysis of the associations among 24-hour movement behaviours and cognitive development of preschoolers across Canada: a SUNRISE study. Journal of Activity, Sedentary and Sleep Behaviors. https://doi.org/10.1186/s44167-026-00115-0

Image Credits: AI Generated

DOI: 10.1186/s44167-026-00115-0

Keywords: preschoolers, cognitive development, working memory, inhibition, physical activity, sedentary behaviour, sleep, compositional data analysis, accelerometers, SUNRISE study, movement behaviours, 24-hour guidelines