A recent study published in Nutrients examined how sleep duration and yogurt intake during infancy may influence working memory (WM) in children at age four. Working memory, an early-developing component of executive function, is essential for higher-order cognitive tasks and gradually improves from infancy through preschool years. Sleep is known to support brain development and cognitive performance, while dietary factors, such as yogurt consumption, may impact cognition via the gut–brain axis.
The study analyzed 164 mother–child pairs from the Kyoto Regional Centre of the Japan Environment and Children’s Study. Sleep patterns were assessed at ages 1, 1.5, and 3 years, and yogurt intake was reported at age 1. At age four, children completed a digit span task from the Kyoto Scale of Psychological Development to evaluate verbal working memory. Additional information, including parental education and household income, was also collected.
Results indicated significant variability in sleep and dietary habits among children. Nighttime sleep at age one positively correlated with verbal WM at age four, suggesting longer night sleep in infancy supports memory development. Daytime or total sleep duration at any age showed no significant association, although a marginal link was observed between total sleep at age three and later WM. Yogurt intake at age one was significantly associated with higher verbal WM scores at age four. Hierarchical regression analysis suggested that early yogurt consumption had a stronger predictive value for WM than night sleep duration.
These findings suggest that early-life nutrition and sleep patterns may contribute to the development of working memory, with yogurt intake showing particular relevance. While the observed effects were modest, the study underscores the importance of early dietary habits alongside sleep for cognitive outcomes. Future research with larger and more diverse cohorts is needed to validate these associations and explore mechanisms linking gut health, sleep, and memory development in early childhood.
