The contribution of good sleep to working memory in preschool: A matter of sleep quality or duration?

Actigraphy-assessed sleep duration and quality and executive function in a sample of typically developing preschoolers

Sleep is essential for cognitive development and brain maturation during early childhood. Studies focused on preschool populations using objective measures of sleep are still scarce. The objective of this study was to examine the associations between objective measures of sleep duration and quality with executive functioning in a 133 non-clinical sample of Spanish participants (Mage = 60.33 months, SD = 9.04; ages 41-77 months; 51.1% girls). Sleep was assessed for five weeknights using actigraphy; Shape School task was applied to assess inhibition and cognitive flexibility; and Word Span task was used to assess working memory. The results revealed that relation between sleep and executive functioning was significant for inhibition and working memory. Preschoolers with higher sleep efficiency showed better results in executive functioning tasks after controlling for the effect of age. Additionally, age and sleep duration and quality variables were predictive of inhibition, working memory, and cognitive flexibility. These results suggest that the different dimensions of sleep could play an important role in the development of executive functions during preschool age. Therefore, improving sleep could lead to an improvement in children's executive functioning in both clinical and educational contexts.

24-hour movement behaviors and cognitive ability in preschool children: A compositional and isotemporal reallocation analysis

Research has supported the association between movement behaviors and cognitive ability in preschool children. However, most of the research has independently examined the various movement behaviors (e.g., physical activity, sedentary behavior, and sleep) without considering the dynamic composition of these behaviors in a 24-hour daily cycle. Therefore, this study aimed to explore the relationship between 24-hour movement behaviors and cognitive ability in preschool children. The participants were 191 Chinese preschool children from Zhuzhou aged 3-6 years. We measured light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and sedentary behavior (SB) using the Actigraph Accelerometers and evaluated the children's sleep time based on reports from parents and teachers. The Chinese version of the Wechsler Young Children Scale of Intelligence (C-WYCSI) was used to assess cognitive ability. Compositional analysis and isotemporal substitution were performed to examine the influence of 24-hour movement behaviors on children's cognitive ability. After controlling for demographics (e.g., age and sex), the composition of 24-hour movement behaviors was significantly associated with the verbal intelligence quotient (VIQ), performance intelligence quotient (PIQ), and full intelligence quotient (FIQ). Importantly, preschool children demonstrated greater cognitive behavior when time in MVPA replaced that spent in LPA, SB, or sleep than when time spent in LPA, SB, and sleep replaced that spent in MVPA within the 24-hour cycle. Physical activity engaged in a 24-hour daily cycle has a significant effect on cognitive ability in preschool children, with increased MVPA and LPA being associated with higher PIQ and FIQ and increased sleep being associated with lower VIQ, PIQ, and FIQ. Replacing time in SB and LPA with MVPA is promising for children's cognitive development.

Autobiographical memory specificity and objective sleep quality: the role of preschool stress

Autobiographical memory specificity and sleep undergo significant changes across the preschool years. This study sought to examine the association between actigraphy-measured sleep quality and autobiographical memory specificity in preschoolers. Additionally, we analyzed the mediating role of sleep in the relationship between stress and autobiographical memory. The sample comprised 67 participants (Mage = 60.39 months, SD = 9.25). To measure the study variables, we used the Autobiographical Memory Test-Preschoolers, wGT3X-BT actigraphs, an ad hoc healthy sleep questionnaire, and the Children's Daily Stress Inventory. Total sleep duration and sleep efficiency were found to be positively related to autobiographical specificity. Furthermore, the participants adhering to recommendations on sleep showed higher levels of specificity compared to those whose sleep patterns were inappropriate. The negative impact of stress on specific memory increased when the indirect effects of poorer sleep duration and efficiency were included, suggesting a moderated mediation effect, where sleep moderates the relationship between stress and specific memory. These findings could have significant implications for preschoolers' cognitive development and mental health, highlighting the role of sleep and stress in influencing memory and emotional well-being.

Evaluation of the association between excessive screen use, sleep patterns and behavioral and cognitive aspects in preschool population. A systematic review

In this review, we analyzed the possible relationship between the excessive use of screens and sleep patterns, and how this may affect certain behavioral and cognitive factors in preschool children. The selection, extraction and synthesis of the data were conducted according to PRISMA guidelines. The search was carried out in the electronic databases Medline (PubMed), PsycINFO (American Psychological Association), Scopus and Web of Science (WOS). Of the 597 articles initially identified, 13 met the inclusion criteria. The risk of bias of the articles selected was evaluated using a specific scale created for this purpose. The results found indicate that excessive use of screens is associated with a negative impact on the duration and quality of sleep-in preschoolers, and this worsening of sleep in infancy is related with a greater probability of the appearance of internalizing and externalizing behavioral problems and certain cognitive problems. The results also suggest that sleep could play a mediating or moderating role as a bioregulatory system that attenuates or increases the onset of behavioral and cognitive difficulties in those children most exposed to digital devices.