Early childhood naps initiate emotional memory processing in preparation for enhanced overnight consolidation.

Early childhood naps support emotional memory, but benefits are only observed after overnight sleep. Whether emotional memory consolidation occurs during naps, or whether napping only prepares memories for overnight consolidation is unknown. We investigated whether naps protect emotional memories from interference, indicating consolidation. Between 2018 and 2020, 63 children in western Massachusetts preschools (30 female, 33 male; 33-67 months; 23.8% Hispanic, 87.3% White) learned faces paired with negative or neutral descriptions, followed by nap or wake. Before delayed recognition, half completed an interference task. Without interference, napping benefited recognition. With interference, children recognized fewer negative faces post-nap (compared to wake), with overnight sleep attenuating this difference. Results suggest that naps initially destabilize emotional memories, possibly reflecting partial processing that promotes long-term consolidation.

Associations of activity, sedentary, and sleep behaviors with cognitive and social-emotional health in early childhood.

Background: Early childhood is important for cognitive and social-emotional development, and a time in which to promote healthy movement behaviors (sedentary behavior, physical activity, and sleep). Movement behaviors may have interactive influences on cognition and social-emotional factors in young children, but most previous research has explored them independently. The purpose of this study was to determine if movement behaviors are associated with measures of cognitive and social-emotional health in young children and if so, to describe optimal compositions of movement behaviors of a daily cycle for such outcomes. Methods: Children (n = 388, 33 to 70 months, 44.6% female) from a clinical trial (ClinicalTrials.gov ID: NCT03285880, first posted September 18, 2017) wore accelerometers on their wrists for 24-h for 9.56 ± 3.3 days. Movement behavior compositions consisted of time spent in sedentary behaviors, light intensity physical activity, moderate to vigorous intensity physical activity (MVPA), and sleep. Outcomes were cognitive (receptive vocabulary, declarative and procedural memory, and executive attention) and social-emotional measures (temperament and behavioral problems). Compositional linear regression models with isometric log ratios were used to investigate the relations between the movement behavior composition and the cognitive and social-emotional health measures. If a significant association was found between the composition and an outcome, we further explored the "optimal" 24-h time-use for said outcome. Results: Movement behavior compositions were associated with receptive vocabulary. The composition associated with the predicted top five percent of vocabulary scores consisted of 12.1 h of sleep, 4.7 h of sedentary time, 5.6 h of light physical activity, and 1.7 h of MVPA. Conclusions: While behavior compositions are related to vocabulary ability in early childhood, our findings align with the inconclusiveness of the current evidence regarding other developmental outcomes. Future research exploring activities within these four movement behaviors, that are meaningful to cognitive and social-emotional development, may be warranted. Supplementary Information: The online version contains supplementary material available at 10.1186/s44167-023-00016-6.

Temporal Associations between Actigraphy-Measured Daytime Movement Behaviors and Nap Sleep in Early Childhood.

The purpose of this micro-longitudinal study was to explore daily associations between daytime movement behaviors (sedentary time and physical activity) and nap sleep in young children. In 298 children (age = 51.0 ± 9.6 months, 43.6% female), wrist-based actigraphy (mean wear time = 10 days) assessed sedentary time, total physical activity, and provided an estimate of nap sleep duration and efficiency. Multilevel logistic and linear regression models were used to examine temporal within-person relations between wake behaviors and nap sleep, and adjusted for overnight sleep duration between days of interest, age, sex, and socioeconomic status. Movement behaviors were not related to the likelihood of next-day napping, but when children were less sedentary (OR = 0.96; p < 0.001) or more active (OR = 1.01; p = 0.001) in the morning, they were more likely to nap that same day. Movement behaviors were not associated with nap sleep duration or efficiency. Conversely, on days children napped, they were less sedentary (B = -2.09, p < 0.001) and more active (B = 25.8, p < 0.001) the following day. Though napping and movement behaviors had some reciprocal relations, effect sizes in the present study were small. Further studies should examine children with more diverse sleep health and from different childcare settings.

Temporal relationships between device-derived sedentary behavior, physical activity, and sleep in early childhood.

STUDY OBJECTIVES: Understanding the ideal composition of a child's day requires a better understanding of the relations between wake behaviors (sedentary behavior [SB], physical activity [PA]) and sleep. Here, we examine between- and within-person temporal associations between daytime wake behaviors and overnight sleep in early childhood, an important age when healthy behaviors are initiated and 24-hour behaviors are largely determined by caregivers. METHODS: Daily, repeated measures of wake behavior and overnight sleep were assessed via wrist-worn actigraphy (mean = 9 days/nights) in 240 children (50.8 ± 9.8 months). Multilevel models with lagged effects were used to examine the temporal associations between wake and overnight sleep measures and adjusted for daily nap duration, age, sex, and socioeconomic status. RESULTS: Between-person associations for sleep outcomes were negative between moderate-to vigorous-intensity PA (MVPA) and total activity for sleep efficiency (SE). Between-person associations for wake outcomes were positive between sleep duration and light PA, and negative between SE and both MVPA and total PA. When children obtained higher SE relative to their individual average, they were more likely to engage in less SB and greater MVPA and total PA the next day. CONCLUSIONS: Generally, days with greater activity or sleep were not associated with greater subsequent sleep or PA. Most subsequent behaviors were not influenced by children achieving higher activity or sleep relative to their individual average levels, although higher SE was beneficially associated with next day wake behaviors. Future analyses with young children should consider within-person associations and could investigate lagged effects beyond one day.

Sleep and Coping in Early Childhood During the COVID-19 Pandemic.

Sleep disturbances in early childhood are associated with mood and anxiety disorders. Children also exhibit sleep disruptions, such as nighttime awakenings, nightmares, and difficulties falling asleep, in conjunction with adverse events and stress. Prior studies have examined independently the role of sleep on adaptive processing, as well as the effects of stress on sleep. However, how childhood sleep and children's adaptive behavior (i.e., coping strategies) bidirectionally interact is currently less known. Using a within-subjects design and actigraphy-measured sleep from 16 preschool-aged children (Mage = 56.4 months, SD = 10.8, range: 36-70 months), this study investigated how prior sleep patterns relate to children's coping during a potentially stressful event, the COVID-19 pandemic, and how prior coping skills may influence children's sleep during the pandemic. Children who woke earlier had greater negative expression both before and during the pandemic. During the pandemic, children slept longer and woke later on average compared to before the pandemic. Additionally, for children engaged in at-home learning, sleeping longer was associated with less negative expression. These findings highlight how sleep behaviors and coping strategies are related, and the stability of this relationship under stress.

Bedsharing in Early Childhood: Frequency, Partner Characteristics, and Relations to Sleep.

Bedsharing (sharing a bed with others during sleep) in early childhood (3-5 years old) is common across Western and non-Western societies alike. Though prior work indicates that bedsharing may relate to impairments in child sleep quantity or quality, the majority of studies conducted in young children are limited to parent-child bedsharing and rely almost exclusively on caregiver reports to measure child sleep. Here, the authors endeavored to gain further insights into the diversity of bedsharing practices among children in the United States, including how different bedsharing partners (caregivers, siblings) might impact actigraphy-derived measures of children's sleep. Using a sample of 631 children ages 2:9 to 5:11 years, we found that over 36% of children bedshared in some form overnight, with approximately 22% bedsharing habitually. In a subset of children for whom actigraphy measures were collected (n = 337), children who bedshared habitually (n = 80) had significantly shorter overnight sleep, later sleep and wake times, and longer naps than solitary sleepers (n = 257), even when controlling for socioeconomic status. Despite supplementing their shorter overnight sleep with longer naps, habitually bedsharing children had significantly shorter 24-hr sleep time than did solitary sleepers, though differences in sleep efficiency were nonsignificant for all sleep periods. Additionally, sleep efficiency, onset latency, and duration did not differ between children who habitually bedshared with siblings versus those who habitually bedshared with parents. The present results add to prior work examining family contextual correlates of sleep differences in early childhood and provide a more objective account of relations between bedsharing and child sleep.

Unhealthy Diet Is Associated With Poor Sleep in Preschool-Aged Children.

Unhealthy dietary choices are associated with poor sleep in children through adults. Yet, how diet and sleep are related in early childhood, when diet is reliant on parent choices around food availability, is unknown. The authors aimed to explore how frequency of fruit, vegetable, fast food, and soda consumption are associated with preschool children's sleep quality. They also considered how parenting factors may impact the relationship between children's sleep and diet. Actigraphy data were collected from 383 children 33-70 months old. Caregivers reported on child food and beverage frequency, demographics, and health items. Parenting strategies were assessed using the Parenting Scale. Multiple linear regression was used to examine associations between sleep and dietary measures with socioeconomic status, race-ethnicity, physical activity, and body mass index as covariates. Shorter nap duration was associated with more frequent consumption of fruits and vegetables (B = -3.6, p = .03). Shorter nighttime and 24-hr sleep durations were associated with more frequent consumption of fast food (B = -6.5, p = .01; B = -5.8, p = .01). Shorter nighttime sleep and later sleep onset were associated with more frequent soda consumption (B = -9.2, p = .01; B = 0.23, p = .001). Use of ineffective parenting strategies was negatively associated with fruit and vegetable consumption (r = -.29, p = .01) and positively associated with soda consumption (r = .25, p = .02) but was unrelated to sleep measures. Thus, ineffective parenting strategies may underlie child access to unhealthy foods, which, in turn, contributes to poor sleep. Encouraging healthier dietary habits and educating caregivers on how to reinforce such practices may lead to better sleep outcomes in early childhood.