Cognitive benefits of last night's sleep: daily variations in children's sleep behavior are related to working memory fluctuations

Change-point detection using diffusion maps for sleep apnea monitoring with contact-free sensors

Monitoring and improving the quality of sleep are crucial from a public health perspective. In this study, we propose a change-point detection method using diffusion maps for a more accurate detection of respiratory arrest points. Conventional change-point detection methods are limited when dealing with complex nonlinear data structures, and the proposed method overcomes these limitations. The proposed method embeds subsequence data in a low-dimensional space while considering the global and local structures of the data and uses the distance between the data as the score of the change point. Experiments using synthetic and real-world contact-free sensor data confirmed the superiority of the proposed method when dealing with noise, and it detected apnea events with greater accuracy than conventional methods. In addition to improving sleep monitoring, the proposed method can be applied in other fields, such as healthcare, manufacturing, and finance. This study will contribute to the development of advanced monitoring systems that adapt to diverse conditions while protecting privacy.

Interindividual Differences in Cognitive Variability Are Ubiquitous and Distinct From Mean Performance in a Battery of Eleven Tasks

Our performance on cognitive tasks fluctuates: the same individual completing the same task will differ in their response's moment-to-moment. For decades cognitive fluctuations have been implicitly ignored - treated as measurement error - with a focus instead on aggregates such as mean performance. Leveraging dense trial-by-trial data and novel time-series methods we explored variability as an intrinsically important phenotype. Across eleven cognitive tasks with over 7 million trials, we found highly reliable interindividual differences in cognitive variability in every task we examined. These differences are both qualitatively and quantitatively distinct from mean performance. Moreover, we found that a single dimension for variability across tasks was inadequate, demonstrating that previously posited global mechanisms for cognitive variability are at least partially incomplete. Our findings indicate that variability is a fundamental part of cognition - with the potential to offer novel insights into developmental processes.

Characteristics of sleep in children with heavy prenatal alcohol exposure

BACKGROUND

Sleep plays an important role in neurodevelopment. However, the effects of prenatal alcohol exposure on sleep quality have been understudied, despite reports of sleep disturbance in infants prenatally exposed to alcohol and elevated levels of sleep problems reported by caregivers of children with fetal alcohol spectrum disorders. The current study characterizes sleep in children with prenatal alcohol exposure using both objective (actigraphy) and subjective (questionnaires, sleep diaries) methods.

METHODS

Participants aged 6-10 years, with and without prenatal alcohol exposure, were included in the study (alcohol-exposed [AE]: n = 35; control [CON]: n = 39). Objective sleep was measured via 24-h actigraphy for 2 weeks. Parents completed sleep diaries and sleep questionnaires (Children's Sleep Habits Questionnaire, Pediatric Sleep Questionnaire). Multivariate analysis of variance was used to characterize the sleep profile (objective, subjective) and examine group differences.

RESULTS

There were no group differences on actigraphy metrics averaged across 2 weeks. However, the AE group showed significantly greater intraindividual variability on most actigraphy measures, particularly total sleep time, percent sleep, wake after sleep onset, and number of wake bouts. Parents reported significantly more sleep problems in the AE group than in the CON group, primarily driven by night wakings, parasomnias (e.g., sleepwalking), snoring, and daytime sleepiness. These effects were more severe in children >8.5 years of age.

CONCLUSIONS

Despite similar 2-week average sleep outcomes, children with prenatal alcohol exposure showed greater intraindividual sleep variability and parents reported more sleep problems related to sleep behavior and snoring. These difficulties with sleep may be related to other cognitive and behavioral outcomes. Importantly, sleep is a modifiable behavior, and interventions that focus on variability in sleep, particularly in sleep duration, can impact the quality of life in children with prenatal alcohol exposure and their families.

When experiencing nice interactions at work: Good sleep quality via well-being

Based on the Work-Home Resources Model and Conservation of Resources Theory, we develop dual mechanisms by which nice interactions (patients' compliments and coworkers' informational support) predict sleep quality. Specifically, we expect these nice interactions to help individuals conserve their personal energy in the form of less cognitive depletion (a cognitive process) and diminished physical fatigue (a physical process). Further, we propose employees utilise their energy resources to experience better sleep quality. To test the proposed model, we utilised an experience-sampling method by recruiting 223 female nurses working in a regional university hospital in South Korea. Specifically, we measured nice interactions and personal resources at 3 PM on Day t and sleep quality at 5-6 AM on Day t + 1, and we administered the questionnaire for 10 consecutive days. Overall, after removing 79 invalid observations (not completing questionnaire in a timely manner), we had a final total of two-wave 1997 daily observations from 223 nurses. Receiving more compliments from patients and more information from coworkers positively affects nurses' cognitive energy (less cognitive depletion) and physical energy (less physical fatigue), which predicts better sleep quality. Finally, results supported indirect effects of these nice interactions on sleep quality via cognitive and physical processes.

State-level working memory and dysregulated eating in children and adolescents: An exploratory ecological momentary assessment study

BACKGROUND

Children with loss of control (LOC) eating and overweight/obesity have relative deficiencies in trait-level working memory (WM), which may limit adaptive responding to intra- and extra-personal cues related to eating. Understanding of how WM performance relates to eating behavior in real-time is currently limited.

METHODS

We studied 32 youth (ages 10-17 years) with LOC eating and overweight/obesity (LOC-OW; n = 9), overweight/obesity only (OW; n = 16), and non-overweight status (NW; n = 7). Youth completed spatial and numerical WM tasks requiring varying degrees of cognitive effort and reported on their eating behavior daily for 14 days via smartphone-based ecological momentary assessment. Linear mixed effects models estimated group-level differences in WM performance, as well as associations between contemporaneously completed measures of WM and dysregulated eating.

RESULTS

LOC-OW were less accurate on numerical WM tasks compared to OW and NW (ps < .01); groups did not differ on spatial task accuracy (p = .41). Adjusting for between-subject effects (reflecting differences between individuals in their mean WM performance and its association with eating behavior), within-subject effects (reflecting variations in moment-to-moment associations) revealed that more accurate responding on the less demanding numerical WM task, compared to one's own average, was associated with greater overeating severity across the full sample (p = .013). There were no associations between WM performance and LOC eating severity (ps > .05).

CONCLUSIONS

Youth with LOC eating and overweight/obesity demonstrated difficulties mentally retaining and manipulating numerical information in daily life, replicating prior laboratory-based research. Overeating may be related to improved WM, regardless of LOC status, but temporality and causality should be further explored.

PUBLIC SIGNIFICANCE STATEMENT

Our findings suggest that youth with loss of control eating and overweight/obesity may experience difficulties mentally retaining and manipulating numerical information in daily life relative to their peers with overweight/obesity and normal-weight status, which may contribute to the maintenance of dysregulated eating and/or elevated body weight. However, it is unclear whether these individual differences are related to eating behavior on a moment-to-moment basis.

Mediterranean diet, physical activity, and family characteristics associated with cognitive performance in Italian primary school children: analysis of the I-MOVE project

Working memory (WM) is a multicomponent system that supports cognitive functioning. It has been linked to a wide variety of outcomes including academic success and general well-being. The present study examined the relations between adherence to the Mediterranean diet (MD) and WM among Italian children, adjusting for important parent characteristics and children's lifestyle habits. Data for this study was obtained from 106 children attending primary school in Imola (Italy) who were part of the I-MOVE study emphasizing school-based physical activity. Children's adherence to the MD was calculated using the KIDMED index (KI) based on the ZOOM-8 questionnaire. Physical activity (PA) levels were assessed using an actigraph accelerometer and WM using the backward digit span test. Univariate regression was used to select significant child-level and family measures associated with WM, which were then tested in a single multivariate regression model. Older age is positively associated with higher WM (β = 0.36; 95% CI 0.25, 0.47). Dietary adherence (KI) (β = 0.07; 95% CI 0.01, 0.14) and engagement in organized PA outside school hours (β = 0.58; 95% CI 0.09, 1.10) are positively related to WM. Among the family measures, father's education was positively associated with WM for high school education and for university vs. middle school or lower, respectively.

CONCLUSION

Adherence to the MD was associated with better WM capacity in primary school children. These findings can be used to guide policymakers in designing health promotion programs and instituting policies emphasizing healthy nutrition to improve physical health and boost cognitive functioning.

WHAT IS KNOWN

• The development of working memory involves the entire childhood with a rapid spurt between 2 and 8 years of age. • Working memory plays a critical role in children's learning and academic performance and underlies higher-order cognitive abilities.

WHAT IS NEW

• Adherence to the Mediterranean Diet was associated with higher working memory capacity in primary school children. • Health promotion interventions based on PA and sound nutrition involving children benefit not only physical and mental health, but also cognitive health.

A developmental perspective on sleep consistency: Preschool age through emerging adulthood

OBJECTIVE/BACKGROUND

Beyond sleep duration, the regularity of sleep patterns (e.g., sleep consistency), including variability in sleep timing (e.g., bedtime, wake time) and duration, is a critical marker of sleep health. Sleep consistency is captured using a variety of methods within the literature (e.g., sleep intraindividual variability, social jetlag), but most of the research focuses on adolescents.

METHODS

Drawing on a developmental perspective, this narrative review highlights how normative changes at the individual (e.g., biological, cognitive, and social) and contextual (e.g., home, school, sociocultural) levels may contribute to inconsistent sleep patterns across development.

RESULTS AND CONCLUSIONS

This review emphasizes how inconsistent sleep may increase across pivotal transitions throughout development (e.g., elimination of naps, puberty, summertime, entering college). Finally, recommendations for measuring sleep consistency and areas to address in future research are discussed.

Clinical and psychological status analysis of children and parents infected with familial aggregation omicron variant in Shanghai in parent-child ward

Aims

To analyze the clinical characteristics, treatment outcomes and sleep psychological problems of children and parents infected with familial aggregation Omicron variants under a parent-child ward treatment mode to provide a theoretical reference for the diagnosis and comprehensive treatment of Omicron variant strains.

Methods

The clinical data of 225 children and 230 adult family members admitted were retrospectively collected and analyzed to investigate their clinical characteristics and response to treatments.

Results

The proportion of infected adults and children was the same, and the proportion of children with mild disease was higher than that of adults, but the clinical symptoms were milder. The clinical symptoms of fever, nausea, vomiting and wheezing in children were significantly higher than in adults (P < 0.05). In addition, dry pharynx, pharynx itching and pharyngeal pain were lower than in adults (P < 0.05). The time of turning negative in the moderate group was longer than in the mild group, and the time of turning negative in the unvaccinated group was higher than in the vaccinated group (P < 0.05). The Cycle Threshold Value (Ct value) of Open Reading Frame 1ab (ORF1ab) and Nucleocapsid protein (N) gene of children were higher adults. The increase in the rate of Ct value of ORF1ab and N gene in adults treated with Traditional Chinese Medicine (TCM) was significantly higher than in those who underwent symptomatic treatment (P < 0.01). Based on the Children's Sleep Habits Questionnaire (CSHQ)score, we found varying levels of sleep problems in sleeping habits, latency and anxiety, night awakenings and abnormal sleep at all ages (P < 0.05). In the adult group, those with Self-Rating Scale of Sleep (SRSS) scores ≥3 accounted for more than 50% of adults with insomnia, sleep deprivation, sleep instability and early awakening. The proportion of adults with anxiety and depression was 21.3% and 16.4%.

Conclusion

Infections in children and adults during this pandemic were mainly associated with familial aggregation infections, and their clinical symptoms were mainly located in the upper respiratory tract. With comprehensive treatment, children became negative faster, vaccination led to faster recovery, and although some patients experienced sleeping and psychological issues, all patients had good prognoses following comprehensive diagnosis under a parent-child ward treatment mode.

Mechanisms of processing speed training and transfer effects across the adult lifespan: protocol of a multi-site cognitive training study

Background

In recent years, cognitive training has gained popularity as a cost-effective and accessible intervention aiming at compensating for or even counteracting age-related cognitive declines during adulthood. Whereas the evidence for the effectiveness of cognitive training in general is inconsistent, processing speed training has been a notable successful exception, showing promising generalized benefits in untrained tasks and everyday cognitive functioning. The goal of this study is to investigate why and when processing speed training can lead to transfer across the adult lifespan. Specifically, we will test (1) whether training-induced changes in the rate of evidence accumulation underpin transfer to cognitive performance in untrained contexts, and (2) whether these transfer effects increase with stronger attentional control demands of the training tasks.

Methods

We will employ a multi-site, longitudinal, double-blinded and actively controlled study design with a target sample size of N = 400 adult participants between 18 and 85 years old. Participants will be randomly assigned to one of three processing speed training interventions with varying attentional control demands (choice reaction time, switching, or dual tasks) which will be compared to an active control group training simple reaction time tasks with minimal attentional control demands. All groups will complete 10 home-based training sessions comprising three tasks. Training gains, near transfer to the untrained tasks of the other groups, and far transfer to working memory, inhibitory control, reasoning, and everyday cognitive functioning will be assessed in the laboratory directly before, immediately after, and three months after training (i.e., pretest, posttest, and follow-up, respectively). We will estimate the rate of evidence accumulation (drift rate) with diffusion modeling and conduct latent-change score modeling for hypothesis testing.

Discussion

This study will contribute to identifying the cognitive processes that change when training speeded tasks with varying attentional control demands across the adult lifespan. A better understanding of how processing speed training affects specific cognitive mechanisms will enable researchers to maximize the effectiveness of cognitive training in producing broad transfer to psychologically meaningful everyday life outcomes.

Trial registration Open Science Framework Registries, registration https://doi.org/10.17605/OSF.IO/J5G7E; date of registration: 9 May 2022.

The CLASS Study (Circadian Light in Adolescence, Sleep and School): protocol for a prospective, longitudinal cohort to assess sleep, light, circadian timing and academic performance in adolescence

BACKGROUND

During adolescence, sleep and circadian timing shift later, contributing to restricted sleep duration and irregular sleep-wake patterns. The association of these developmental changes in sleep and circadian timing with cognitive functioning, and consequently academic outcomes, has not been examined prospectively. The role of ambient light exposure in these developmental changes is also not well understood. Here, we describe the protocol for the Circadian Light in Adolescence, Sleep and School (CLASS) Study that will use a longitudinal design to examine the associations of sleep-wake timing, circadian timing and light exposure with academic performance and sleepiness during a critical stage of development. We also describe protocol adaptations to enable remote data collection when required during the COVID-19 pandemic.

METHODS

Approximately 220 healthy adolescents aged 12-13 years (school Year 7) will be recruited from the general community in Melbourne, Australia. Participants will be monitored at five 6 monthly time points over 2 years. Sleep and light exposure will be assessed for 2 weeks during the school term, every 6 months, along with self-report questionnaires of daytime sleepiness. Circadian phase will be measured via dim light melatonin onset once each year. Academic performance will be measured via national standardised testing (National Assessment Program-Literacy and Numeracy) and the Wechsler Individual Achievement Test-Australian and New Zealand Standardised Third Edition in school Years 7 and 9. Secondary outcomes, including symptoms of depression, anxiety and sleep disorders, will be measured via questionnaires.

DISCUSSION

The CLASS Study will enable a comprehensive longitudinal assessment of changes in sleep-wake timing, circadian phase, light exposure and academic performance across a key developmental stage in adolescence. Findings may inform policies and intervention strategies for secondary school-aged adolescents.

ETHICS AND DISSEMINATION

Ethical approval was obtained by the Monash University Human Research Ethics Committee and the Victorian Department of Education. Dissemination plans include scientific publications, scientific conferences, via stakeholders including schools and media.

STUDY DATES

Recruitment occurred between October 2019 and September 2021, data collection from 2019 to 2023.

Indirect Associations Between Self-Rated Alertness and Recall via Strategic and Nonstrategic Factors

Excessive daytime sleepiness is associated with reduced cognitive functioning in children and adolescents. The present study was an initial examination of direct and indirect associations between sleep and recall via strategic and nonstrategic memory processes in a sample of 66 participants from grades 1, 3, 5, and college. Stimuli varied in familiarity and presence of a strategy prompt. Strategy use during encoding and during recall were measured separately. The present study predicted that alertness would be associated with both strategic and nonstrategic factors related to memory, alertness would predict recall indirectly via strategic and nonstrategic factors (controlling for grade and gender), and this indirect path would be moderated by grade. The first 2 hypotheses were partially supported; the third was not. Self-reported alertness associated weakly with speed of tapping and with strategy use during encoding on the first trial (familiar words, no strategy cue). Analysis indicated an indirect effect via strategy use during encoding on Trial 1 but via speed of tapping on Trial 3. Tests of moderated mediation were not significant on any trial, indicating that the indirect pathways were not moderated by grade. Alertness may influence recall via strategic or nonstrategic processes, and its role may depend on familiarity and availability of strategy cues. Several proposed research directions are suggested for future exploration.

The Association of Self-Reported ADHD Symptoms and Sleep in Daily Life of a General Population Sample of School Children: An Inter- and Intraindividual Perspective

Sleep and Attention-Deficit/Hyperactivity Disorder (ADHD) have repeatedly been found to be associated with each other. However, the ecological validity of daily life studies to examine the effect of sleep on ADHD symptoms is rarely made use of. In an ambulatory assessment study with measurement burst design, consisting of three bursts (each 6 months apart) of 18 days each, 70 German schoolchildren aged 10–12 years reported on their sleep quality each morning and on their subjective ADHD symptom levels as well as their sleepiness three times a day. It was hypothesized that nightly sleep quality is negatively associated with ADHD symptoms on the inter- as well as the intraindividual level. Thus, we expected children who sleep better to report higher attention and self-regulation. Additionally, sleepiness during the day was hypothesized to be positively associated with ADHD symptoms on both levels, meaning that when children are sleepier, they experience more ADHD symptoms. No association of sleep quality and ADHD symptoms between or within participants was found in multilevel analyses; also, no connection was found between ADHD symptoms and daytime sleepiness on the interindividual level. Unexpectedly, a negative association was found on the intraindividual level for ADHD symptoms and daytime sleepiness, indicating that in moments when children are sleepier during the day, they experience less ADHD symptoms. Explorative analyses showed differential links of nightly sleep quality and daytime sleepiness, with the core symptoms of inattention and hyperactivity/impulsivity, respectively. Therefore, future analyses should take the factor structure of ADHD symptoms into account.

Daily fluctuations in young children's persistence

Children's behavior changes from day to day, but the factors that contribute to its variability are understudied. We developed a novel repeated measures paradigm to study children's persistence by capitalizing on a task that children complete every day: toothbrushing (N = 81; 48% female; 36-47 months; 80% white, 14% Multiracial, 10% Hispanic, 2% Asian, 1% Black; 1195 observations collected between January 2019 and March 2020). Children brushed longer on days when their parents used more praise (d = .23) and less instruction (d = -.22). Sensitivity to mood, sleep, and parent stress varied across children, suggesting that identifying the factors that shape an individual child's persistence could lead to personalized interventions.

Brain network coupling associated with cognitive performance varies as a function of a child's environment in the ABCD study

Prior research indicates that lower resting-state functional coupling between two brain networks, lateral frontoparietal network (LFPN) and default mode network (DMN), relates to cognitive test performance, for children and adults. However, most of the research that led to this conclusion has been conducted with non-representative samples of individuals from higher-income backgrounds, and so further studies including participants from a broader range of socioeconomic backgrounds are required. Here, in a pre-registered study, we analyzed resting-state fMRI from 6839 children ages 9-10 years from the ABCD dataset. For children from households defined as being above poverty (family of 4 with income > $25,000, or family of 5+ with income > $35,000), we replicated prior findings; that is, we found that better performance on cognitive tests correlated with weaker LFPN-DMN coupling. For children from households defined as being in poverty, the direction of association was reversed, on average: better performance was instead directionally related to stronger LFPN-DMN connectivity, though there was considerable variability. Among children in households below poverty, the direction of this association was predicted in part by features of their environments, such as school type and parent-reported neighborhood safety. These results highlight the importance of including representative samples in studies of child cognitive development.

Correlations between sleep disturbance and brain cortical morphometry in healthy children

Background

While the importance of adequate sleep duration to normal brain development is well known, more studies are needed to characterize how undiagnosed sleep disturbance other than suboptimal sleep duration may impact brain development. In this study we aim to understand the relationships between sleep disturbance measures and cortical morphometry in typically-developing children without previous diagnoses of sleep pathology.

Methods

Healthy 8-year-old children (30 boys, 37 girls) without clinical diagnosis of sleep disorders were prospectively recruited for brain MRI and their parents completed the Children’s Sleep Habits Questionnaire (CSHQ). Total sleep disturbance score, as well as 8 subscales including bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night waking, parasomnias, sleep disordered breathing, and daytime sleepiness were calculated, and their relationships with cortical morphometry features including cortical gray matter volume, cortical thickness, and surface area were investigated, controlled for total cortical volume and sex.

Results

The CSHQ total sleep disturbance score significantly correlated with cortical surface area in a cluster in the left middle temporal gyrus (P < 0.001, R = -0.54). In addition, the bedtime resistance subscale negatively correlated with cortical surface area in a cluster in the right fusiform gyrus (P < 0.001, R = -0.50). No other clusters showed significant relationships between CSHQ total score or subscales and cortical features for this cohort.

Conclusion

Significant relationships between sleep disturbance scores in typically-developing children without clinical diagnosis of sleep pathology and their brain cortical surface area in two temporal lobe regions were identified, suggesting that undiagnosed sleep disturbance may potentially impact brain development even in healthy children.

Concordance between subjective and objective measures of infant sleep varies by age and maternal mood: Implications for studies of sleep and cognitive development

Infant habitual sleep has been proposed as an important moderator of development in domains such as attention, memory or temperament. To test such hypotheses, we need to know how to accurately and consistently assess habitual sleep in infancy. Common assessment methods include easy to deploy but subjective parent-report measures (diary/sleep questionnaire); or more labour-intensive but objective motor movement measures (actigraphy). Understanding the degree to which these methods provide converging insights is important, but cross-method agreement has yet to be investigated longitudinally. Moreover, it is unclear whether concordance systematically varies with infant or maternal characteristics that could represent confounders in observational studies. This longitudinal study (up to 4 study visits/participant) investigated cross-method concordance on one objective (7-day actigraphy) and three commonly used subjective (7-day sleep diary, Brief Infant Sleep Questionnaire, Sleep & Settle Questionnaire) sleep measures in 76 typically developing infants (age: 4–14 months) and assessed the impact of maternal characteristics (stress, age, education) and infant characteristics (age) on cross-method concordance. In addition, associations between objective and subjective sleep measures and a measure of general developmental status (Ages & Stages Questionnaire) were investigated. A range of equivalence analyses (tests of equivalence, correlational analyses, Bland-Altman plots) showed mixed agreement between sleep measures. Most importantly, cross-method agreement was associated with maternal stress levels and infant age. Specifically, agreement between different measures of night waking was better for mothers experiencing higher stress levels and was higher for younger than older infants; the reverse pattern was true for day sleep duration. Interestingly, objective and subjective measures did not yield the same patterns of association with developmental domains, indicating that sleep method choice can influence which associations are found between sleep and cognitive development. However, results converged across day sleep and problem-solving skills, highlighting the importance of studying day sleep in future studies. We discuss implications of sleep method choice for investigating sleep in the context of studying infant development and behaviour.

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A range of equivalence analyses showed mixed agreement between subjective and objective sleep measures.

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Cross-method agreement was associated with maternal stress levels and infant age.

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Objective and subjective measures did not yield the same patterns of association with developmental domains except for day sleep duration.

Between-person and within-person associations of sleep and working-memory in the everyday lives of old and very old adults: initial level, learning, and variability

STUDY OBJECTIVES

Sleep duration affects various aspects of cognitive performance, such as working-memory and learning, among children and adults. However, it remains open, whether similar or even stronger associations exist in old and very old age when changes in sleep and cognitive decrements are common.

METHODS

Using repeated daily-life assessments from a sample of 121 young-old (66-69 years old) and 39 old-old adults (84-90 years old), we assessed links between sleep duration and different aspects of working-memory (initial level, practice-related learning, and residualized variability) between and within persons. Participants reported their sleep durations every morning and performed a numerical working-memory updating task six times a day for seven consecutive days.

RESULTS

Both people who slept longer and those who slept shorter than the sample average showed lower initial performance levels, but a stronger increase of WM over time (i.e. larger learning effects), relative to people with average sleep. Sleep duration did not predict performance variability. Within-person associations were found for people sleeping relatively little on average: For them, working-memory performance was lower on days with shorter than average sleep, yet higher on days with longer than average sleep. Except for lower initial levels of working-memory in old-old adults, no differences between young-old and old-old adults were observed.

CONCLUSION

We conclude that sufficient sleep remains important for working-memory performance in older adults and that it is relevant to include different aspects of working-memory performance, because effects differed for initial performance and learning.

Memory for emotional images across sleep versus wake in school-aged children

Sleep is important for emotional well-being, memory, and development in children. Regarding memory, sleep has been shown to advantage accuracy for declarative tasks but not procedural tasks. There is some evidence to suggest that sleep provides a relatively greater benefit for memory of negative emotional versus neutral images. However, the extent to which sleep benefits emotionally positive memories in children is not clear. This study assessed memory after nocturnal sleep versus daytime wake in a within-person design involving a sample of 40 children aged 7 to 14 years (M = 10.6 ± 1.9 years; 18 boys and 22 girls) for images of negative, neutral, and positive valences. Results show that after accounting for response time, memory accuracy overall was greater after sleep compared with equivalent time of wake and memory accuracy was greatest for positive images compared with both negative and neutral images. However, there was no difference between memory for negative images and that for neutral images in children, and there was no condition by valence interaction. Sleep characteristics as recorded using actigraphy, diary, and parent report were not predictive of memory performance after sleep when correcting for multiple comparisons. Overall, the results suggest that sleep may benefit memory in otherwise healthy children but that despite a bias toward memory for positive items over both negative and neutral items, there is not a relatively greater benefit for emotional versus neutral memory consolidation across sleep periods compared with wake periods.

Executive Functions in Social Context: Implications for Conceptualizing, Measuring, and Supporting Developmental Trajectories

Success in life is linked to executive functions, a collection of cognitive processes that support goal-directed behaviors. Executive functions is an umbrella term related to cognitive control, self-control, and more. Variations in executive functioning predict concurrent success in schooling, relationships, and behavior, as well as important life outcomes years later. Such findings may suggest that certain individuals are destined for good executive functioning and success. However, environmental influences on executive function and development have long been recognized. Recent research in this tradition demonstrates the power of social contextual influences on children's engagement of executive functions. Such findings suggest new interpretations of why individuals differ in executive functioning and associated life outcomes, including across cultures and socioeconomic statuses. These findings raise fundamental questions about how best to conceptualize, measure, and support executive functioning across diverse contexts. Future research addressing real-world dynamics and computational mechanisms will elucidate how executive functioning emerges in the world.

Negative Emotion Differentiation Attenuates the Within-Person Indirect Effect of Daily Stress on Nightly Sleep Quality Through Calmness

The ability to differentiate between negative emotional states [negative emotion differentiation (NED)] has been conceptualized as a trait that facilitates effective emotion regulation and buffers stress reactivity. In the present research, we investigated the role of NED in within-person processes of daily affect regulation and coping during times of stress (the first COVID-19-related pandemic lockdown in April 2020). Using intensive longitudinal data, we analyzed whether daily stress had an indirect effect on sleep quality through calmness in the evening, and we tested whether NED moderated this within-person indirect effect by buffering the link between daily stress and calmness in the evening. A non-representative community sample (n = 313, 15–82 years old) participated in a 21-day ambulatory assessment with twice-daily surveys. The results of multilevel mediation models showed that higher daily stress was related to within-day change in calmness from morning to evening, resulting in less calmness in the evening within persons. Less calmness in the evening, in turn, was related to poorer nightly sleep quality within persons. As expected, higher NED predicted a less negative within-person link between daily stress and calmness in the evening, thereby attenuating the indirect effect of daily stress on nightly sleep quality through calmness. This effect held when we controlled for mean negative emotions and depression. The results provide support for a diathesis-stress model of NED, and hence, for NED as a protective factor that helps to explain why some individuals remain more resilient during times of stress than others.

PSIXPORT: Mobile App for Ecological Momentary Assessment of Psychological Dimensions in Sport Injury

Retrospective self-reports have been commonly used to assess psychological variables such as feelings, thoughts, or emotions. Nevertheless, this method presents serious limitations to gather accurate information about variables that change over time. The Ecological Momentary Assessment (EMA) approach has been used to deal with some of the limitations these retrospective assessment methods present, and for gathering real-time information about dynamic psychological variables, such as feelings, thoughts, or behaviors. In the sports injury rehabilitation context, athletes' thoughts, feelings, behaviors, and pain perceptions during the rehabilitation process can influence the outcomes of this process. These responses change over different stages of the rehabilitation and taking them into account can help therapists to adapt the rehabilitation process and increasing their effectiveness. With this aim, an EMA mobile app (PSIXPORT) was designed to gather real-time information about severely injured athletes' cognitive appraisals, emotional responses, behaviors, and pain perceptions during their rehabilitation process. The goals of this study were to evaluate Psixport's ability to gather real-time information about injured athletes' psychological responses during the rehabilitation, to test the users' perceived usability of Psixport, and to compare the reliability and differences between real-time data gathered with Psixport and the data gathered through the one-time retrospective method. Twenty-eight severely injured athletes (10 men and 18 women) were assessed using Psixport, a retrospective questionnaire, and the uMARS usability test. Results showed that Psixport can be considered as a good tool to gather information about injured athletes' cognitive appraisals, emotional responses, behaviors, and pain perceptions. Moreover, multiple data assessments gathered with the app showed to be more accurate information about injured athletes' psychological responses than one-time retrospective reports.

Sleep and self-regulation in early childhood

What is the role of sleep in children's behavioral, emotional, and cognitive regulation? This chapter considers theoretical and conceptual links between sleep and self-regulation, with special attention to sleep and self-regulation in early childhood. We selectively review the growing body of research on associations between sleep and self-regulation, mentioning some methodological issues. We also consider how child characteristics and sociocontextual factors may interact with sleep in the development of self-regulation in early childhood. We provide some relevant empirical examples from our own research.

Newly walking infants' night sleep impacts next day learning and problem solving

Sleep is part of the process that prepares children and adults for next day cognitive activity. Insufficient or fragmented sleep has a detrimental impact on subsequent encoding (Rouleau et al., 2002) and cognitive functioning (Joo et al., 2012). However, fragmented sleep early in life is a developmental norm, limiting the extent to which conclusions derived from older populations can be generalized. To directly test the continuity of this relationship, newly-walking infants' (N=58) sleep was monitored overnight using actigraphy. The next morning they were taught a motor problem-solving task. The task required infants to navigate through a tunnel to reach a goal at the other end. We coded infants' exploratory behaviors and the extent of training required to solve the task. Using a cluster analysis that accounted for exploratory behaviors and number of training prompts, infants were sorted into three profiles: those who found the task Easy to solve, those who found it Difficult, and those who Never solved it. Wake episodes and sleep efficiency were entered as predictors of cluster membership in a multinomial logistic regression. Of the infants who ultimately solved the task, those with more wake episodes and lower sleep efficiency had more difficulty. Specifically, fragmentation appeared to negatively impact preparedness to learn. Contrary to our expectations, infants who Never solved the task had the least fragmented sleep, indicating that an optimal level of fragmentation is needed for efficient problem-solving. For infants, some level of sleep fragmentation is needed the night before learning in order to solve a task efficiently. These findings highlight the interaction between developmental domains, from sleep quality to motor experience, and their impact on infant learning in real time.

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

Good sleep is essential for efficient cognitive performance. The present research examined the link between sleep and working memory (WM) during early childhood, a period of major advances in neurodevelopment. The sample included 80 healthy children, 40 3-year-olds and 40 4-year-olds, attending childcare settings. The children were individually tested using WM tasks; parents completed sleep questionnaires. On a group level, WM improved with age. Process model analysis demonstrated the effect of age on WM (P=0.001) and indicated an age-specific involvement of sleep quality (P=0.01). Whereas sleep duration was not associated with WM, at 4years of age, sleep disturbance with physical symptoms (e.g., breathing, motor) was associated with poor WM performance. Among 3-year-old girls, fear-related sleep disruption was associated with better WM performance. Together, the results suggest that the association between sleep and WM is dependent on: (a) specific aspects of sleep, (b) age, and (c) gender. More research is essential for unraveling the underlying neuro-maturational processes and mechanisms.

Relationships between gross motor skills, cardiovascular fitness, and visuospatial working memory-related brain activation in 8- to 10-year-old children

Relationships between gross motor skills and cardiovascular fitness with visuospatial working memory (VSWM) in children are hypothesized to be mediated by underlying functional brain mechanisms. Because there is little experimental evidence to support this mechanism, the present study was designed to investigate the relationships of gross motor skills and cardiovascular fitness with VSWM-related brain activation in 8- to 10-year-old children. Functional magnetic resonance imaging data obtained during a VSWM-task were analyzed for 80 children from grades 3 (47.5%) and 4 of 21 primary schools in the Netherlands (51.3% girls). Gross motor skills (Korper Koordinationstest für Kinder and Bruininks-Oseretsky Test of Motor Proficiency - 2nd Edition) and cardiovascular fitness (20-meter Shuttle Run Test) were assessed. VSWM-related brain activation was found in a network involving the angular gyrus, the superior parietal cortex, and the thalamus; deactivation was found in the inferior and middle temporal gyri. Although behavioral results showed significant relations of gross motor skills and cardiovascular fitness with VSWM performance, gross motor skills and cardiovascular fitness were not related to VSWM-related brain activation. Therefore, we could not confirm the hypothesis that brain activation underlies the relationship of gross motor skills and cardiovascular fitness with VSWM performance. Our results suggest that either the effects of physical activity on cognition do not necessarily go via changes in gross motor skills and/or cardiovascular fitness, or that brain activation patterns as measured with the blood-oxygen-level dependent (BOLD) signal may not be the mechanism underlying the relationships of gross motor skills and cardiovascular fitness with VSWM.

Autonomic Activity during a Daytime Nap Facilitates Working Memory Improvement

Recent investigations have implicated the parasympathetic branch of the autonomic nervous system in higher-order executive functions. These actions are purported to occur through autonomic nervous system's modulation of the pFC, with parasympathetic activity during wake associated with working memory (WM) ability. Compared with wake, sleep is a period with substantially greater parasympathetic tone. Recent work has reported that sleep may also contribute to improvement in WM. Here, we examined the role of cardiac parasympathetic activity during sleep on WM improvement in healthy young adults. Participants were tested in an operation span task in the morning and evening, and during the intertest period, participants experienced either a nap or wake. We measured high-frequency heart rate variability as an index of cardiac, parasympathetic activity during both wake and sleep. Participants showed the expected boost in parasympathetic activity during nap, compared with wake. Furthermore, parasympathetic activity during sleep, but not wake, was significantly correlated with WM improvement. Together, these results indicate that the natural boost in parasympathetic activity during sleep may benefit gains in prefrontal executive function in young adults. We present a conceptual model illustrating the interaction between sleep, autonomic activity, and prefrontal brain function and highlight open research questions that will facilitate understanding of the factors that contribute to executive abilities in young adults as well as in cognitive aging.

Autonomic/central coupling benefits working memory in healthy young adults

Working memory (WM) is an executive function that can improve with training. However, the precise mechanism for this improvement is not known. Studies have shown greater WM gains after a period of sleep than a similar period of wake, and correlations between WM improvement and slow wave activity (SWA; 0.5-1 Hz) during slow wave sleep (SWS). A different body of literature has suggested an important role for autonomic activity during wake for WM. A recent study from our group reported that the temporal coupling of Autonomic/CentralEvents (ACEs) during sleep was associated with memory consolidation. We found that heart rate bursts (HR bursts) during non-rapid eye movement (NREM) sleep are accompanied by increases in SWA and sigma (12-15 Hz) power, as well as increases in the high-frequency (HF) component of the RR interval, reflecting vagal rebound. In addition, ACEs predict long-term, episodic memory improvement. Building on these previous results, we examined whether ACEs also contribute to gains in WM. We tested 104 young adults in an operation span task (OSPAN) in the morning and evening, with either a nap (n = 53; with electroencephalography (EEG) and electrocardiography (ECG)) or wake (n = 51) between testing sessions. We identified HR bursts in the ECG and replicated the increases in SWA and sigma prior to peak of the HR burst, as well as vagal rebound after the peak. Furthermore, we showed sleep-dependent WM improvement, which was predicted by ACE activity. Using regression analyses, we discovered that significantly more variance in WM improvement could be explained with ACE variables than with overall sleep activity not time-locked with ECG. These results provide the first evidence that coordinated autonomic and central events play a significant role in sleep-related WM improvement and implicate the potential of autonomic interventions during sleep for cognitive enhancement.

What does a good night's sleep mean? Nonlinear relations between sleep and children's cognitive functioning and mental health

STUDY OBJECTIVES

We attempted to identify the duration and quality of sleep associated with the optimal child outcomes in key developmental domains including cognitive functioning, academic performance, and mental health. In doing so, we examined nonlinear associations between the sleep and developmental variables. Based on racial/ethnic disparities in children's sleep, we assessed this variable as a moderator of examined relations.

METHODS

Two hundred eighty-two children participated (Mage = 9.4 years, SD = .72; 52% boys; 65% white/European American, 35% black/African American). Sleep was examined with actigraphy for seven consecutive nights and with self-reports. Actigraphy-based sleep duration (minutes) and quality (efficiency), as well as self-reported sleep quality were derived. Children reported on their mental health and were administered cognitive performance tests. Mothers and teachers reported on children's mental health; teachers also reported on academic functioning. Schools provided academic achievement data.

RESULTS

Sleep duration had an accelerating nonlinear negative association with externalizing behaviors. Nonlinear associations were also detected between both actigraphy-derived and subjective reports of sleep quality and multiple developmental domains including academic functioning and mental health and the best functioning corresponded with the highest levels of sleep quality. Emphasizing the importance of individual differences, several examined associations were moderated by race/ethnicity.

CONCLUSIONS

Sleep duration and quality emerged as nonlinear predictors of multiple domains of child development. Findings illustrate that the benefits of longer and better-quality sleep did not taper off and that assessments of nonlinear relations may enhance understanding of the nature of associations between sleep and child functioning.

Experiments in the Wild: Introducing the Within-Person Encouragement Design

The within-person encouragement design introduced here combines methodological approaches from three research traditions: (a) the analysis of within-person couplings using multilevel models, (b) the experimental manipulation of a treatment variable at the within-person level, and (c) the use of random encouragements as instrumental variables to induce exogenous experimental variation when strict treatment adherence is unrealistic. The proposed combination of these approaches opens up new possibilities to study treatment effects of a broad range of behavioral variables in realistic everyday contexts. We introduce this new research design together with a corresponding data analysis framework: instrumental variable estimation with two-level structural equation models. Using simulations, we show that the approach is applicable with feasible design dimensions regarding numbers of measurement occasions and participants and realistic assumptions about adherence to the encouragement conditions. Possible applications and extensions, as well as potential problems and limitations are discussed.

Annual Research Review: Ecological momentary assessment studies in child psychology and psychiatry

BACKGROUND

Enhancements in mobile phone technology allow the study of children and adolescents' everyday lives like never before. Ecological momentary assessment (EMA) uses these advancements to allow in-depth measurements of links between context, behavior, and physiology in youths' everyday lives.

FINDINGS

A large and diverse literature now exists on using EMA to study mental and behavioral health among youth. Modern EMA methods are built on a rich tradition of idiographic inquiry focused on the intensive study of individuals. Studies of child and adolescent mental and behavioral health have used EMA to characterize lived experience, document naturalistic within-person processes and individual differences in these processes, measure familiar constructs in novel ways, and examine temporal order and dynamics in youths' everyday lives.

CONCLUSIONS

Ecological momentary assessment is feasible and reliable for studying the daily lives of youth. EMA can inform the development and augmentation of traditional and momentary intervention. Continued research and technological development in mobile intervention design and implementation, EMA-sensor integration, and complex real-time data analysis are needed to realize the potential of just-in-time adaptive intervention, which may allow researchers to reach high-risk youth with intervention content when and where it is needed most.

High occurrence of sleep problems in survivors of a childhood brain tumor with neurocognitive complaints: The association with psychosocial and behavioral executive functioning

BACKGROUND

Survivors of childhood brain tumors are prone to sleep and neurocognitive problems. Effective interventions to improve neurocognitive functioning are largely lacking. In general, sleep problems are negatively related to neurocognitive functioning, but this relationship is unclear in survivors of childhood brain tumors. Therefore, the occurrence of sleep problems, potential risk factors, and the relation between sleep and executive functioning were evaluated.

PROCEDURE

Baseline data of a randomized controlled trial on the effectiveness of neurofeedback were used. Childhood brain tumor survivors 8-18 years of age with parent-reported neurocognitive complaints ≥2 years after treatment were eligible. Parents completed the Sleep Disturbance Scale for Children. Executive functioning was assessed by parents and teachers (Behavior Rating Inventory of Executive Functioning). Multiple linear regression analyses were used to examine sociodemographic and medical characteristics and emotional difficulties and hyperactivity/inattention (Strength and Difficulties Questionnaire) as potential risk factors for sleep problems, and to assess the association between sleep and executive functioning.

RESULTS

Forty-eight percent of survivors (n = 82, 7.0 ± 3.6 years post diagnosis, age 13.8 ± 3.2 years) had sleep problems and scored significantly worse than the norm on the subscales Initiating and Maintaining Sleep, Excessive Somnolence, and the total scale (effect sizes 0.58-0.92). Emotional problems and/or hyperactivity/inattention were independent potential risk factors. Sleep problems were associated with worse parent-reported executive functioning.

CONCLUSIONS

Sleep problems occur among half of childhood brain tumor survivors with neurocognitive problems, and are associated with worse executive functioning. Future studies should focus on the development of sleep interventions for this population, to improve sleep as well as executive functioning.

A Daily Diary Analysis of Preschool Depressive Behaviors: Prospective Associations and Moderators Across 14 Days

Depressive disorders can be observed in early childhood and are associated with significant concurrent and prospective impairment; however, little is known about day-to-day variations in common depressive behaviors in children. This study examined the day-to-day variability of two common depressive behaviors in preschool-aged children, sadness and irritability, and factors associated with the daily occurrence of these behaviors. Participants included 291 parents of preschool-aged children, and parents completed a 14-day daily diary. Results indicated that sleep quality did not prospectively predict next-day sadness or irritability the following day. We observed between-person stability, but within-person variability, in children's sadness and irritability across 14 days. We observed greater between-person stability and greater within-person variability in sadness and irritability for males and for children with fewer baseline psychiatric symptoms and lower baseline impairment. Findings provide a developmental perspective on normative patterns of sadness and irritability in young children and can inform prevention and individualized intervention efforts to reduce negative sequelae in at-risk preschoolers.

A preliminary investigation of sleep quality and patient-reported outcomes in pediatric solid organ transplant candidates

The current cross-sectional, single-center study aimed to examine sleep quality in a sample of adolescents awaiting solid organ transplantation and to explore associations between sleep quality and both health-related quality of life and barriers to adherence. Thirty adolescents between the ages of 12 and 18 years (M age = 15.26, SD = 1.89) who were awaiting transplantation participated in this study. Participants completed measures of sleep quality, health-related quality of life, and barriers to adherence. T test and correlational analyses were performed to examine study aims. Adolescents awaiting transplantation had significantly lower levels of overall sleep quality compared to published norms of healthy peers. Domains of sleep quality were positively related to emotional and psychosocial health-related quality of life. Sleep quality domains were also negatively related to adherence barriers. This study provides preliminary evidence demonstrating that sleep quality among transplant candidates is compromised, and that poor sleep quality is related to adolescents' functioning across a number of domains during the pretransplant period. Results highlight the clinical importance of assessing and targeting sleep functioning in adolescents awaiting transplantation in order to reduce the negative influence of suboptimal sleep on functioning during this vulnerable period.

Estimating Reliability of Within-Person Couplings in a Multilevel Framework

Within-person couplings play a prominent role in psychological research and previous studies have shown that interindividual differences in within-person couplings predict future behavior. For example, stress reactivity-operationalized as the within-person coupling of stress and positive or negative affect-is an important predictor of various (mental) health outcomes and has often been assumed to be a more or less stable personality trait. However, issues of reliability of these couplings have been largely neglected so far. In this work, we present an estimate for the reliability of within-person couplings that can be easily obtained using the user-modifiable R code accompanying this work. Results of a simulation study show that this index performs well even in the context of unbalanced data due to missing values. We demonstrate the application of this index in a measurement burst study targeting the reliability and test-retest correlation of stress reactivity estimates operationalized as within-person couplings in a daily diary design. Reliability and test-retest correlations of stress reactivity estimates were rather low, challenging the implicit assumption of stress reactivity as a stable person-level variable. We highlight key factors that researchers planning studies targeting interindividual differences in within-person couplings should consider to maximize reliability.

Adiposity in Adolescents: The Interplay of Sleep Duration and Sleep Variability

OBJECTIVE

To assess whether adiposity measures differed according to joint categories of sleep duration and sleep variability in a sample of Mexican adolescents.

STUDY DESIGN

A sample of 528 Mexico City adolescents aged 9-17 years wore wrist actigraphs for 6-7 days. Average sleep duration was categorized as age-specific sufficient or insufficient. Sleep variability, the standard deviation of sleep duration, was split at the median into stable versus variable. Adiposity measures-body mass index (BMI)-for-age Z score (BMIz), triceps skinfolds, waist circumference, and percent body fat-were collected by trained assistants. We regressed adiposity measures on combined sleep duration and variability categories. Log binomial models were used to estimate prevalence ratios and 95% CI for obesity (>2 BMIz) by joint categories of sleep duration and variability, adjusting for sex, age, and maternal education.

RESULTS

Approximately 40% of the adolescents had insufficient sleep and 13% were obese. Relative to sufficient-stable sleepers, adolescents with insufficient-stable sleep had higher adiposity across all 4 measures (eg, adjusted difference in BMIz was 0.68; 95% CI, 0.35-1.00) and higher obesity prevalence (prevalence ratio, 2.54; 95% CI, 1.36-4.75). Insufficient-variable sleepers had slightly higher BMIz than sufficient-stable sleepers (adjusted difference, 0.30; 95% CI, 0.00-0.59).

CONCLUSIONS

Adolescents with consistently insufficient sleep could be at greater risk for obesity. The finding that insufficient-variable sleepers had only slightly higher adiposity suggests that opportunities for "catch-up" sleep may be protective.

Last night's sleep in relation to academic achievement and neurocognitive testing performance in adolescents with and without ADHD

OBJECTIVES/BACKGROUND

Objectives were to (1) examine previous night's sleep in relation to next day performance on standardized academic achievement and neurocognitive assessments in adolescents, and (2) explore whether previous night's sleep is differentially associated with testing performance for adolescents with and without attention-deficit/hyperactivity disorder (ADHD).

PARTICIPANTS/METHODS

Participants were 300 adolescents (ages 12-14 years; 55% male). Approximately half (53.6%) were diagnosed with ADHD. Adolescents provided ratings of their previous night's sleep quality, sleep duration, and number of night wakings and were administered standardized tests of processing speed and working memory, as well as word reading, numerical operations, and math fluency academic achievement.

RESULTS

In analyses controlling for sex, race, medication use, time of testing, and ADHD group status, more night wakings the previous night were associated with significantly lower numerical operations and math fluency achievement scores and marginally lower working memory scores. Previous night's sleep was not associated with processing speed or reading achievement. ADHD status did not moderate sleep in relation to academic/neurocognitive performance. Participants reporting ≥2 night wakings the previous night had slightly over half a standard deviation lower scores on average compared to participants reporting 0 night wakings.

CONCLUSIONS

This preliminary study suggests that previous night's wakings are associated with poorer mathematics performance the next day, regardless of ADHD status. This may be due to the detrimental effect of interrupted and fragmented sleep on attention and executive control. These findings have implications for clinicians and educators when considering contextual factors that may impact academic and neurocognitive testing performance.

Self-Reported Cognitive Failures in Everyday Life: A Closer Look at Their Relation to Personality and Cognitive Performance

A recent review concluded that the Cognitive Failures Questionnaire is the most widely used instrument to assess cognitive failures. Our aims were to place cognitive failures self-reported with the Cognitive Failures Questionnaire into their nomological network by conceptually replicating known relations to the Big Five and by extending this knowledge through testing their relations with latent cognitive abilities (Study 1, N = 158, age 20-86 years) and theoretically relevant Big Five subfacets (Study 2, N = 176, age 19-39 years). Cognitive failures were unrelated to objective cognitive performance (processing speed, memory, and inhibition), but reliably related to the personality domains conscientiousness, neuroticism, and almost all their subfacets. Thus, self-reported cognitive failures do not qualify as a proxy for objective cognitive performance tasks. They are rather useful as illustration of behavioral manifestations related to personality domains.

Configural face perception in childhood and adolescence: An individual differences approach

Cognitive experimental and neuroscientific research in adults indicates that an important property of face perception is its specificity and reliance on configural processing. In addition, individual differences in face perception between adults cannot be entirely explained through general cognitive functioning and object cognition. Although recent years have witnessed growing interest in the development of face perception through childhood and adolescence, as yet, little is known about individual differences in configural face perception in this period of life, and whether these differences are face-specific. Here, we addressed these questions in a large sample (N = 338) drawn continuously from age six to 21. We applied a face composite task and a spatial manipulation task including stimulus inversion. Immediate and delayed face memory were assessed as covariates of configural face perception. Content specificity in configural face perception was tested by analogous tasks with houses as stimuli. In addition, we measured working memory and fluid intelligence. Our results show that there are large individual differences in configural face perception across the entire age range from six to 21 years. Supporting theories of early maturation, configural face perception was almost adult-like already at age six. Individual differences in configural face perception were related with immediate and delayed face memory and fluid intelligence across the whole age range. In sum, we provide novel evidence on large individual differences in configural face and object perception already in middle childhood, complementing findings from aging studies and providing new perspectives for further research.

Variability in the Precision of Children's Spatial Working Memory

Cognitive modeling studies in adults have established that visual working memory (WM) capacity depends on the representational precision, as well as its variability from moment to moment. By contrast, visuospatial WM performance in children has been typically indexed by response accuracy—a binary measure that provides less information about precision with which items are stored. Here, we aimed at identifying whether and how children’s WM performance depends on the spatial precision and its variability over time in real-world contexts. Using smartphones, 110 Grade 3 and Grade 4 students performed a spatial WM updating task three times a day in school and at home for four weeks. Measures of spatial precision (i.e., Euclidean distance between presented and reported location) were used for hierarchical modeling to estimate variability of spatial precision across different time scales. Results demonstrated considerable within-person variability in spatial precision across items within trials, from trial to trial and from occasion to occasion within days and from day to day. In particular, item-to-item variability was systematically increased with memory load and lowered with higher grade. Further, children with higher precision variability across items scored lower in measures of fluid intelligence. These findings emphasize the important role of transient changes in spatial precision for the development of WM.

Genotype Influences Day-to-Day Variability in Sleep in Drosophila melanogaster

Patterns of sleep often vary among individuals. But sleep and activity may also vary within an individual, fluctuating in pattern across time. One possibility is that these daily fluctuations in sleep are caused by the underlying genotype of the individual. However, differences attributable to genetic causes are difficult to distinguish from environmental factors in outbred populations such as humans. We therefore employed Drosophila as a model of intra-individual variability in sleep using previously collected sleep and activity data from the Drosophila Genetic Reference Panel, a collection of wild-derived inbred lines. Individual flies had significant daily fluctuations in their sleep patterns, and these fluctuations were heritable. Using the standard deviation of sleep parameters as a metric, we conducted a genome-wide association study. We found 663 polymorphisms in 104 genes associated with daily fluctuations in sleep. We confirmed the effects of 12 candidate genes on the standard deviation of sleep parameters. Our results suggest that daily fluctuations in sleep patterns are due in part to gene activity.