Early Life Socioeconomic Differences in Associations between Childhood Sleep and Academic Performance.

Poor sleep can negatively impact children's academic performance. However, it is unknown whether early-life socioeconomic status (SES) moderates later sleep and academics. We tested associations between actigraphy-based sleep duration and midpoint time, and parent-reported sleep problems with objective and subjective measures of academic performance. We also examined whether relations varied by early and concurrent SES. Children (n=707; 52% female; M age=8.44 years; 28.7% Hispanic/Latinx; 29.7% at/below poverty line) were assessed at 12 months for SES and eight years for SES, sleep, and academics. There were no main effects of sleep on academics. More sleep problems predicted lower Applied Problems performance for low SES children (b=-.73, p<.05) and better performance for high SES children (b=.69, p<.05). For high SES children, greater sleep problems (b=-.11, p<.05) and longer sleep duration (b=-.11, p<.05) predicted lower academic achievement. However, most associations were consistent across SES, illustrating the complex interplay between sleep, academic outcomes, and SES.

Harsh Parenting Predicts Novel HPA Receptor Gene Methylation and NR3C1 Methylation Predicts Cortisol Daily Slope in Middle Childhood.

Adverse experiences in childhood are associated with altered hypothalamic-pituitary-adrenal (HPA) axis function and negative health outcomes throughout life. It is now commonly accepted that abuse and neglect can alter epigenetic regulation of HPA genes. Accumulated evidence suggests harsh parenting practices such as spanking are also strong predictors of negative health outcomes. We predicted harsh parenting at 2.5 years old would predict HPA gene DNA methylation similarly to abuse and neglect, and cortisol output at 8.5 years old. Saliva samples were collected three times a day across 3 days to estimate cortisol diurnal slopes. Methylation was quantified using the Illumina Infinium MethylationEPIC array BeadChip (850 K) with DNA collected from buccal cells. We used principal components analysis to compute a summary statistic for CpG sites across candidate genes. The first and second components were used as outcome variables in mixed linear regression analyses with harsh parenting as a predictor variable. We found harsh parenting significantly predicted methylation of several HPA axis genes, including novel gene associations with AVPRB1, CRHR1, CRHR2, and MC2R (FDR corrected p < 0.05). Further, we found NR3C1 methylation predicted a steeper diurnal cortisol slope. Our results extend the current literature by demonstrating harsh parenting may influence DNA methylation similarly to more extreme early life experiences such as abuse and neglect. Further, we show NR3C1 methylation is associated with diurnal HPA function. Elucidating the molecular consequences of harsh parenting on health can inform best parenting practices and provide potential treatment targets for common complex disorders.

Pediatric recurring pain in the community: the role of children's sleep and internalizing symptoms.

Associations between poor sleep and pain may be amplified for children who also have depressive or anxious symptoms. This study examined associations between child sleep at eight years and recurrent pain at nine years along with the moderating role of internalizing symptoms. Families were from a community-based, ongoing longitudinal study (N = 632 children). At eight and nine years, twins (49.2% female, 56.7% non-Latinx European American, 28.8% Latinx) and caregivers participated in assessments focused on child sleep and pain, respectively. Approximately 53% of children had pain in at least one location at least monthly. Internalizing symptoms at age eight were positively associated with number of pain sites at age nine. Lower sleep efficiencies were associated with more pain sites for children with higher levels of internalizing symptoms. Later midpoint times were associated with more pain sites for children with lower levels of internalizing symptoms. Interventions focused on improving children's pain outcomes may consider targeting sleep behaviors and mental health.

Daily rumination about stress, sleep, and diurnal cortisol activity.

Rumination is an involuntary cognitive process theorized to prolong arousal and inhibit proper emotion regulation. Most available research has examined individual differences in cognitive dispositions to ruminate about stress as a risk marker for psychopathology and other health problems. This intensive longitudinal study extended previous research by examining day-to-day associations of rumination about stress with objectively-measured actigraph-based sleep and diurnal salivary cortisol activity. Sixty-one healthy participants (Mage = 20.91) completed up to five ecological momentary assessments (EMA) each day and wore actigraph wristwatches for eight days (N = 488). On three of these days, participants provided five saliva samples assayed for cortisol (N = 910). On average, greater daily stress levels were associated with shorter sleep duration and higher waking cortisol levels. In day-to-day analyses, greater daily stress levels, when combined with ruminating about daily stress more than usual, was associated with higher waking cortisol levels the following morning. Ruminating more than usual about daily stress, in the context of low-stress days, was also associated with flatter diurnal cortisol slopes the next day. These findings highlight the potential influences of daily stress, and rumination about stress, on sleep and diurnal cortisol activity - two important markers of health and well-being.

Early Life Socioeconomic Disparities in Children's Sleep: The Mediating Role of the Current Home Environment.

Despite identified concurrent socioeconomic disparities in children's sleep, little research has examined pathways explaining such associations. This study examined the quality of the home environment as a direct predictor of sleep and potential mediator of associations between early life socioeconomic status and objective and subjective indicators of sleep in middle childhood. A socioeconomically and ethnically diverse sample of 381 twin children (50% female; 46.6% lower middle class or living at or below the poverty line; 26% Hispanic/Latino) were assessed at 12 months for SES and eight years using gold-standard home environment interviews and actigraphy-measured sleep. Multilevel mediation path models indicated that lower early SES and lower quality concurrent home environments were associated with shorter sleep durations, longer sleep latencies, and greater sleep timing variability. The home environment significantly mediated associations with sleep duration and sleep timing variability. The findings illustrate an important target in the prevention of poor childhood and adolescent sleep.

Cultural neurobiology and the family: Evidence from the daily lives of Latino adolescents.

Culturally linked family influences during adolescence are important predictors of health and well-being for Latino youth, yet few studies have examined whether these familial influences are associated with indicators of typical physiological stress processes. Following a cultural neurobiology framework, we examined the role of family in the everyday lives of Latino adolescents (N = 209; Mage = 18.10; 85.1% Mexican descent; 64.4% female) by investigating familism values and perceptions of parent support as well as daily family assistance behaviors in relation to hypothalamic-pituitary-adrenal axis diurnal patterns, indexed by salivary cortisol five times a day for 3 weekdays. Three-level growth curve analyses revealed that perceptions of parental support were associated with greater cortisol awakening responses, whereas familism values were not associated with diurnal cortisol patterns. In day-to-day analyses, assisting family during the day (compared to not assisting family) was associated with lower waking cortisol levels and flatter diurnal slopes the next day. Our findings highlight the dynamic associations and multiple time courses between cultural values and behaviors, daily experiences, and physiological stress processes for Latino adolescents. Further, we identified important cultural risk and promotive factors associated with physiological regulation in daily life and potential pathways toward health outcomes in adulthood.

Multi-method assessments of sleep over the transition to college and the associations with depression and anxiety symptoms.

A growing body of research has demonstrated links between sleep problems and symptoms of depression and anxiety in community and clinical samples of adolescents and young adults. Scant longitudinal research, however, has examined reciprocal associations over socio-contextual shifts such as the transition to college. Using multiple methods of assessment (e.g., actigraphy, subjective report), the current study assessed whether sleep quantity, quality or variability changed over the transition to college and investigated the potential cross-lagged relationships between adolescents' sleep and symptoms of anxiety and depression. The participants (N = 82; 24% male) were studied at three time points over approximately 1 year: spring of their senior year of high school (T1), fall of their first year of college (T2), and spring of their first year of college (T3). Sleep minutes, sleep efficiency, wake time variability and anxiety increased over the transition to college. Subjective reports of sleep problems decreased. Cross-lagged panel models indicated significant relationships between subjective sleep quality and anxiety symptoms over time where subjective sleep problems at T1 were associated with anxiety at T2, and anxiety at T2 was associated with subjective sleep problems at T3. In contrast, greater depressive symptoms at T1 preceded increases in subjective sleep problems, sleep latency and sleep start time variability at T2. Importantly, there were concurrent associations between symptoms of anxiety or depression at T2 and sleep efficiency, sleep start time variability, and subjective sleep problems. These findings suggest that, overall, sleep quantity and quality improved over the transition to college, although the overall amounts of sleep were still below developmental recommendations. However, for some youth, the first semester of college may be a sensitive period for both sleep problems and symptoms of anxiety. In contrast, depressive symptoms were stable across time but were associated with worsening sleep problems in the first semester of college. Implications for future prevention and intervention programs should include strategies to help youth cope effectively with adjustment like increased sleep variability and symptoms of anxiety associated with the transition to college.

Coping in the Digital Age: Do Coping Strategies Mediate the Link Between Online and In-Person Victimization and Depressive Symptoms?

With increased use of social networking sites in recent years, there has also been an increased opportunity for users to fall prey to bullying victimization. However, little is known about the differences between online and in-person victimization in association with depression or how different coping strategies may mediate this relationship among college students. The goal of the current study was to examine whether there were similarities or differences in the extent to which self-reported online and in-person victimization were associated with depressive symptoms in a sample of 210 undergraduate students (72.9% Women; 85.4% Cauasian), as well as whether different problem- and emotion-focused coping may differentially mediate the links between young adult victimization and depressive symptoms. Participants reported depressive symptoms, problem- and emotion-focused coping, and in-person and online victimization. In-person and online victimization independently predicted emotion-focused coping and depressive symptoms in young adults, and both problem- and emotion-focused coping predicted depressive symptoms. Further, emotion-focused coping partially mediated the effect of in-person victimization and depressive symptoms, suggesting that training more effective coping strategies may be an important intervention target to reduce depressive symptoms for those experiencing bullying victimization. Future research should continue to explore how different coping strategies act as a mechanism between victimization and depressive symptoms.

Concordance in parent-child and sibling actigraphy-measured sleep: Evidence among early adolescent twins and primary caregivers.

STUDY OBJECTIVES: Growing evidence suggests concordance between parent and youth sleep. However, no known study has simultaneously examined concordance among siblings' sleep patterns. This study investigated daily and average concordance in (1) parent-youth and (2) sibling actigraphy-measured sleep, as well as the degree to which sibling concordance varied by sleeping arrangements. METHODS: 516 twin siblings (Mage = 10.74, 51% female; 30% monozygotic (MZ) twin pairs, 37% same-sex dizygotic pairs (DZ-ss), 33% opposite-sex DZ pairs (DZ-os)) and their primary caregivers (Mage = 40.59, 95% female) wore wrist-based accelerometers for 7 consecutive nights to measure sleep duration, efficiency, midpoint time, and latency. Primary caregivers also reported on demographics, youth pubertal status, and room-sharing. Two-level multilevel models were estimated to examine daily and average concordance in parent-youth and sibling sleep. RESULTS: Daily concordance was observed between parent and youth sleep duration and midpoint; average concordance was found for sleep duration, midpoint, and latency. Within sibling dyads, daily and average concordance was evident across all sleep parameters (duration, efficiency, midpoint, latency), with generally stronger concordance patterns for MZ than DZ twin pairs, and for twins who shared a room with their co-twin. CONCLUSIONS: This is the first known study to document concordance among parent-youth and siblings' actigraphy-measured sleep within the same study (i.e., triad). Our findings can help inform the development of family-level interventions targeting daily and overall sleep hygiene.

Children's objective sleep assessed with wrist-based accelerometers: strong heritability of objective quantity and quality unique from parent-reported sleep.

Children's poor sleep is a risk factor for lower cognitive functioning and internalizing and externalizing problems. It is unclear whether genetic and environmental influences vary based on sleep assessment and no studies to date have examined genetic and environmental contributions to links between multiple objective and subjective sleep indicators. Further, nearly all heritability studies rely on subjective parent- or self-report measures of sleep duration and problems. Given these gaps in the literature, we (1) modeled genetic and environmental influences on multiple objective and subjective sleep indicators and (2) estimated genetic and environmental covariances between objective and subjective sleep indicators in middle childhood. Participants were 608 twin children (MZ = 178, same-sex DZ = 234, opposite-sex DZ = 190) assessed at 8 years of age (SD = 0.63 years). Objective nighttime sleep duration, efficiency, sleep onset latency (SOL), midpoint time, and midpoint variability were collected from actigraph watches worn for 7 nights (Mnights = 6.83, SD = 0.62). Children's nighttime sleep duration and daytime sleepiness were assessed via parent report. Findings suggested high additive genetic influence on objective sleep quantity and quality, whereas objective SOL, sleep midpoint time, midpoint variability, parent-reported sleep duration, and daytime sleepiness were largely influenced by the shared environment. Common genetic factors explained associations between objective sleep quantity and quality, but genetics did not account for links with parent-reported sleep duration, midpoint time, or midpoint variability. Thus, objective and parent-reported assessments of children's sleep have unique genetic etiologies and should not be used interchangeably in the sleep literature.

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.

Early life socioeconomic status moderates associations between objective sleep and weight-related indicators in middle childhood.

OBJECTIVES: This study tested whether early socioeconomic status moderated links between objective and subjective sleep and weight indicators during middle childhood. DESIGN: The study design was cross-sectional but included data from earlier assessment points in the study. SETTING: Data were collected from families across the state of Arizona. PARTICIPANTS: Participants were 382 children recruited from birth records (49.5% female; Mage = 8.47 years; 56.5% European American; 25.1% Latino; 25% living at or below the poverty line). MEASUREMENTS: Assessments included socioeconomic status at 12 months of age, and sleep and weight indicators at 8 years. RESULTS: Longer sleep durations predicted lower body mass index and decreased odds of being overweight/obese across all children, regardless of socioeconomic background. For children from low socioeconomic backgrounds, longer sleep duration predicted lower percent body fat, greater efficiency predicted lower percent body fat and body mass index and smaller waist circumference, and more sleep problems predicted larger waist circumference. For children from low socioeconomic backgrounds, greater sleep duration and efficiency also predicted the lowest odds of being overweight/obese, and more sleep problems predicted the greatest odds of being overweight/obese. CONCLUSIONS: Early life may be a sensitive period that sets the stage for stronger links between sleep and weight indicators in middle childhood. Findings offer important information regarding the protective role of sleep in the promotion of health, as well as the negative consequences that may be stronger for children who experienced low early-life socioeconomic status.

Dopaminergic gene methylation is associated with cognitive performance in a childhood monozygotic twin study.

Individual differences in cognitive function are due to a combination of heritable and non-heritable factors. A large body of evidence from clinical, cognitive, and pharmacological neuroscience implicates dopaminergic gene variants as modulators of cognitive functions. Neuroepigenetic studies demonstrate environmental factors also influence complex phenotypes by affecting gene expression regulation. To evaluate the mechanism of environmental influence on cognitive abilities, we examined if epigenetic regulation of dopaminergic genes plays a role in cognition. Using a DNA methylation profiling microarray, we used a monozygotic (MZ) twin difference design to evaluate if co-twin differences in methylation of CpG sites near six dopaminergic genes predicted differences in response inhibition and memory performance. Studying MZ twins allows us to assess if environmentally driven differences in methylation affect differences in phenotype while controlling for the influence of genotype and shared family environment. Response inhibition was assessed with the flanker task and short-term and working memory were assessed with digit span recall. We found MZ co-twin differences in DRD4 gene methylation predicted differences in short-term memory. MZ differences in COMT, DBH, DAT1, DRD1, and DRD2 gene methylation predicted differences in response inhibition. Taken together, findings suggest methylation status of dopaminergic genes may influence cognitive functions in a dissociable manner. Our results highlight the importance of the epigenome and environment, over and above the influence of genotype, in supporting complex cognitive functions.

Children's sleep and daytime functioning: Increasing heritability and environmental associations with sibling conflict.

Children's sleep has both environmental and genetic influences, with stressful family environmental factors like household chaos and marital conflict associated with sleep duration and quality (El-Sheikh, Buckhalt, Mize, & Acebo, 2006; Fiese, Winter, Sliwinski, & Anbar, 2007). However, it is less clear whether sibling conflict is related to sleep duration and children's sleep problems (e.g., nighttime wakings, parasomnias). In addition, few studies have tested whether associations between sleep and stressful family environmental factors are accounted for by an underlying set of genes or shared and unique environmental factors. Participants were 582 twins with sleep assessed longitudinally at 12, 30 months, and 5 years of age. Sibling conflict was assessed at 5 years. Greater sibling conflict was associated with shorter sleep duration and greater number of total sleep problems, over and above the influence of general household stress and other covariates. The heritability of sleep duration increased with age. Shared environmental factors accounted for the covariance between sibling conflict and sleep duration and total sleep problems. Findings hold promise for interventions, including educating parents about fostering positive sibling relationships and healthy sleep habits.