Emergence of racial/ethnic and socioeconomic differences in objectively measured sleep-wake patterns in early infancy: results of the Rise & SHINE study

Perceived childhood neighborhood safety and sleep health during childhood and adulthood among a cohort of African American women

OBJECTIVE

To investigate associations between perceived childhood neighborhood safety and sleep over the life course.

METHODS

Among a cohort of 1693 Black/African American women aged 23-35 years at enrollment (2010-2012), participants recalled neighborhood safety (safe vs. unsafe) when they were 5, 10, and 15 years old. Participants' mothers/caregivers and participants reported sleep-related health behaviors at age 5. We used ordinal logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for sleep-related health behaviors (i.e., rarely/never or sometimes vs. mostly/always going to bed by 8:00 p.m., bed in a quiet room, bed in a dimly lit or unlit room), separately. Adulthood sleep duration and insomnia symptoms were reported at enrollment and over three follow-up periods. We applied generalized estimating equations to log binomial regression models to estimate relative risks (RR) for adulthood sleep characteristics.

RESULTS AND CONCLUSIONS

Four percent of participants reported an unsafe neighborhood at age 5 years, only, and 12% reported an unsafe neighborhood at all ages. Participants in perceived unsafe vs. safe neighborhoods at age 5 had higher odds of poor sleep-related health behaviors (e.g., rarely/never or sometimes going to bed in a quiet room: OR = 1.73 [1.27-2.35]). Participants in perceived unsafe vs. safe neighborhoods throughout childhood had higher risk of short sleep (RR = 1.10 [1.02-1.18]) and insomnia symptoms (RR = 1.07 [1.00-1.15]) during adulthood after adjustment for life course socioeconomic characteristics and adulthood health behaviors and characteristics. Perceived unsafe childhood neighborhood was associated with poorer sleep over the life course and may serve as an early intervention target.

The Negative Effects of Travel on Student Athletes Through Sleep and Circadian Disruption

Collegiate athletes must satisfy the academic obligations common to all undergraduates, but they have the additional structural and social stressors of extensive practice time, competition schedules, and frequent travel away from their home campus. Clearly such stressors can have negative impacts on both their academic and athletic performances as well as on their health. These concerns are made more acute by recent proposals and decisions to reorganize major collegiate athletic conferences. These rearrangements will require more multi-day travel that interferes with the academic work and personal schedules of athletes. Of particular concern is additional east-west travel that results in circadian rhythm disruptions commonly called jet lag that contribute to the loss of amount as well as quality of sleep. Circadian misalignment and sleep deprivation and/or sleep disturbances have profound effects on physical and mental health and performance. We, as concerned scientists and physicians with relevant expertise, developed this white paper to raise awareness of these challenges to the wellbeing of our student-athletes and their co-travelers. We also offer practical steps to mitigate the negative consequences of collegiate travel schedules. We discuss the importance of bedtime protocols, the availability of early afternoon naps, and adherence to scheduled lighting exposure protocols before, during, and after travel, with support from wearables and apps. We call upon departments of athletics to engage with sleep and circadian experts to advise and help design tailored implementation of these mitigating practices that could contribute to the current and long-term health and wellbeing of their students and their staff members.

A longitudinal study of infant 24-hour sleep: comparisons of sleep diary and accelerometer with different algorithms

STUDY OBJECTIVES

To longitudinally compare sleep/wake identification and sleep parameter estimation from sleep diaries to accelerometers using different algorithms and epoch lengths in infants.

METHODS

Mothers and other caregivers from the Nurture study (southeastern United States, 2013-2018) reported infants' 24-hour sleep in sleep diaries for 4 continuous days, while infants concurrently wore accelerometers on the left ankle at 3, 6, 9, and 12 months of age. We applied the Sadeh, Sadeh Infant, Cole, and Count-scaled algorithm to accelerometer data at 15 and 60 seconds epochs. For sleep/wake identification, we assessed agreement by calculating epoch-by-epoch percent agreement and kappas. We derived sleep parameters from sleep diaries and accelerometers separately and evaluated agreement using Bland-Altman plots. We estimated longitudinal trajectories of sleep parameters using marginal linear and Poisson regressions with generalized estimation equation estimation.

RESULTS

Among the 477 infants, 66.2% were black and 49.5% were female. Agreement for sleep/wake identification varied by epoch length and algorithm. Relative to sleep diaries, we observed similar nighttime sleep offset, onset, and total nighttime sleep duration from accelerometers regardless of algorithm and epoch length. However, accelerometers consistently estimated about 1 less nap per day using the 15 seconds epoch, 70 and 50 minutes' shorter nap duration per day using the 15 and 60 seconds epoch, respectively; but accelerometers estimated over 3 times more wake after nighttime sleep onset (WASO) per night. Some consistent sleep parameter trajectories from 3 to 12 months from accelerometers and sleep diaries included fewer naps and WASOs, shorter total daytime sleep, longer total nighttime sleep, and higher nighttime sleep efficiency.

CONCLUSIONS

Although there is no perfect measure of sleep in infancy, our findings suggest that a combination of accelerometer and diary may be needed to adequately measure infant sleep.

Disparities in Sleep-Disordered Breathing: Upstream Risk Factors, Mechanisms, and Implications

Sleep-disordered breathing (SDB) refers to a spectrum of disorders ranging from habitual snoring without frank episodes of obstructed breathing or desaturation during sleep to obstructive sleep apnea, where apneas and hypopneas repetitively occur with resultant intermittent hypoxia, arousal, and sleep disruption. Disparities in SDB reflect its overall high prevalence in children and adults from racially and ethnically minoritized or low socioeconomic status backgrounds coupled with high rates of underdiagnosis and suboptimal treatment.

Consensus statement on Singapore integrated 24-hour activity guide for early childhood

Introduction

Early childhood is a critical period for growth and development. Adopting healthy lifestyle behaviours during this period forms the foundation for future well-being and offers the best protection against non-communicable diseases. Singapore studies have shown that many young children are not achieving the recommendations on physical activity, sedentary behaviour and sleep. A workgroup was set up to develop recommendations for caregivers of infants, toddlers and preschoolers (aged <7 years) on how to integrate beneficial activities within a daily 24-hour period for optimal development and metabolic health.

Method

The Grading of Recommendations Assessment, Development and Evaluation (GRADE)- ADOLOPMENT approach was employed for adoption, adaption or de novo development of recommendations. International and national guidelines were used as references, and an update of the literature reviews up to September 2021 was conducted through an electronic search of PubMed, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) databases.

Results

Four consensus statements were developed for each age group: infants, toddlers and preschoolers. The statements focus on achieving good metabolic health through regular physical activity, limiting sedentary behaviour, achieving adequate sleep and positive eating habits. The 13th consensus statement recognises that integration of these activities within a 24-hour period can help obtain the best results.

Conclusion

This set of recommendations guides and encourages caregivers of Singapore infants, toddlers and preschoolers to adopt beneficial lifestyle activities within each 24-hour period.

Health Disparities in Pediatric Sleep

This article reviews disparities in pediatric sleep health and sleep disorders from early childhood through adolescence (birth to age 18 years). Sleep health is a multidimensional construct including sleep duration, consolidation, and other domains, whereas sleep disorders reflect both behaviorally (eg, insomnia) and medically based (eg, sleep disordered breathing) sleep diagnoses. Using a socioecological framework, we review multilevel (ie, child, family, school, health-care system, neighborhood, and sociocultural) factors linked to sleep health disparities. Mechanistic research and studies using an intersectional lens to understand overlapping marginalized identities are needed to inform multilevel interventions to promote sleep health equity in pediatrics.

Development and Psychometric Properties of the Sleep Parenting Scale for Infants

Although infants' sleep behaviors are shaped by their interactions with parents at bedtime, few tools exist to capture parents' sleep parenting practices. This study developed a Sleep Parenting Scale for Infants (SPS-I) and aimed to (1) explore and validate its factorial structure, (2) examine its measurement invariance across mothers and fathers, and (3) investigate its reliability and concurrent and convergent validity. SPS-I was developed via a combination of items modified from existing scales and the development of novel items. Participants included 188 mothers and 152 mother-father dyads resulting in 340 mothers and 152 fathers; about half were non-Hispanic white. Mothers and fathers completed a 14-item SPS-I for their 12-month-old infant. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to explore and validate SPS-I's underlying structure. Multigroup CFA was used to examine measurement invariance across mothers and fathers. Reliability was examined using Cronbach's alpha. Concurrent validity was assessed using linear regressions examining associations between SPS-I factors and parent-reported infants nighttime sleep duration. Convergent validity was assessed using paired-sample t-tests to test whether the SPS-I subscale scores were similar between mothers and fathers in the same household. EFA and CFA confirmed a 3-factor, 12-item model: sleep routines, sleep autonomy, and screen media in the sleep environment. SPS-I was invariant across mothers and fathers and was reliable. Concurrent and convergent validity were established. SPS-I has good psychometric properties, supporting its use for characterizing sleep routines, sleep autonomy, and screen media in the sleep environment by mothers and fathers.Supplemental data for this article is available online at https://doi.org/10.1080/08964289.2021.2002799 .

ABM Clinical Protocol #37: Physiological Infant Care-Managing Nighttime Breastfeeding in Young Infants

A central goal of the Academy of Breastfeeding Medicine (ABM) is the development of clinical protocols for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient. The ABM empowers health professionals to provide safe, inclusive, patient-centered, and evidence-based care. Pregnant and lactating people identify with a broad spectrum of genders, pronouns, and terms for feeding and parenting. There are two reasons ABM's use of gender-inclusive language may be transitional or inconsistent across protocols. First, gender-inclusive language is nuanced and evolving across languages, cultures, and countries. Second, foundational research has not adequately described the experiences of gender-diverse individuals. Therefore, ABM advocates for, and will strive to use language that is as inclusive and accurate as possible within this framework. For more explanation, please read ABM Position Statements on Infant Feeding and Lactation-Related Language and Gender (https://doi.org/10.1089/bfm.2021.29188.abm) and Breastfeeding As a Basic Human Right (https://doi.org/10.1089/bfm.2022.29216.abm).

Longitudinal changes in term and preterm infant night wakings: The role of caregiver anxious-depression

Changes in infant night waking during the first year of life are associated with individual (e.g., prematurity) and family (e.g., caregiver psychopathology) factors. This study examined the association between infant night waking and caregiver anxious-depressive symptoms during the first year of life in preterm and term infants. We considered between-person differences and within-person changes in caregiver anxious-depressive symptoms in relation to changes in infant night waking from 2- to 9-months. Racially (30.0% Black, 60.4% White, 9.5% multiracial/other) and socioeconomically (40.0% below median household income) diverse caregivers (N = 445) of full term (n = 258) and preterm (n = 187) infants were recruited from hospitals and clinics in two midwestern states. Caregivers completed measures of anxious-depression and their infant's night waking at four sampling periods (2-, 4-, 6-, and 9-months). Infant night wakings declined from 2- to 9-months. Between-person differences were observed, such that caregivers with higher average anxious-depressive symptoms or infants born full term reported more night wakings. Within-person effects of caregiver anxious-depressive symptoms were not significant. Caregiver anxious-depression is closely associated with infant night wakings. By considering a caregiver's average severity of anxious-depression, healthcare providers can more effectively plan infant sleep interventions. If caregiver anxious-depressive symptoms are ameliorated, night wakings may also decrease.

Racial/ethnic disparities in infant sleep in the COVID-19 Mother Baby Outcomes (COMBO) study

OBJECTIVE

Investigate racial and ethnic differences in infant sleep and examine associations with insurance status and parent-infant bedtime behavioral factors (PIBBF).

METHODS

Participants are part of the COVID-19 Mother Baby Outcomes (COMBO) Initiative, Columbia University. Data on infant sleep (night, day and overall sleep duration, night awakenings, latency, infant's sleep as a problem) were collected at 4 months postpartum. Regressions estimated associations between race/ethnicity, insurance status, PIBBF and infants' sleep.

RESULTS

A total of 296 infants were eligible (34.4% non-Hispanic White [NHW], 10.1% Black/African American [B/AA], 55.4% Hispanic). B/AA and Hispanic mothers were more likely to have Medicaid, bed/room-share, and report later infant bedtime compared to NHW mothers. Infants of B/AA mothers had longer sleep latency compared to NHW. Infants of Hispanic mothers slept less at night (∼70 ± 12 minutes) and more during the day (∼41 ± 12 minutes) and Hispanic mothers were less likely to consider infants' sleep as a problem compared to NHW (odds ratio 0.4; 95% confidence interval: 0.2-0.7). After adjustment for insurance status and PIBBF, differences by race/ethnicity for night and day sleep duration and perception of infant's sleep as a problem persisted (∼32 ± 14 minutes, 35 ± 15 minutes, and odds ratio 0.4; 95% confidence interval: 0.2-0.8 respectively). Later bedtime was associated with less sleep at night (∼21 ± 4 minutes) and overall (∼17 ± 5 minutes), and longer latency. Infants who did not fall asleep independently had longer sleep latency, and co-sleeping infants had more night awakenings.

CONCLUSIONS

Results show racial/ethnic differences in sleep in 4-month-old infants across sleep domains. The findings of our study suggest that PIBBF have an essential role in healthy infant sleep, but they may not be equitably experienced across racial/ethnic groups.

Co-Rooming Accounts for Socioeconomic Disparities in Infant Sleep Quality among Families Living in Urban Environments

Poor infant sleep quality is associated with negative maternal and infant health outcomes. This study measures socioeconomic disparities in infant sleep quality, and assesses whether child sleep location and maternal stress mediate associations between socioeconomic status (SES) and infant sleep quality. The study includes 86 socioeconomically diverse, mother-infant dyads living in an urban area with infants aged 6–12 months. Mothers reported socioeconomic demographics, infant sleep quality (Brief Infant Sleep Questionnaire) and maternal subjective stress (Perceived Stress Scale). Maternal objective stress was measured via hair cortisol concentration (HCC). The associations among SES, infant sleep quality, infant co-rooming, and maternal stress were assessed. Infants from families with lower income-to-needs (ITN) ratios had poorer infant sleep quality. The association between familial ITN and infant sleep quality was mediated by whether the child co-rooms with parents. Maternal perceived stress was independently associated with infant sleep quality, but HCC was not associated with infant sleep quality.

Disparities in sleep duration among American children: effects of race and ethnicity, income, age, and sex

Children in the United States sleep less than the recommended amount and sleep deficiencies may be worse among disadvantaged children. Prior studies that compared sleep time in children of different race/ethnic groups mostly relied on questionnaires or were limited to small sample sizes. Our study takes advantage of the Adolescent Brain Cognitive Development study to compare total sleep time using a week of actigraphy data among American children (n = 4,207, 9 to 13 y old) of different racial/ethnic and income groups. We also assessed the effects of neighborhood deprivation, experience of discrimination, parent's age at child's birth, body mass index (BMI), and time the child fell asleep on sleep times. Daily total sleep time for the sample was 7.45 h and race/ethnicity, income, sex, age, BMI, were all significant predictors of total sleep time. Black children slept less than White children (∼34 min; Cohen's d = 0.95), children from lower income families slept less than those from higher incomes (∼16 min; Cohen's d = 0.44), boys slept less than girls (∼7 min; Cohen's d = 0.18), and older children slept less than younger ones (∼32 min; Cohen's d = 0.91); mostly due to later sleep times. Children with higher BMI also had shorter sleep times. Neither area deprivation index, experience of discrimination, or parent's age at child's birth significantly contributed to sleep time. Our findings indicate that children in the United States sleep significantly less than the recommended amount for healthy development and identifies significant racial and income disparities. Interventions to improve sleep hygiene in children will help improve health and ameliorate racial disparities in health outcomes.

The Brain and Early Experience Study: Protocol for a Prospective Observational Study

BACKGROUND

Children raised in conditions of poverty (or near poverty) are at risk for nonoptimal mental health, educational, and occupational outcomes, many of which may be precipitated by individual differences in executive function (EF) skills that first emerge in early childhood.

OBJECTIVE

The Brain and Early Experience study considers prenatal and postnatal experiences that may mediate the association between poverty and EF skills, including neural substrates. This paper described the study rationale and aims; research design issues, including sample size determination, the recruitment strategy, and participant characteristics; and a summary of developmental assessment points, procedures, and measures used to test the study hypotheses.

METHODS

This is a prospective longitudinal study examining multiple pathways by which poverty influences normative variations in EF skills in early childhood. It is funded by the National Institute of Child Health and Human Development and approved by the institutional review board.

RESULTS

Recruitment is complete with a sample of 203 participants, and data collection is expected to continue from September 2018 to February 2024. Of those recruited as low socioeconomic status (SES), 71% (55/78) reported income-to-needs (ITN) ratios of <2.0, and 35% (27/78) reported ITN ratios of <1.0. Among participants recruited into the not-low SES stratum, only 8.8% (11/125) reported ITN ratios of <2.0, and no participant reported ITN ratios of <1.0. The average ITN ratio for participants recruited into the low-income stratum was significantly lower than the average for the high-income recruitment cell (P<.001). Comparable recruitment outcomes were observed for both Black and non-Black families. Overall, the sample has adequate diversity for testing proposed hypotheses, with 13.3% (27/203) of participants reporting ITN ratios of <1 and >32.5% (66/203) reporting ratios of <2.0.

CONCLUSIONS

Preliminary results indicate that the recruitment strategy for maximizing variation in family SES was successful, including variation within race. The findings of this study will help elucidate the complex interplay between prenatal and postnatal risk factors affecting critical neurocognitive developmental outcomes in early childhood.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/34854.

Effectiveness of behavioral sleep interventions on children's and mothers' sleep quality and maternal depression: a systematic review and meta-analysis

This systematic review and meta-analysis was conducted to investigate the effectiveness of behavioral sleep interventions (BSIs) on the number of child night awakenings, and maternal sleep quality and depression. The search followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA) using PubMed, CINAHL, Cochrane, and EMBASE databases and retrieved studies published until April 2021. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for child sleep problems, and the mean differences (MD) and 95% CI for the number of child night awakenings, and maternal sleep quality and depression. Ten studies of 1628 initial searched were included in the final analysis. Two of the 10 studies were divided into two subgroups by participants and intervention type; thus, 12 subgroups were included in the meta-analysis. BSIs significantly reduced child sleep problems (OR 0.51; 95% CI 0.37-0.69) and improved maternal sleep quality (MD - 1.30; 95% CI - 1.82 to - 0.77) in the intervention group. There were no significant differences in the number of child night awakenings and maternal depression between the two groups. More RCTs to examine the effect of BSIs considering children's age, duration of intervention, and outcome measuring time points are needed.

Prospective Associations Between Fathers' Engagement in Infant Caregiving and Their Weight-Related Behaviors and Mental Health

Fathers’ engagement in infant caregiving is linked with positive social, emotional, and developmental outcomes in children; however, its relationship with fathers’ own health is largely unknown. This longitudinal study examined associations between fathers’ caregiving engagement with their 6-month-old infants and their physical activity, sugar-sweetened beverage (SSB) consumption, nighttime sleep duration, and depressive symptoms 6 months later when infants were 12 months old. Participants were 143 fathers of infants (62.7% non-Hispanic White, 82.3% with a bachelor’s degree). Fathers reported their frequency of engagement in seven caregiving activities when infants were 6 months old. Fathers’ physical activity, SSB consumption, nighttime sleep duration, and depressive symptoms were assessed when infants were 6 and 12 months old. Multivariate logistic regression analysis was used to assess if fathers who reported higher infant caregiving at 6 months had more positive health outcomes at 12 months, controlling for fathers’ age, race/ethnicity, education, employment, household income, and the outcome at 6 months. Fathers who reported higher caregiving engagement when infants were 6 months old had increased odds of being sufficiently physically active 6 months later (unadjusted odds ratio [OR] = 1.19, 95% confidence interval [CI] = [1.00, 1.41]; adjusted OR = 1.47, 95% CI = [1.11, 1.96]). No links were identified between fathers’ caregiving engagement and their SSB consumption, nighttime sleep duration, or depressive symptoms. In summary, fathers’ engagement in infant caregiving may be beneficial to their physical activity in the first year after birth. There was insufficient evidence in this study that the benefits of caregiving engagement were experienced broadly across multiple health outcomes.

Correlates of a caregiver-reported child sleep problem and variation by community disadvantage

BACKGROUND

Previous studies of sleep patterns and perceived problems in early childhood indicate variation by family socioeconomic status. The purpose of this study was to examine variation in correlates of a caregiver-perceived child sleep problem across and within levels of community disadvantage in a large US sample.

METHODS

Caregivers of 14,980 young children (ages 0-35.9 months) in the US completed the Brief Infant Sleep Questionnaire-Revised (BISQ-R) on the freely and publicly available Johnson's® Bedtime® Baby Sleep App. Zip code was used to identify a Distressed Communities Index (DCI) score, which represents community disadvantage based on neighborhood indicators.

RESULTS

Across all levels of community disadvantage, caregivers who reported greater impact of child sleep on their own sleep, bedtime difficulty, more frequent and longer night wakings, and increased total nighttime sleep were more likely to endorse a child sleep problem. These associations varied by level of community disadvantage. For caregivers living in more disadvantaged communities, impact of child sleep on their own sleep and night wakings were the strongest correlates of endorsing a child sleep problem, whereas for those in more advantaged communities the impact of child sleep on their own sleep and night wakings as well as additional aspects of sleep health, such as short sleep duration, were associated with endorsement of a child sleep problem.

CONCLUSIONS

Findings suggest that families living in more distressed communities are most likely to identify the impact of child sleep on their own sleep and night wakings in reporting a child sleep problem, whereas those from more prosperous communities consider these factors as well as other sleep parameters, including sleep duration. Clinicians should consider expanding screening questions for child sleep problems to include the perceived impact on caregiver sleep.

Longitudinal association of actigraphy-assessed sleep with physical growth in the first 6 months of life

STUDY OBJECTIVES

Suboptimal sleep is associated with obesity and its sequelae in children and adults. However, few studies have examined the association between sleep and physical growth in infants who experience rapid changes in sleep/wake patterns. We examined the longitudinal association of changes in objectively assessed sleep/wake patterns with changes in growth between ages 1 and 6 months.

METHODS

We studied 298 full-term infants in the longitudinal Rise & SHINE cohort study. Changes from 1 and 6 months in nighttime sleep duration, wake after sleep onset (WASO), and number of waking bouts ≥5 min were assessed using ankle actigraphy. Overweight was defined as age- and sex-specific weight for length ≥95th percentile. Generalized estimating equation analyses adjusted for infants' and mothers' characteristics.

RESULTS

The mean (SD) birth weight was 3.4 (0.4) kg; 48.7% were boys. In multivariable adjusted models, each 1-h increase in nighttime sleep duration between months 1 and 6 was associated with a 26% decrease in the odds of overweight from 1 to 6 months (odds ratio [OR] = 0.74; 95% confidence interval [CI, 0.56, 0.98]). Each 1-unit decrease in number of waking bouts was associated with a 16% decrease in the odds of overweight (OR = 0.84; 95% CI [0.72, 0.98]). Changes in WASO were not associated with the odds of overweight.

CONCLUSIONS

Greater increases in nighttime sleep duration and more consolidation of nighttime sleep were associated with lower odds of overweight from 1 to 6 months. Adverse sleep patterns as early as infancy may contribute to excess adiposity.

Later sleep timing predicts accelerated summer weight gain among elementary school children: a prospective observational study

OBJECTIVES AND BACKGROUND

Social demands of the school-year and summer environment may affect children's sleep patterns and circadian rhythms during these periods. The current study examined differences in children's sleep and circadian-related behaviors during the school-year and summer and explored the association between sleep and circadian parameters and change in body mass index (BMI) during these time periods.

METHODS

This was a prospective observational study with 119 children ages 5 to 8 years with three sequential BMI assessments: early school-year (fall), late school-year (spring), and beginning of the following school-year in Houston, Texas, USA. Sleep midpoint, sleep duration, variability of sleep midpoint, physical activity, and light exposure were estimated using wrist-worn accelerometry during the school-year (fall) and summer. To examine the effect of sleep parameters, physical activity level, and light exposure on change in BMI, growth curve modeling was conducted controlling for age, race, sex, and chronotype.

RESULTS

Children's sleep midpoint shifted later by an average of 1.5 h during summer compared to the school-year. After controlling for covariates, later sleep midpoints predicted larger increases in BMI during summer, (γ = .0004, p = .03), but not during the school-year. Sleep duration, sleep midpoint variability, physical activity levels, and sedentary behavior were not associated with change in BMI during the school-year or summer. Females tended to increase their BMI at a faster rate during summer compared to males, γ = .06, p = .049. Greater amounts of outdoor light exposure (γ = -.01, p = .02) predicted smaller increases in school-year BMI.

CONCLUSIONS

Obesity prevention interventions may need to target different behaviors depending on whether children are in or out of school. Promotion of outdoor time during the school-year and earlier sleep times during the summer may be effective obesity prevention strategies during these respective times.