Sleep and Adiposity in Preadolescent Children: The Importance of Social Jetlag

The effect of sleep disorders, school jet lag, and anxiety in students 8-10 years of age on traumatic dental injuries

BACKGROUND/AIM

Traumatic dental injuries (TDI) constitute a public health problem. The aim of the present study was to investigate whether sleep disorders, school jet lag, and anxiety are associated with TDI in schoolchildren 8-10 years of age.

METHODS

An analytical, cross-sectional study was conducted with 739 pairs of parents/guardians and children enrolled in public and private schools. The parents/guardians answered a socioeconomic questionnaire, the Sleep Disturbance Scale for Children, Circadian Energy Scale, and Revised Children's Manifest Anxiety Scale. Four examiners underwent calibration exercises for the diagnosis of TDI (K > 0.80) using the criteria proposed by Andreasen (2007). A directed acyclic graph was used for the formulation of the theoretical model and statistical adjustments. Unadjusted and adjusted robust binary logistic regression analyses were performed (α = 5%).

RESULTS

The prevalence of TDI was 16.2%. The following variables remained associated with the outcome in the final model: family income less than or equal to the minimum monthly wage (OR = 1.77; 95% CI: 1.09-2.88; p = .02), child's height >137.6 cm (OR = 1.68; 95% CI: 1.06-2.64; p = .02), the occurrence of school jet lag (OR = 2.12; 95% CI: 1.27-3.53; p = .004), anxiety (OR = 1.77; 95% CI: 1.04-3.00; p = .04) and sleep disorders (OR = 1.63; 95% CI: 1.38-1.93; p = .05).

CONCLUSION

Children from families with a lower income, taller children, those with school jet lag, those with anxiety and those with sleep disorders had a greater occurrence of TDI.

Understanding Accelerated Summer Body Mass Index Gain by Tracking Changes in Children's Height, Weight, and Body Mass Index Throughout the Year

Background: Drivers of summer body mass index (BMI) gain in children remain unclear. The Circadian and Circannual Rhythm Model (CCRM) posits summer BMI gain is biologically driven, while the Structured Days Hypothesis (SDH) proposes it is driven by reduced structure. Objectives: Identify the mechanisms driving children's seasonal BMI gain through the CCRM and SDH. Methods: Children's (N = 147, mean age = 8.2 years) height and weight were measured monthly during the school year, and once in summer (July-August). BMI z-score (zBMI) was calculated using CDC growth charts. Behaviors were measured once per season. Mixed methods regression estimated monthly percent change in children's height (%HΔ), weight (%WΔ), and monthly zBMI for school year vs. summer vacation, seasonally, and during school months with no breaks vs. school months with a break ≥1 week. Results: School year vs. summer vacation analyses showed accelerations in children's %WΔ (Δ = 0.9, Standard Error (SE) = 0.1 vs. Δ = 1.4, SE = 0.1) and zBMI (Δ = -0.01, SE = 0.01 vs. Δ = 0.04, SE = 0.3) during summer vacation, but %HΔ remained relatively constant during summer vacation compared with school (Δ = 0.3, SE = 0.0 vs. Δ = 0.4, SE = 0.1). Seasonal analyses showed summer had the greatest %WΔ (Δ = 1.8, SE = 0.4) and zBMI change (Δ = 0.05, SE = 0.03) while %HΔ was relatively constant across seasons. Compared with school months without a break, months with a break showed higher %WΔ (Δ = 0.7, SE = 0.1 vs. Δ = 1.6, SE = 0.2) and zBMI change (Δ = -0.03, SE = 0.01 vs. Δ = 0.04, SE = 0.01), but %HΔ was constant (Δ = 0.4, SE = 0.0 vs. Δ = 0.3, SE = 0.1). Fluctuations in sleep timing and screen time may explain these changes. Conclusions: Evidence for both the CCRM and SDH was identified but the SDH may more fully explain BMI gain. Interventions targeting consistent sleep and reduced screen time during breaks from school may be warranted no matter the season.

Social jetlag and obesity: A systematic review and meta-analysis

Social jetlag, the weekly variation in sleep timing, is proposed to contribute to increased obesity risk, potentially because of the misalignment of behavioral cycles relative to the endogenous circadian timing system. This systematic review and meta-analysis aim to determine the association between social jetlag and adiposity-related measures using observational studies. We reviewed 477 references, of which 43 studies met inclusion criteria with a total sample size of 231,648. There was a positive association between social jetlag and body mass index (correlation coefficient [r]: 0.12; 95%CI, 0.07, 0.17; P < 0.001; I2  = 94.99%), fat mass (r: 0.10; 95%CI, 0.05, 0.15; P < 0.001; I2  = 0.00%), fat mass index (fat mass divided by height in meter squared, β: 0.14 kg/m2 ; 95%CI, 0.05, 0.23; P < 0.001; I2  = 56.50%), percent of body fat (r: 0.37; 95%CI, 0.33, 0.41; P < 0.001; I2  = 96.17%), waist circumference (r: 0.15; 95%CI, 0.06, 0.24; P = 0.001; I2  = 90.83%), and the risk of having overweight/obesity (odds ratio: 1.20; 95%CI, 1.02, 1.140; P = 0.039; I2  = 98.25%). Social jetlag is positively and consistently associated with multiple obesity-related anthropometric measures. Further studies are needed to test causality, underlying mechanisms, and whether obesity interventions based on increasing regularity of the sleep/wake cycle can aid in the battle against the obesity pandemic.

Comparison of actigraphy-measured and parent-reported sleep in association with weight status among preschool children

This study compared weekday and weekend actigraphy-measured and parent-reported sleep in relation to weight status among preschool-aged children. Participants were 3-6 years old preschoolers from the cross-sectional DAGIS-study with sleep data for ≥2 weekday and ≥2 weekend nights. Parents-reported sleep onset and wake-up times were gathered alongside 24 h hip-worn actigraphy. An unsupervised Hidden-Markov Model algorithm provided actigraphy-measured night time sleep without the guidance of reported sleep times. Waist-to-height ratio and age-and-sex-specific body mass index characterised weight status. Comparison of methods were assessed with consistency in quintile divisions and Spearman correlations. Associations between sleep and weight status were assessed with adjusted regression models. Participants included 638 children (49% girls) with a mean ± SD age of 4.76 ± 0.89. On weekdays, 98%-99% of actigraphy-measured and parent-reported sleep estimates were classified in the same or adjacent quintile and were strongly correlated (rs  = 0.79-0.85, p < 0.001). On weekends, 84%-98% of actigraphy-measured and parent-reported sleep estimates were respectively classified and correlations were moderate to strong (rs  = 0.62-0.86, p < 0.001). Compared with actigraphy-measured sleep, parent-reported sleep had consistently earlier onset, later wake-up, and greater duration. Earlier actigraphy-measured weekday sleep onset and midpoint were associated with a higher body mass index (respective β-estimates: -0.63, p < 0.01 and -0.75, p < 0.01) and waist-to-height ratio (-0.004, p = 0.03 and -0.01, p = 0.02). Though the sleep estimation methods were consistent and correlated, actigraphy measures should be favoured as they are more objective and sensitive to identifying associations between sleep timing and weight status compared with parent reports.

The relationship between multiple sleep dimensions and obesity in adolescents: A systematic review

Sleep is an involuntary behaviour, biologically fundamental to survival and wellbeing. However, sleep is increasingly neglected, with significant health implications. Recent research has identified associations between sleep duration, quality, timing and risk of overweight/obesity in children and adults. The aim of this review was to systematically identify and examine research that investigates the relationships between multiple objective and subjective sleep outcomes and objective adiposity measures in adolescents. A systematic review of literature, published to December 2022, was conducted using ten bibliographic databases. Search terms included objective and subjective sleep/circadian rhythm outcomes, objective adiposity measurements, and adolescents aged 8-18 years. Eighty-nine studies were included in the final review. Sleep outcomes were synthesized into three sleep domains: pre-sleep, during sleep and post-sleep outcomes. In summary, pre-sleep outcomes (including poor sleep hygiene, later chronotype and increased variability and later sleep timings) and increased sleep disturbance are consistently significantly associated with increased obesity and adiposity in adolescents. The relationship between during-sleep outcomes (sleep quality and efficiency) with adiposity and obesity measures was mixed. These findings suggest that adapting an individual's schedule to best suit chronotype preference and improving sleep hygiene, including a consistent bedtime routine, could reduce adiposity and obesity in adolescents.

Associations of social jetlag with physical activity and sedentary behaviour in children and adolescents: A systematic review and meta-analysis

Sleep and daytime movement behaviours occur co-dependently with each other within a finite 24 h day. Sleep parameters other than sleep duration, such as social jetlag and chronotype, have been linked to health problems and unhealthy behaviours among children and adolescents. Given the increasing number of studies examining sleep timing/chronotype and weight-related behaviours, including physical activity and sedentary behaviour, in the past decade, this systematic review and meta-analysis collated and evaluated the evidence on the relationships of social jetlag and chronotype with physical activity and sedentary behaviour among children and adolescents aged 3-17 years. Seven databases were searched on 16 March 2022, and 52 studies were identified as eligible for inclusion, 47 of which were suitable for the meta-analysis. A positive association was found between social jetlag and screen media use (r = 0.14, 95% CI: 0.04-0.24; I2  = 96%; p = 0.008). The morning chronotype was associated with a higher level of physical activity and a lower level of sedentary behaviour than the evening chronotype. No relationship was found between social jetlag and physical activity. The magnitude of heterogeneity among the included studies was high. Further experimental studies are urgently required to understand how circadian preference or misalignment affects activity behaviours. Interventions to promote an active lifestyle in young populations should consider their circadian preference, especially among individuals with the evening chronotype.

Association of Time in Bed, Social Jetlag, and Sleep Disturbances With Cognitive Performance in Children With ADHD

OBJECTIVES

Children with ADHD commonly exhibit sleep disturbances, but there is limited knowledge about how sleep and sleep timing are associated with cognitive dysfunction in children with ADHD.

METHODS

Participants were 350 children aged 5 to 12 years diagnosed with ADHD. Three sleep-related constructs-time in bed, social jetlag (i.e., discrepancy in sleep timing pattern between school nights and weekend nights), and sleep disturbances were measured using a caregiver-report questionnaire. Linear regression models assessed the associations between sleep-related constructs and cognitive performance.

RESULTS

After adjustment for sociodemographic variables, there were few associations between time in bed or sleep disturbances and cognitive performance, however, greater social jetlag was negatively associated with processing speed (β = -.20, 95% CI [-0.35, -0.06]), visually-based reasoning (β = -.13, 95% CI [-0.27, 0.00]), and language-based reasoning (β = -.22, 95% CI [-0.36, -0.08]); all p < .05).

CONCLUSION

Social jetlag, but not time in bed or disturbances, was associated with lower cognitive performance among children with ADHD.

The importance of sleep regularity: a consensus statement of the National Sleep Foundation sleep timing and variability panel

OBJECTIVE

To develop and present consensus findings of the National Sleep Foundation sleep timing and variability panel regarding the impact of sleep timing variability on health and performance.

METHODS

The National Sleep Foundation assembled a panel of sleep and circadian experts to evaluate the scientific evidence and conduct a formal consensus and voting procedure. A systematic literature review was conducted using the NIH National Library of Medicine PubMed database, and panelists voted on the appropriateness of 3 questions using a modified Delphi RAND/UCLA Appropriateness Method with 2 rounds of voting.

RESULTS

The literature search and panel review identified 63 full text publications to inform consensus voting. Panelists achieved consensus on each question: (1) is daily regularity in sleep timing important for (a) health or (b) performance? and (2) when sleep is of insufficient duration during the week (or work days), is catch-up sleep on weekends (or non-work days) important for health? Based on the evidence currently available, panelists agreed to an affirmative response to all 3 questions.

CONCLUSIONS

Consistency of sleep onset and offset timing is important for health, safety, and performance. Nonetheless, when insufficient sleep is obtained during the week/work days, weekend/non-work day catch-up sleep may be beneficial.

From Alert Child to Sleepy Adolescent: Age Trends in Chronotype, Social Jetlag, and Sleep Problems in Youth with Autism

PURPOSE

Developmental changes in sleep in youth with autism spectrum disorder (ASD) are understudied. In non-ASD youth, adolescents exhibit a "night owl chronotype" (i.e., later sleep/wake timing) and social jetlag (i.e., shifts in sleep timing across school nights and weekends), with corresponding sleep problems. The purpose of this study is to evaluate age trends in chronotype, social jetlag, and sleep problems in high-risk youth with ASD.

METHODS

Youth with ASD (N = 171), ages 5-21 years old, were enrolled at the time of admission to specialized psychiatric units. Caregivers reported children's demographic information, habitual sleep timing, and sleep problems. Multivariate analyses evaluated the effect of age on chronotype, social jetlag, and sleep problems and the effects of chronotype and social jetlag on sleep problems. Covariates and moderators included sex, race, verbal ability, autism symptom severity, supplemental melatonin, and pubertal status.

RESULTS

Older age was associated with later chronotype, more social jetlag, fewer sleep anxiety/co-sleeping problems, fewer night waking and parasomnia problems, and more daytime alertness problems. The effect of age on chronotype was stronger for youth with greater social affective symptom severity. Mediation analyses showed that later chronotype statistically mediated the association between age and daytime alertness problems.

CONCLUSIONS

Youth with ASD may exhibit night owl chronotype behavior and social jetlag as they enter adolescence. Shifts toward a later chronotype may be exacerbated by autism severity and may contribute to alertness problems and sleepiness during the day. Chronotype is modifiable and may be leveraged to improve daytime functioning in youth with ASD.

Social jetlag is associated with adverse cardiometabolic latent traits in early adolescence: an observational study

Introduction

Adolescence is marked by physiological and social changes, such as puberty, increased responsibilities and earlier school start times. This often leads to insufficient sleep on school nights and the need to compensate for lost sleep on weekends, causing a misalignment between biological and social times, which has been termed social jetlag (SJL). SJL triggers stress responses and is associated with several negative health outcomes, including higher cardiometabolic risk in adults. In adolescence, however, SJL has only been consistently related to increases in adiposity but its association with other cardiometabolic indicators are unclear.

Method

In a sample of 278 healthy early adolescents (9-15 years of age; 168 girls) we investigated: 1) whether self-reported SJL is associated (using path analyses) with a cardiometabolic status latent factor obtained by testing the best fitting model via confirmatory factor analyses from an initial set of eight indicators [body mass index (BMI), waist/height ratio, triglyceride concentration, diastolic and systolic blood pressure, glycated hemoglobin, total cholesterol/high-density lipoprotein ratio (chol/HDL), and % body fat]; and 2) whether age and/or pubertal status influence the association between SJL and cardiometabolic status.

Result

We found that, for girls, higher SJL was associated with more adverse cardiometabolic latent scores (the shared variance of BMI, waist/height ratio, chol/HDL and systolic blood pressure, which had acceptable model fit indices). However, the role of age and pubertal status in this association was unclear for both sexes.

Discussion

SJL was associated with adverse cardiometabolic latent traits beyond increases in adiposity in this observational study in early female adolescents. Because disruptions of circadian rhythms are believed to lead to dysregulated energy homeostasis and not vice-versa, our findings highlight the need for sleep interventions in adolescence to help reduce the global burden of cardiometabolic ill health, especially in girls.

Sleep, 24-hour activity rhythms, and cardiometabolic risk factors in school-age children

STUDY OBJECTIVES

Disturbed sleep and 24-hour activity rhythms are linked to adverse cardiometabolic profiles in adults and adolescents, and these associations may originate in early life. We aimed to study associations of sleep and 24-hour rhythms with cardiometabolic risk factors in school-age children.

METHODS

This cross-sectional population-based study comprised 894 children aged 8-11 years from the Generation R Study. Sleep (duration, efficiency, number of awakenings, and time awake after sleep onset) and 24-hour activity rhythms (social jet lag, interdaily stability, and intradaily variability) were assessed using triaxial wrist actigraphy for 9 consecutive nights. Cardiometabolic risk factors included adiposity (body mass index Z-score, fat mass index using dual-energy X-ray absorptiometry, and visceral fat mass and liver fat fraction using magnetic resonance imaging), blood pressure, and blood markers (glucose, insulin, and lipids). We adjusted for season, age, sociodemographics, and lifestyle factors.

RESULTS

Each increase in interquartile range of nightly awakenings (2 times) was associated with -0.12 standard deviation (95% confidence interval: -0.21, -0.04) lower body mass index and 0.15 mmol/L (0.10, 0.21) higher glucose. Among boys, an increase in interquartile range of intradaily variability (0.12) was associated with higher fat mass index (+0.07 kg/m2; 95% confidence interval: 0.03, 0.11) and visceral FM (+0.08 g; 95% confidence interval: 0.02, 0.15). We observed no associations with blood pressure or clustering of cardiometabolic risk factors.

CONCLUSIONS

Already at school age, greater fragmentation of the 24-hour activity rhythm is associated with general and organ adiposity. In contrast, more nightly awakenings were associated with lower body mass index. Future research should bring clarity to these disparate observations in order to create potential targets for obesity prevention programs.

CITATION

Beunders VAA, Koopman-Verhoeff ME, Vermeulen MJ, et al. Sleep, 24-hour activity rhythms, and cardiometabolic risk factors in school-age children. J Clin Sleep Med. 2023;19(7):1219-1229.

The relationship between sleep duration and health among Pacific adolescents within New Zealand: Findings from the Pacific Islands families study

OBJECTIVE

Sleep insufficiency is bi-directionally associated with adverse behavioural, physical and mental health outcomes in paediatric populations. However, little is known about the degree of sleep insufficiency and its effect on Pacific adolescents' wellbeing.

METHODS

A cross-sectional study of 14-year old Pacific adolescents nested within a longitudinal birth cohort was conducted. Self-reported sleep duration was related to sentinel physical, mental, and risk taking behaviour measures in crude and adjusted logistic regression models. Complete case and multiple imputed analyses were conducted.

RESULTS

916 Pacific adolescents were eligible, with a mean age of 14.2 years. Valid sleep data were available from 828 (90.4%) participants, with only 220 (26.6%) meeting the recommended amount of sleep. Insufficient sleep duration was associated with significantly higher rates of depressive symptoms and risk taking behaviours. In multiple imputed analyses, increased body mass index was also significantly related.

CONCLUSIONS

Sleep insufficiency is ubiquitous among Pacific adolescents and associated with negative impacts on their health and wellbeing.

IMPLICATIONS FOR PUBLIC HEALTH

Insufficient sleep duration is amenable to change. Bespoke, culturally responsive public health strategies that draw attention to the importance of positive sleep practices are needed. Particularly, among adolescents who are at risk of experiencing the greatest burden of insufficient sleep.

A Cross-Sectional Investigation of Preadolescent Cardiometabolic Health: Associations with Fitness, Physical Activity, Sedentary Behavior, Nutrition, and Sleep

BACKGROUND

Cardiometabolic disease (CMD) risk often begins early in life. Healthy lifestyle behaviors can mitigate risk, but the optimal combination of behaviors has not been determined. This cross-sectional study simultaneously examined the associations between lifestyle factors (fitness, activity behaviors, and dietary patterns) and CMD risk in preadolescent children.

METHODS

1480 New Zealand children aged 8-10 years were recruited. Participants included 316 preadolescents (50% female, age: 9.5 ± 1.1 years, BMI: 17.9 ± 3.3 kg/m²). Fitness (cardiorespiratory fitness [CRF], muscular fitness), activity behaviors (physical activity, sedentary, sleep), and dietary patterns were measured. Factor analysis was used to derive a CMD risk score from 13 variables (adiposity, peripheral and central hemodynamics, glycemic control, and blood lipids).

RESULTS

Only CRF (β = -0.45, p < 0.001) and sedentary time (β = 0.12, p = 0.019) were associated with the CMD risk score in the adjusted multivariable analysis. CRF was found to be nonlinear (VO₂ max ≤ ≈42 mL/kg/min associated with higher CMD risk score), and thus a CRF polynomial term was added, which was also associated (β = 0.19, p < 0.001) with the CMD risk score. Significant associations were not found with sleep or dietary variables.

CONCLUSION

The findings indicate that increasing CRF and decreasing sedentary behavior may be important public health targets in preadolescent children.

The association between social jetlag and parameters of metabolic syndrome and type 2 diabetes: a systematic review and meta‐analysis

This study aims to determine the association between social jetlag and parameters of metabolic syndrome and type 2 diabetes (T2D) in a systematic review and meta-analysis. A systematic literature search was conducted in PubMed/Embase/Scopus until May 2022. Included studies described an association between social jetlag and parameters of the metabolic syndrome and/or T2D, were available full text and written in English or Dutch. Data extraction and quality assessment were performed on pre-piloted forms independently by two reviewers. Results were meta-analysed using random-effects analysis. A total of 6,290 titles/abstracts were screened, 176 papers were read full-text, 68 studies were included. Three studies were rated as low quality, 27 were moderate, and 38 were high quality. High quality studies showed that having social jetlag compared to no social jetlag was significantly associated with higher body mass index in 20 studies (0.49 kg/m² , 95% confidence interval [CI] 0.21-0.77; I²  = 100%), higher waist circumference in seven studies (1.11 cm, 95% CI 0.42-1.80; I²  = 25%), higher systolic blood pressure in 10 studies (0.37 mmHg, 95% CI 0.00-0.74; I²  = 94%) and higher glycated haemoglobin in 12 studies (0.42%, 95% CI 0.12- 0.72; I²  = 100%). No statistically significant associations were found for obesity, abdominal obesity, high- and low-density lipoprotein levels, cholesterol, triglycerides, diastolic blood pressure, hypertension, fasting glucose, homeostatic model assessment for insulin resistance, metabolic syndrome or T2D. Sensitivity analyses did not reduce heterogeneity. Despite substantial heterogeneity, social jetlag is associated with certain parameters of the metabolic syndrome and T2D, but not with prevalent metabolic syndrome or T2D. These findings should be interpreted with caution as the level of evidence is low and mostly based on cross-sectional data. Longitudinal studies are needed to further assess the direction of causality.

Adiposity in preadolescent children: Associations with cardiorespiratory fitness

Lifestyle factors contribute to childhood obesity risk, however it is unclear which lifestyle factors are most strongly associated with childhood obesity. The purpose of this cross-sectional study was to simultaneously investigate the associations among dietary patterns, activity behaviors, and physical fitness with adiposity (body fat %, fat mass, body mass index [BMI], and waist to hip ratio) in preadolescent children. Preadolescent children (N = 392, 50% female, age: 9.5 ± 1.1year, BMI: 17.9 ± 3.3 kg/m2) were recruited. Body fat (%) and fat mass (kg) were measured with bioelectrical impedance analysis. Cardiorespiratory fitness (VO2 max), muscular strength (hand-grip strength), activity, sleep, and dietary pattern was assessed. Multivariable analysis revealed that cardiorespiratory fitness associated most strongly with all four indicators of adiposity (body fat (%) (β = -0.2; p < .001), fat mass (β = -0.2; p < .001), BMI (β = -0.1; p < .001) and waist to hip ratio (β = -0.2; p < .001). Additionally, fruit and vegetable consumption patterns were associated with body fat percentage, but the association was negligible (β = 0.1; p = 0.015). Therefore, future interventions should aim to promote the use of cardiorespiratory fitness as a means of reducing the obesity epidemic in children.

Relationship of 24-Hour Movement Behaviors with Weight Status and Body Composition in Chinese Primary School Children: A Cross-Sectional Study

24 h movement behaviors, specifically physical activity (PA), sedentary behavior, and sleep, play a crucial role in the prevention and intervention of childhood obesity. This study aimed to examine the association of 24 h movement behaviors with weight status and body composition among Chinese primary school children. Using a random stratified sampling, 978 eligible participants (9.1 ± 1.4 years, 53.2% boys) were recruited from 1 May to 15 July 2021. Demographics included children’s age, gender, grade, parents’ education level, and household income. Movement behaviors were measured by validated self-reported scales. Weight status and body composition (percent of body fat, PBF; fat-free mass, FFM; skeletal muscle mass, SMM) were measured objectively. Results indicated that participants who were younger, boys, and at lower grade showed higher guidelines adherence. PA was inversely associated with PBF, while screen time (ST) was positively associated with overweight/obesity risk and FFM. Sleep showed no association with any health indicators. Meeting the behavioral guidelines was associated with better weight status and lower PBF, yet not with FFM and SMM. Interventions to improve the Children’s weight status and PBF should involve enhancing their overall movement behaviors and considering their demographic differences. More research on examining the association of movement guidelines adherence with body composition indicators is needed.

Sleeping through COVID-19: a longitudinal comparison of 2019 and 2020 infant auto-videosomnography metrics

BACKGROUND

With the outbreak of the COVID-19 pandemic, pediatric experts called attention to the potential adverse effects of living restrictions (e.g., lockdown) on child well-being, but at the same time- acknowledged their possible benefits. To date, only few data-driven reports have been published on child sleep during COVID-19, and all have been based on parent- or self-reports. This study used auto-videosomnography to capture the effects of COVID-19 stay-at-home orders imposed in the USA on objectively measured infant sleep.

METHODS

Auto-videosomnography metrics of infants assessed nightly between January and May 2020 were compared with metrics of an equivalent infant cohort, assessed in the corresponding 2019 period. A total of 610 infants (50.7% girls) aged 6-18 months (M = 11.8, SD = 3.6) were included, with 71,472 analyzed nights. Multilevel models were applied to assess differences between 2019 and 2020 infant sleep pre- and during-lockdown.

RESULTS

Whereas infant cohorts were equivalent in demographic and January-March/April sleep characteristics, during the 2020 lockdown infants had longer nighttime sleep durations (M_difference  = 11.0 min, p = .01), later morning rise times (M_difference  = 9.5 min, p = .008), and later out-of-crib times (M_difference  = 12.3 min, p < .0001), compared to the equivalent 2019 period. In addition, weekday-weekend differences in sleep onset and midpoint times were diminished during 2020 home-confinement compared to the equivalent 2019 period (2019: M_difference  = 5.5 min, p < .0001; M_difference  = 4.5 min, p < .0001; 2020: M_difference  = 2.3 min, p = .01; M_difference  = 3.1 min, p < .0001, respectively).

CONCLUSIONS

Notwithstanding the negative implications of COVID-19 living restrictions in other domains, our findings indicate that there might be a silver lining-in promoting longer and more consistent infant sleep. These benefits should be considered in determining policy for the current and future pandemics.

Association of accelerometry-derived social jetlag and sleep with temperament in children less than 6 years of age

STUDY OBJECTIVES

Social jetlag (SJL) measures the discrepancy between circadian and social clocks. Using accelerometry-derived data, our objective was to assess the prevalence of SJL in young healthy children and determine the association of SJL and sleep with temperament.

METHODS

Of 117 children participating in TARGet Kids!, a Canadian cohort of healthy preschool-aged children, 78 children (39 girls (50%)); mean age [SD]: 35.1[20.5] months) were included. Sleep was measured objectively using accelerometry. Temperament dimensions (surgency, negative affectivity, and effortful control) were assessed with the very short forms of Rothbart's child and infant behavior questionnaires. We examined associations of SJL and sleep with temperament using multivariable linear regression models adjusted for sex, age, ethnicity, and preschool/daycare attendance.

RESULTS

20 out of 78 (25.6%) experienced SJL of greater than 30 minutes. SJL was greater in children who attended preschool/daycare compared with children who did not (26.3[18.8]min vs. 17.6[14.8]min; p<0.05). There was no evidence of an association between SJL and any temperament dimension. We found evidence of an association between increased sleep duration and increased negative affectivity scores (longer 24h sleep (ß:0.347, 95% CI:0.182,0.512, p<0.0001); longer nighttime sleep duration (ß:0.413, 95% CI:0.163,0.663, p=0.002)).

CONCLUSIONS

In our cohort, 1 in 4 preschool-aged children experienced SJL. Increased sleep duration was associated with increased negative affect, which could have implications for children developing internalizing behavior such as depression or low-self-esteem. We found that sleep duration, but not SJL, was associated with temperament and may impact daytime behavior of young children.

Examining adolescents' obesogenic behaviors on structured days: a systematic review and meta-analysis

BACKGROUND

The structured days hypothesis posits that 'structured days' (i.e., days with pre-planned, segmented, and adult-supervised environments) reduce youth obesogenic behaviors. Structured days may be especially important for adolescents', as adolescence (12-19 years) is a period of developmental milestones and increased autonomy. Therefore, the objective of this systematic review and meta-analysis is to evaluate the relationship between structured days and adolescents' obesogenic behaviors (i.e., physical activity, diet, screen time, and/or sleep).

METHODS

From February to April of 2020, four databases (i.e., Embase, PubMed, Web of Science, and PsychINfo) were searched for cross-sectional, longitudinal, and intervention (i.e., baseline data only) studies reporting obesogenic behaviors on more structured versus less structured days (i.e., weekday versus weekend or school year versus summer/holiday).

RESULTS

A total of 42,878 unique titles and abstracts were screened with 2767 full-text articles retrieved. After review of full-text articles, 296 studies were identified (sleep k = 147, physical activity k = 88, screen time k = 81, diet k = 8). Most studies were conducted in North America, Europe & Central Asia, or East Asia & the Pacific used self-report measures and compared school days to weekend days. Meta-analyses indicated that adolescents' physical activity (standardized mean difference [SMD] = -0.25 [95%CI - 0.48, -0.03]) and screen time (SMD = -0.48 [95%CI - 0.66, -0.29]) were less healthy on less structured days. Differences did not reach statistical significance for sleep (SMD = -0.23 [95%CI - 0.48, 0.02]) and diet (SMD = -0.13 [95%CI - 0.77, 0.51]), however, sleep timing (SMD = -1.05 [95%CI - 1.31, -0.79]) and diet quantity (SMD = -0.29 [95%CI - 0.35, -0.23]) were less healthy on less structured days. The review identified studies with large heterogeneity.

CONCLUSIONS

Findings indicate that adolescents' physical activity, screen time, sleep timing, and diet quantity are less healthy on less structured days. Interventions for adolescents to prevent and treat obesity may be more successful if they are designed to target times that are less structured.

Wheel-Running Facilitates Phase Advances in Locomotor and Peripheral Circadian Rhythm in Social Jet Lag Model Mice

The circadian clock maintains our health by controlling physiological functions. Social jet lag is one factor that can disrupt the body clock. This is caused by the difference in sleeping hours between weekdays when we live according to social time and holidays when we live according to our body clock. The body clock can be altered by exercise, nutrition, and stress, and several studies have reported that these factors can be used to improve a disturbed body clock. Here we focused on exercise and examined whether continuous wheel-running could improve the disordered body clock in a mouse model that mimics social jet lag. The results showed that the wheel-running exercise group showed faster synchronization of the onset of activities on weekdays which had been delayed by social jet lag and the results were even more pronounced in the high-fat diet feeding condition. Also, when the expression rhythms of the clock genes were examined, they experienced a sudden time shift in the advance light condition or social jet lag condition, it was found that the wheel-running group had a higher ability to adapt to the advance direction. Thus, it is possible that the effective inclusion of exercise in human, especially those who eat high-fat foods, life can improve the disordered body clock in terms of social jet lag.

The Impact of Weekday-to-Weekend Sleep Differences on Health Outcomes among Adolescent Students

The sleep difference between weekdays and weekends can lead to negative physical and mental health outcomes in adolescents. Thus, this study has attempted to analyze the impact of sleep time differences on various health outcomes, using nationally representative panel data. Data from the junior high school student panel of the Korean Children and Youth Panel Survey were analyzed. The sleep difference was defined as the difference between the average sleep duration on weekdays and that on weekends in minutes. A series of mixed effect linear regression models for continuous variables or mixed effect logit regression for binary variables was utilized. Korean adolescent students reported from 96.8 min to 133.2 min of sleep duration difference between weekdays and weekends. After controlling for gender, parent work status, and type of housing, the weekday-to-weekend sleep differences were associated with various health-related outcomes including concentration difficulty, aggression, somatic symptoms, and withdrawal. Additionally, adolescent student life satisfaction was associated with sleep difference. The sleep differences among adolescent students were more associated with mental health-related outcomes and emotional symptoms than with physical health-related outcomes. The appropriate intervention to reduce the sleep difference gap is an important key to improve health in the adolescence period.

Changes in chronotype and social jetlag during adolescence and their association with concurrent changes in BMI-SDS and body composition, in the DONALD Study

BACKGROUND/OBJECTIVES

Adolescence is a critical period for both the development of overweight and the transition toward a later chronotype, often accompanied by an increase in social jetlag. This study assessed whether changes in chronotype and social jetlag, are linked to changes in body composition during adolescence.

SUBJECTS/METHODS

We used data from the DONALD open cohort study, collected between 2014 and 2019, from 213 adolescents (9-17 years at baseline, 45% females) having at least two measures of chronotype and anthropometry (N = 572). Chronotype was assessed with the Munich Chronotype Questionnaire and defined as: midpoint of sleep corrected for sleep-debt (MSFsc) accumulated over the week (later MSFsc represents later chronotype). Social jetlag (SJL) defines the difference between midpoint of sleep during week and weekend. Calculations for Fat Free Mass Index (FFMI [kg/m²)]) and Fat Mass Index (FMI) [kg/m²)]) were based on body fat percentage, weight, and height. To analyze the associations, we used linear mixed-effect regression models. Finally, the total cohort was split into three biologically relevant age groups (cut-off set at <12 years, ≥12 to ≤15 years and >15 years).

RESULTS

Median follow-up was 2.1 years. Overall, change toward a later chronotype was significantly related with an increase in FMI (ß: 0.05, 95% CI: 0.01-0.08). A 1 h increase in social jetlag predicted an increase in BMI-SDS of 0.08 SDS units (95% CI: 0.01-0.14) and in FMI of 0.04 kg/m2 (95% CI: 0.003-0.08). Associations were stronger for the age group ≥12 to ≤15 years (p for interaction: <0.001). No relationship was found with FFMI.

CONCLUSIONS

Changes in MSFsc and SJL during adolescence were associated with concurrent changes in BMI-SDS and FMI. The age ≥12 to ≤15 years appears to be a sensitive period in which chronobiological changes were clearly associated with increasing body fatness.

Recent Advances in Adipose Tissue Dysfunction and Its Role in the Pathogenesis of Non-Alcoholic Fatty Liver Disease

Obesity is a serious ongoing health problem that significantly increases the incidence of nonalcoholic fatty liver disease (NAFLD). During obesity, adipose tissue dysfunction is obvious and characterized by increased fat deposition (adiposity) and chronic low-grade inflammation. The latter has been implicated to critically promote the development and progression of NAFLD, whose advanced form non-alcoholic steatohepatitis (NASH) is considered one of the most common causes of terminal liver diseases. This review summarizes the current knowledge on obesity-related adipose dysfunction and its roles in the pathogenesis of hepatic steatosis and inflammation, as well as liver fibrosis. A better understanding of the crosstalk between adipose tissue and liver under obesity is essential for the development of new and improved preventive and/or therapeutic approaches for managing NAFLD.

Social Jetlag and Cardiometabolic Risk in Preadolescent Children

Objective: Childhood cardiometabolic disease risk (CMD) has been associated with short sleep duration. Its relationship with other aspects of sleep should also be considered, including social jetlag (SJL) which represents the difference between a person's social rhythms and circadian clock. This study investigated whether childhood CMD risk is associated with sleep duration, sleep disturbances, and SJL.

Study Design: The observational study included 332 children aged 8–10 years (48.5% female). The three independent variables were sleep duration, sleep disturbances, and SJL. SJL was calculated as the variation in hours between the midpoint of sleep during free (weekend) days and work/school days. Eleven cardiometabolic biomarkers were measured, including central blood pressure, lipids, glycated hemoglobin, arterial wave reflection, and glucose. Underlying CMD risk factors were identified using factor analysis.

Results: Four underlying CMD risk factors were identified using factor analysis: blood pressure, cholesterol, vascular health, and carbohydrate metabolism. Neither sleep disturbances nor sleep duration were significantly associated with any of the four CMD factors following adjustments to potential confounders. However, SJL was significantly linked to vascular health (p = 0.027) and cholesterol (p = 0.025).

Conclusion: These findings suggest that SJL may be a significant and measurable public health target for offsetting negative CMD trajectories in children. Further studies are required to determine biological plausibility.

Obesogenic Behaviors of Rural Children on School and Nonschool Days

Background: Children living in rural areas are at increased risk of overweight and obesity compared with their urban-dwelling counterparts. The purpose of this study was to provide preliminary evidence of rural children's obesogenic behaviors (e.g., activity, sedentary behaviors, sleep, and diet) during school days, nonschool weekdays, and weekend days. Methods: A repeated measures 14-day observational study was conducted early March 2020. Children (n = 54, 92% 6-11 years old; 66% female; 98% non-Hispanic white; 22% overweight or obese) wore accelerometers on the nondominant wrist for 24 hours/day for 14 consecutive days to capture moderate-to-vigorous physical activity (MVPA), sedentary time, and sleep. Parents completed diaries to report daily activities, diet, and screen time of their child each day. Mixed effect models compared behaviors between school days, nonschool weekdays, and weekend days. Results: Children accumulated +16 additional minutes/day of MVPA (95% confidence interval, CI: +10 to +23 minutes/day), reduced sedentary time (-68 minutes/day, 95% CI: -84 to -51 minutes/day), and reduced screen time (-99 minutes/day; 95% CI: -117 to -81 minutes/day) on school days vs. nonschool weekdays. Similar patterns were observed on school weekdays days vs. weekend days, and on nonschool days when children attended a structured program vs. days they did not attend. Minimal differences were observed in reported consumption of food groups across different days. Conclusions: Preliminary evidence suggests rural children display multiple unfavorable obesogenic behaviors on days when they do not attend school or other structured programs. Future interventions targeting obesogenic behaviors of rural children may want to target times when rural children are not engaged in school and "school-like" environments.

Social jetlag is associated with obesity-related outcomes in 9-11-year-old children, independent of other sleep characteristics

INTRODUCTION

Social jetlag has been reported to predict obesity-related indices, independent of sleep duration, with associations in female adolescents but not males. However, such sex-specific relationships have not been investigated in pre-adolescents.

OBJECTIVES

To examine: (i) the relationships between sleep characteristics, including social jetlag, and obesity-related outcomes during childhood, and (ii) whether these relationships are moderated by sex.

METHODS

This cross-sectional study included 381 children aged 9-11 years (49.6% female). Average sleep duration, social jetlag, and physical activity were assessed via wrist-worn accelerometry. Sleep disturbances were quantified from the Children's Sleep Habits Questionnaire. Obesity-related outcomes included age-specific body mass index Z-scores (zBMI) and waist-to-height ratio. Additionally % fat, total fat mass, and fat mass index were assessed via bioelectrical impedance analysis. Linear mixed models that nested children within schools were used to identify relationships among sleep characteristics and obesity-related outcomes.

RESULTS

Positive associations between social jetlag with zBMI, % fat, and fat mass index were seen in univariable and unadjusted multivariable analyses. Following adjustments for known confounders, social jetlag remained significantly associated with zBMI (β = 0.12, p = 0.013). Simple slopes suggested a positive association in girls (β = 0.19, p = 0.006) but not in boys (β = 0.03, p = 0.703).

CONCLUSIONS

Obesity prevention efforts, particularly in girls, may benefit from targeted approaches to improving the consistency of sleep timing in youth.

Influence of the practice of sports, sleep disorders, and habits on probable sleep bruxism in children with mixed dentition

OBJECTIVE

Investigate the association between sleep disorders and probable sleep bruxism (SB) in children eight to ten years of age.

METHODS

A cross-sectional study was conducted with 739 schoolchildren in Brazil. Parents/guardians answered a sociodemographic questionnaire, the sleep disturbance scale for children, and the Circadian Energy Scale. Parafunctional habits were evaluated using the Nordic Orofacial Test-Screening. Multivariate logistic regression was performed (α = 5%), and a directed acyclic graph was used in the statistical model.

RESULTS

The prevalence of probable SB was 9.1% and 58.6% of the children had sleep disorders. In the final model, having unmarried parents/guardians (OR = 1.98; 95% CI: 1.07-3.65), exhibiting parafunctional habits (OR = 2.02; CI: 1.01-4.06), not practicing sports (OR = 1.92; CI: 1.04-3.54), sleep-wake transition disorders (SWTD) (OR = 2.01; 95%CI: 1.12-3.62), and excessive daytime sleepiness (EDS) (OR = 2.17; 95%CI: 1.11-4.29) were significant associated with probable SB.

CONCLUSION

The occurrence of probable sleep bruxism was influenced by the marital status of the parents/guardians, parafunctional habits, the non-practice of sports, and sleep disturbance (SWTD and EDS). This research contributes to the planning of public policies that include educational regimens at school to prevent sleep disorders and favor the reduction in sleep bruxism prevalence.

Dynamics of sleep, sedentary behavior, and moderate-to-vigorous physical activity on school versus nonschool days

STUDY OBJECTIVES

Studies examining time-use activity behaviors (sleep, sedentary behavior, and physical activity) on school days compared with nonschool days have examined these behaviors independently, ignoring their interrelated nature, limiting our ability to optimize the health benefits of these behaviors. This study examines the associations of school-day (vs. nonschool day) with time-use activity behaviors.

METHODS

Time series data (6,642 days) from Fitbits (Charge-2) were collected (n = 196, 53% female, 5-10 years). We used a variable-centered dynamic structural equation modeling approach to estimate day-to-day associations of time-use activity behaviors on school days for each child. We then used person-centered cluster analyses to group individuals based on these estimates.

RESULTS

Within-participant analysis showed that on school days (vs. nonschool days), children (1) slept less (β = -0.17, 95% CI = -0.21, -0.13), (2) were less sedentary (β = -0.05, 95% CI = -0.09, -0.02), and (3) had comparable moderate-to-vigorous physical activity (MVPA; β = -0.05, 95% CI = -0.11, 0.00). Between-participant analysis showed that, on school days, children with higher sleep carryover experienced greater decreases in sleep (β = 0.44, 95% CI = 0.08, 0.71), children with higher body mass index z-score decreased sedentary behavior more (β = -0.41, 95% CI = -0.64, -0.13), and children with lower MVPA increased MVPA more (β = -0.41, 95% CI -0.64, -0.13). Cluster analysis demonstrated four distinct patterns of connections between time-use activity behaviors and school (High Activity, Sleep Resilient, High Sedentary, and Dysregulated Sleep).

CONCLUSIONS

Using a combination of person-centered and more traditional variable-centered approaches, we identified patterns of interrelated behaviors that differed on school, and nonschool days. Findings can inform targeted intervention strategies tailored to children's specific behavior patterns.

Beyond sleep duration: Sleep timing as a risk factor for childhood obesity

BACKGROUND

Ample evidence attests to the relationship between short sleep duration, sleep problems and childhood obesity. However, few studies have examined the association between sleep timing and obesity in children.

OBJECTIVES

To investigate how sleep duration, problems and timing relate to obesity and obesogenic behaviours in children.

METHODS

Eighty-five children (58.8% girls) with severe obesity and mean (SD) age of 12.1 (2.9) years, were matched by age and sex with peers with normal weight (n = 85,12.0 [2.8] years). Sleep and moderate-to-vigorous physical activity (MVPA) were measured via accelerometer for seven consecutive days. Children self-reported emotional eating on the Dutch eating behavior questionnaire. Parents reported children's screen time and sleep problems.

RESULTS

Children with severe obesity had significantly later mean mid-sleep time, overall (36 minutes later, P < .001), on school nights (36 minutes later, P < .001) and weekend nights (39 minutes later, P = .002) compared to children with normal weight. Children with obesity had more sleep problems (P = .030), but no differences emerged in sleep duration or social jetlag. After adjusting for demographic factors, mid-sleep time was positively related to screen time (P = .030). Mid-sleep time and sleep duration were inversely related to time in MVPA (Ps ≤ .041). There were no other significant associations between the sleep variables and the obesogenic behaviours.

CONCLUSIONS

Later sleep timing was related to obesogenic behaviours in children and may represent an obesity risk factor.

The impact of summer vacation on children's obesogenic behaviors and body mass index: a natural experiment

BACKGROUND

Children's BMI gain accelerates during summer. The Structured Days Hypothesis posits that the lack of the school day during summer vacation negatively impacts children's obesogenic behaviors (i.e., physical activity, screen time, diet, sleep). This natural experiment examined the impact of summer vacation on children's obesogenic behaviors and body mass index (BMI).

METHODS

Elementary-aged children (n = 285, 5-12 years, 48.7% male, 57.4% African American) attending a year-round (n = 97) and two match-paired traditional schools (n = 188) in the United States participated in this study. Rather than taking a long break from school during the summer like traditional schools, year-round schools take shorter and more frequent breaks from school. This difference in school calendars allowed for obesogenic behaviors to be collected during three conditions: Condition 1) all children attend school, Condition 2) year-round children attend school while traditional children were on summer vacation, and Condition 3) summer vacation for all children. Changes in BMI z-score were collected for the corresponding school years and summers. Multi-level mixed effects regressions estimated obesogenic behaviors and monthly zBMI changes. It was hypothesized that children would experience unhealthy changes in obesogenic behaviors when entering summer vacation because the absence of the school day (i.e., Condition 1 vs. 2 for traditional school children and 2 vs. 3 for year-round school children).

RESULTS

From Condition 1 to 2 traditional school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 24.2, 95CI = 10.2, 38.2), screen time minutes (∆ = 33.7, 95CI = 17.2, 50.3), sleep midpoint time (∆ = 73:43, 95CI = 65:33, 81:53), and sleep efficiency percentage (-∆ = 0.7, 95CI = -1.1, - 0.3) when compared to year-round school children. Alternatively, from Condition 2 to 3 year-round school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 54.5, 95CI = 38.0, 70.9), light physical activity minutes (∆ = - 42.2, 95CI = -56.2, - 28.3) MVPA minutes (∆ = - 11.4, 95CI = -3.7, - 19.1), screen time minutes (∆ = 46.5, 95CI = 30.0, 63.0), and sleep midpoint time (∆ = 95:54, 95CI = 85:26, 106:22) when compared to traditional school children. Monthly zBMI gain accelerated during summer for traditional (∆ = 0.033 95CI = 0.019, 0.047) but not year-round school children (∆ = 0.004, 95CI = -0.014, 0.023).

CONCLUSIONS

This study suggests that the lack of the school day during summer vacation negatively impacts sedentary behaviors, sleep timing, and screen time. Changes in sedentary behaviors, screen time, and sleep midpoint may contribute to accelerated summer BMI gain. Providing structured programming during summer vacation may positively impact these behaviors, and in turn, mitigate accelerated summer BMI gain.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03397940 . Registered January 12th 2018.

Sleep timing and sleep problems of preschoolers in Aotearoa/New Zealand: relationships with ethnicity and socioeconomic position

OBJECTIVES

To provide descriptive sleep data and explore sleep inequities, we investigated maternal reports of when and how well Māori (Indigenous) and non-Māori preschoolers sleep, and examined relationships between ethnicity (child and maternal), socioeconomic position (SEP) and sleep timing and problems of 3-4 year old children in Aotearoa/New Zealand (NZ).

METHODS

This study involved cross-sectional analysis of data from the Moe Kura: Mother and Child, Sleep and Wellbeing in Aotearoa/New Zealand longitudinal study. Log-binomial regression models were used to investigate associations between child and maternal demographic variables and preschooler bedtimes, social jetlag and maternally-reported sleep problems. Child models included child ethnicity, child gender, area- and individual-level deprivation. Maternal models included maternal ethnicity, maternal age, area- and individual-level deprivation.

RESULTS

340 Māori and 570 non-Māori preschoolers and their mothers participated. Māori preschoolers had later average bedtimes and wake times than non-Māori preschoolers. Ethnicity and area-level deprivation were independently associated with later bedtimes. Ethnicity was associated with social jetlag and sleep problems, independent of SEP. Individual-level deprivation was associated with problems falling asleep. Preschoolers of Māori mothers in least deprived areas were more likely to have problems falling asleep than preschoolers of non-Māori mothers in least deprived areas.

CONCLUSIONS

Research is needed to understand what sleep timing differences mean for preschoolers' wellbeing in NZ. Fundamental causes of social and economic disadvantage experienced by Indigenous children and mothers and by families who hold low SEP must be addressed, in order to eliminate sleep health inequities in early childhood.

Associations between paediatric fatigue and eating behaviours

BACKGROUND

In adults, poor sleep quality is associated with increased obesogenic eating behaviours; less is known about this relationship in youth. The objectives of this study were to assess the strength of association between fatigue-related quality of life (QoL) and eating behaviours among youth and to describe the associations in participants with percent body fat (%BF) above and below the 90th percentile for sex and age.

METHODS

Caregiver-reported measures of fatigue (Pediatric QoL Multidimensional Fatigue Scale) and eating behaviours (Child Eating Behaviour Questionnaire) were obtained from participants aged 8-17 years. %BF was measured by iDXA and grouped by sex- and age-specific percentiles. Multiple linear regression adjusting for age, sex and race/ethnicity was used.

RESULTS

Of the 352 participants (49% male), 44.6% had %BF >90th percentile. General, sleep/rest and cognitive fatigue QoL was inversely associated with food approach behaviours: food responsiveness, enjoyment of food, emotional overeating and desire to drink. For participants with %BF >90th percentile, higher general fatigue QoL was associated with higher satiety responsiveness (0.13; 95% confidence interval [CI 0.03, 0.24]). For participants with %BF ≤90th percentile, higher general fatigue QoL was associated with less satiety responsiveness (-0.16; 95% CI [-0.31, -0.01]).

CONCLUSION

Less fatigue symptoms were associated with less behaviours associated with food approach among paediatric participants. For participants with %BF >90th percentile, less symptoms of general fatigues corresponded with more satiety. Though causation has yet to be established, youth with elevated %BF should be screened for fatigue symptoms and offered counselling on sleep hygiene or a sleep medicine referral to help mitigate weight gain.

Behavioral and social routines and biological rhythms in prevention and treatment of pediatric obesity

A growing body of research supports the potential importance of behavioral and social routines for children's health promotion and obesity risk reduction. Evidence in support of this comes from multiple lines of research, which suggest that specific behavioral routines, namely, eating and sleep routines, may be protective against excessive weight gain and development of pediatric obesity. Emerging work also supports the potential importance of the timing of these behavioral routines. From a circadian perspective, alignment of behavioral and social routines with underlying circadian rhythms may be particularly important for enhancing children's weight regulation. Specifically, engaging in appropriately timed behavioral routines may serve to entrain circadian rhythms that affect metabolism and weight regulation. Thus, in addition to promoting healthier eating, activity, and sleep behaviors for prevention and treatment of pediatric obesity, it may also be important to consider promotion of consistency in, and optimal timing of, these behaviors in an effort to enhance extant prevention and treatment approaches. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Resetting the Aging Clock: Implications for Managing Age-Related Diseases

Worldwide, individuals are living longer due to medical and scientific advances, increased availability of medical care and changes in public health policies. Consequently, increasing attention has been focused on managing chronic conditions and age-related diseases to ensure healthy aging. The endogenous circadian system regulates molecular, physiological and behavioral rhythms orchestrating functional coordination and processes across tissues and organs. Circadian disruption or desynchronization of circadian oscillators increases disease risk and appears to accelerate aging. Reciprocally, aging weakens circadian function aggravating age-related diseases and pathologies. In this review, we summarize the molecular composition and structural organization of the circadian system in mammals and humans, and evaluate the technological and societal factors contributing to the increasing incidence of circadian disorders. Furthermore, we discuss the adverse effects of circadian dysfunction on aging and longevity and the bidirectional interactions through which aging affects circadian function using examples from mammalian research models and humans. Additionally, we review promising methods for managing healthy aging through behavioral and pharmacological reinforcement of the circadian system. Understanding age-related changes in the circadian clock and minimizing circadian dysfunction may be crucial components to promote healthy aging.

Chronotype, Social Jet Lag, and Cardiometabolic Risk Factors in Early Adolescence

IMPORTANCE

Inadequate sleep duration and quality increase the risk of obesity. Sleep timing, while less studied, is important in adolescents because increasing evening preferences (chronotypes), early school start times, and irregular sleep schedules may cause circadian misalignment.

OBJECTIVE

To investigate associations of chronotype and social jet lag with adiposity and cardiometabolic risk in young adolescents.

DESIGN, SETTING, AND PARTICIPANTS

Starting in 1999, Project Viva recruited pregnant women from eastern Massachusetts. Mother-child in-person visits occurred throughout childhood. From January 23, 2012, to October 16, 2016, 804 adolescents aged 12 to 17 years completed 5 days or more of wrist actigraphy, questionnaires, and anthropometric measurements. A cross-sectional analysis using these data was conducted from April 31, 2018, to May 1, 2019.

EXPOSURES

Chronotype, measured via a continuous scale with higher scores indicating greater evening preferences, and social jet lag, measured as the continuous difference in actigraphy sleep midpoint in hours from midnight on weekends vs weekdays, with higher values representing more delayed sleep timing on weekends.

MAIN OUTCOMES AND MEASURES

Adiposity, measured via anthropometry and dual-energy x-ray absorptiometry. For a subset of 479 adolescents with blood samples, cardiometabolic risk scores were computed as the mean of 5 sex- and cohort-specific z scores for waist circumference, systolic blood pressure, inversely scaled high-density lipoprotein cholesterol, and log-transformed triglycerides and homeostatic model of insulin resistance.

RESULTS

Among the 804 adolescents in the study, 418 were girls and 386 were boys, with a mean (SD) age of 13.2 (0.9) years. In multivariable models adjusted for age, puberty, season, and sociodemographics, associations of chronotype and social jet lag with adiposity varied by sex. For girls, greater evening preference was associated with a 0.58-cm (95% CI, 0.12-1.03 cm; P = .04 for interaction) higher waist circumference and 0.16 kg/m2 (95% CI, 0.01-0.31 kg/m2; P = .03 for interaction) higher fat mass index as measured by dual-energy x-ray absorptiometry; each hour of social jet lag was associated with a 1.19-cm (95% CI, 0.04-2.35 cm; P = .21 for interaction) higher waist circumference and 0.45 kg/m2 (95% CI, 0.09-0.82 kg/m2; P = .01 for interaction) higher fat mass index as measured by dual-energy x-ray absorptiometry. Associations of social jet lag and evening chronotypes persisted for many measures of adiposity after adjustment for sleep duration and other lifestyle behaviors. By contrast, no associations were observed in boys. There were no associations with the cardiometabolic risk score for either sex, although statistical power was low for this outcome.

CONCLUSIONS AND RELEVANCE

Evening chronotypes and social jet lag were associated with greater adiposity in adolescent girls but not adolescent boys. Interventions aimed at improving sleep schedules may be useful for obesity prevention, especially in girls.

Potential circadian and circannual rhythm contributions to the obesity epidemic in elementary school age children

Children gain weight at an accelerated rate during summer, contributing to increases in the prevalence of overweight and obesity in elementary-school children (i.e., approximately 5 to 11 years old in the US). Int J Behav Nutr Phys Act 14:100, 2017 explained these changes with the "Structured Days Hypothesis" suggesting that environmental changes in structure between the school year and the summer months result in behavioral changes that ultimately lead to accelerated weight gain. The present article explores an alternative explanation, the circadian clock, including the effects of circannual changes and social demands (i.e., social timing resulting from societal demands such as school or work schedules), and implications for seasonal patterns of weight gain. We provide a model for understanding the role circadian and circannual rhythms may play in the development of child obesity, a framework for examining the intersection of behavioral and biological causes of obesity, and encouragement for future research into bio-behavioral causes of obesity in children.

Association between social jetlag food consumption and meal times in patients with obesity-related chronic diseases

Chronic disruption of the synchronous relationship between endogenous and exogenous circadian timing is associated with the development of obesity and metabolic disease. Social jetlag is a measure of circadian misalignment and has been identified as a risk factor for overweight and related diseases. However, the mechanisms involved in this relationship remain underexplored. The objective of this study was to investigate the association between social jetlag and food consumption at late meal timing in patients with obesity-related chronic diseases. This study included 792 individuals (73% female; age 55.9 ± 12.4 years) in which the prevalence of social jetlag (>1h) was 24.4% (n = 194). Participants with social jetlag reported late meal timing for breakfast, early afternoon snack and dinner. Individuals with social jetlag also reported a higher intake of total calories (kcal), protein, total fat, saturated fat, cholesterol, and servings of meat and eggs and sweets in relation to those without social jetlag. Regarding the consumption during each meal of the day, participants with social jetlag had consumed more calories, saturated fat and cholesterol during dinner; more protein, total fat, saturated fat, and cholesterol during lunch; and more total fat and saturated fat during morning snack. In addition, individuals with social jetlag had a higher risk of inadequate consumption of total fat, saturated fat and cholesterol intake when compared with those without social jetlag. We conclude that social jetlag is associated with a poor diet and later meal times, which should be avoided in individuals with obesity-related chronic diseases. More studies are needed to confirm these findings.

Sleep duration and quality are associated with eating behavior in low-income toddlers

OBJECTIVE

The present study examined whether different sleep health parameters (duration, timing, and quality) are associated with obesity-related eating behaviors including emotional overeating, food responsiveness, enjoyment of food, satiety responsiveness, and eating in the absence of hunger (EAH), during toddlerhood.

DESIGN

Among 134 low-income 33-month-old children, parents reported on child sleep parameters, including sleep quality (Children's Sleep Wake Scale; CSWS) and usual bedtimes and wake times on weekdays and weekends (weeknight sleep duration, weekday-to-weekend bedtime delay). Child eating behaviors were assessed using both observed and parent-report measures. Child Emotional Overeating, Food Responsiveness, Enjoyment of Food, and Satiety Responsiveness were measured by parent report using the Child Eating Behavior Questionnaire-Toddler. Observed child EAH was evaluated by measuring kilocalories of palatable foods consumed following a meal. Multivariable linear regression was used to examine the associations between sleep parameters and eating behaviors.

RESULTS

Poorer child sleep quality was associated with greater Emotional Overeating (standardized β = -0.20 (SE 0.09), p < .05) and greater Food Responsiveness (β = -0.18 (SE 0.09), p < .05). Shorter child nighttime sleep duration was associated with greater EAH kcal consumed (standardized β = -0.22 (SE 0.09), p < .05). Child bedtime delay was not associated with any of the eating behaviors, and no child sleep variables were associated with either Enjoyment of Food or Satiety Responsiveness.

CONCLUSIONS

Shorter nocturnal sleep duration and poorer sleep quality during toddlerhood were associated with some, but not all, of the obesity-related eating behaviors. Poor sleep health may promote childhood obesity risk through different eating behavior pathways. As children growing up in poverty may experience greater sleep decrements, sleep duration and sleep quality may be important targets for intervention among low-income families with young children.

Changes in children's sleep and physical activity during a 1-week versus a 3-week break from school: a natural experiment

Study Objectives

To examine changes in elementary aged children's sleep and physical activity during a 1-week and a 3-week school break.

Methods

Sleep and physical activity of elementary children (n = 154, age = 5-9 years, 44.8% female, 65.5% African American) were collected over 7 weeks that included a 1-week break in two schools and a 3-week break in a single school. Mixed regression models estimated sleep and physical activity changes within and between groups (i.e. 1-week vs. 3-weeks) during school and school break weeks.

Results

Compared to school weeks, bed times shifted 72.7 (95% CI = 57.5, 87.9) and 75.4 (95% CI = 58.1, 92.7) minutes later on weekdays during the 1-week and 3-week break, respectively. Wake times shifted 111.6 (95% CI = 94.3, 128.9) and 99.8 (95% CI = 80.5, 119.1) minutes later on weekdays during 1-week and 3-week breaks. On weekdays during the 3-week break, children engaged in 33.1 (95% CI = 14.1, 52.2) more sedentary minutes and -12.2 (-20.2, -4.2) fewer moderate-to-vigorous physical activity minutes/day. No statistically significant changes in children's sedentary, light, or moderate-to-vigorous physical activity (MVPA) minutes were observed on weekdays during the 1-week break. Between-group differences in the change in time sedentary (32.1-95% CI = 5.8, 58.4), and moderate-to-vigorous (-13.0-95% CI = -23.9, -2.0) physical activity were observed.

Conclusions

Children's sleep shifted later on both 1-week and 3-week breaks. Children's activity changed minimally on weekdays during a 1-week school break and more during a 3-week school break. Displaced sleep and reductions in activity are intervention targets for mitigating unhealthy weight gain during extended breaks from school.

Prospective Associations between Weekend Catch-Up Sleep, Physical Activity, and Childhood Obesity

BACKGROUND

Catch-up sleep and low physical activity on weekends have been commonly documented. Preliminary evidence on Chinese children, however, has shown a variety of weekly physical activity patterns. This study examined the prospective associations between weekend catch-up patterns of sleep and physical activity and obesity over a 2-year period in Chinese children.

METHODS

Prospective data from 599 children in the Understand Children's Activity and Nutrition (UCAN) cohort study were analyzed. Weekly patterns of obesogenic behaviors (physical activity and sleep duration) were assessed annually over a 2-year period. Moderate-to-vigorous physical activity (MVPA) and sedentary time were determined by ActiGraph accelerometry. Data on sleep durations and sociodemographic factors were obtained from parental-reported questionnaires. Weekend catch-up sleep and MVPA patterns were calculated and examined in relation to childhood obesity after controlling for sociodemographic variables and sedentary time.

RESULTS

Every additional hour of average weekly sleep duration was associated with a 16% decrease in the odds of obesity (OR: 0.841, 95%CI: 0.709 - 0.999). After adjustment of average sleep duration, weekend sleep catch-up categories showed no association with obesity risk. Over a 2-year period, half of the children demonstrated weekend catch-up MVPA. Weekend catch-up MVPA for less than 20 minutes (OR: 0.473, 95%CI: 0.258 - 0.867) or more than 20 minutes (OR: 0.505, 95%CI: 0.257 - 0.993) were both related to lower risk of obesity.

CONCLUSIONS

Weekend catch-up sleep did not ameliorate the risk of childhood obesity, whereas weekend catch-up MVPA did reduce that risk. More research is needed to explore the factors contributing to these obesogenic behavior patterns.

Pilot data on the association between social jetlag and obesity-related characteristics in Dutch adolescents over one year

OBJECTIVE

Social jetlag, a form of chronic circadian misalignment, has previously been associated with obesity in adults. We aimed to investigate the association between social jetlag and obesity-related characteristics in Dutch adolescents over a 1-year period.

METHODS

We analysed data of 83 adolescents, who were recruited from a Dutch cohort born between the years 1990 and 1993. At the age of 16 and 17y, we determined anthropometric measurements, body composition, physical activity, hours of television use, and self-reported sleep duration. Using linear regression models, we assessed the association between social jetlag, defined as more than a 1-hour difference between the midpoint of sleep during weekdays and weekend days, and body mass index (BMI), body fat percentage, and waist circumference at baseline and after one year. We corrected the analysis for sex, sleep, physical activity, and hours of television use.

RESULTS

At age 16y, we observed that social jetlag was highly prevalent, with only 13% of the adolescents reporting no social jetlag (≤1 h), whereas 29% and 58% reported a social jetlag of >1-2 h and ≥2 h. In a cross-sectional analysis, we observed at age 16y a significant higher BMI in the group with no social jetlag, compared to the group with >1- to 2-hour and ≥2-hour social jetlag after adjustment for sex (-0.81 kg/m², 95% confidence interval = -3.1 to 1.4; and -2.09 kg/m², 95% confidence interval = -4.1 to -0.1). This association remained significant after correction for the other possible confounders. No significant associations were observed between social jetlag at age 16y and changes in obesity-related characteristics over one year.

CONCLUSION

Our pilot data showed that social jetlag is highly prevalent in adolescents, with social jetlag associated with a lower BMI; however, in this small group, social jetlag was not associated with changes in obesity-related characteristics over time.