Sleep: population epidemiology and concordance in Australian children aged 11-12 years and their parents

Day-to-day bidirectional associations between sleep and emotion states in early childhood: Importance of end-of-day mood for sleep quality

OBJECTIVES

Poor quality sleep can impact emotions and emotion regulation, resulting in a "sleep-mood" cycle where poor sleep affects mood and vice-versa. This relationship is poorly understood during early childhood, when sleep patterns and emotion displays are rapidly changing. This study aimed to understand the day-to-day effects of poor sleep on emotions in preschoolers by using objective (actigraphy) and subjective (ecological momentary assessment) measures to assess both between- and within-child effects. We hypothesized that disrupted sleep would lead to affect disruptions and vice versa.

METHODS

This study included 133 preschoolers and their caregivers recruited from the community. Children's sleep was measured via actigraphy (ActiGraph GT3X+) across 1week. Affect was collected concurrently via caregiver report during an ecological momentary assessment protocol. Caregivers reported on their child's affect four times per day: morning, afternoon, early evening, and before bed.

RESULTS

Multilevel modeling analyses revealed that children with sleep disturbances displayed less positive affect overall, more negative affect in the evenings, and alterations in positive affect lability, and that daytime affect was associated with subsequent nighttime sleep. Within-child associations also showed fluctuations in positive affect correlated with shorter sleep durations and later bedtimes.

CONCLUSIONS

This study identified both between- and within-child associations between sleep and affect in early childhood, revealing a dynamic and reciprocal relationship between the two. These findings highlight the importance of considering both sleep and affect in early childhood interventions, as promoting positive affect may enhance sleep quality and vice versa.

Passing on the Zzz's: Adolescent sleep attitudes are associated with sleep behaviors and parental prioritization of sleep

OBJECTIVES

The purpose of this study is to examine adolescent attitudes about the importance of sleep and how they relate to adolescent sleep behaviors and parent sleep attitudes.

METHODS

Participants included families with adolescents aged 10-17years and a parent (N = 170 dyads) who completed a virtual assessment. Adolescents reported on their sleep impairment and sleep hygiene behaviors, and all participants completed a newly developed scale to assess attitudes toward the importance of prioritizing sleep over other activities/responsibilities.

RESULTS

Results suggest that older adolescents reported more negative sleep attitudes, and adolescents reported more negative sleep attitudes compared to adult/parent participants. More negative sleep attitudes were associated with poorer sleep hygiene behaviors. Parent sleep attitudes significantly predicted their adolescent's sleep attitudes, even after adjusting for family income, education, and adolescent age and sex.

CONCLUSIONS

This is the first study to our knowledge to quantitatively examine adolescent sleep attitudes. Findings suggest that sleep attitudes are important for adolescent sleep, and may develop within the family system via parental socialization. Future research and implications for intervention are discussed.

Time use and dimensions of healthy sleep: A cross-sectional study of Australian children and adults

BACKGROUND

Sleep is increasingly recognized as a multidimensional construct that occurs within the 24-hour day. Despite advances in our understanding, studies continue to consider the relationship between sleep, sedentary time and physical activity separately, and not as part of the 24-hour day.

AIMS

To determine the association between the 24-hour activity composition and dimensions of healthy sleep.

METHODS

This study examined data on 1168 children (mean age 12years; 49% female) and 1360 adults (mean age 44years; 87% female) collected as part of the Child Health CheckPoint study. Participants were asked to wear a GENEActiv monitor (Activinsights, Cambs, UK) on their nondominant wrist for eight consecutive days to measure 24-hour time-use. Compositional data analysis was used to examine the association between time use (actigraphy-derived sleep duration, sedentary time, light physical activity and moderate-vigorous physical activity) and dimensions of healthy sleep. Healthy sleep was conceptualized in terms of continuity/efficiency, timing, alertness/sleepiness, satisfaction/quality, and regularity. Time allocations were also examined.

RESULTS

The 24-hour activity composition was significantly associated with all objectively measured and self-report dimensions of healthy sleep in both children and adults. Allocating more time to sleep was associated with earlier sleep onsets, later sleep offsets, less efficient and more consistent sleep patterns for both children and adults.

CONCLUSION

This study highlights the integral relationship between daily activities and dimensions of sleep. Considering sleep within the 24-hour day activity composition framework may help inform lifestyle decisions to improve sleep health.

Polygenic Risk Scores and the Risk of Childhood Overweight/Obesity in Association With the Consumption of Sweetened Beverages: A Population-Based Cohort Study

Background: Sugar-sweetened beverage (SSB) and non-nutritive sweetened beverage (NNSB) consumption is associated with obesity and are targets for population-level dietary interventions. In children (<16 years), we evaluate whether SSB or NNSB consumption is associated with subsequent (2 years later) overweight and/or obesity, and the effect of consumption on subsequent overweight/obesity differs by BMI polygenic risk score (BMI-PRS). Methods: The nationally representative Longitudinal-Study-of-Australian-Children had biennial data collection from birth (n = 5107) until age 14/15 years (n = 3127). At age 11/12 years, a comprehensive biomedical assessment, including PRS assessment, was undertaken (n = 1422). Parent- or self-reported beverage consumption (SSBs: soft drinks, energy drinks, and/or juice; NNSBs: diet drinks) was measured as any/none over previous 24 hours. BMI-PRS was derived using published results (high PRS ≥75th percentile). At ages 4/5-14/15 children were classified as having obesity, overweight/obesity, or not having overweight/obesity using BMI z-score (CDC cut points). Results: SSB consumption had limited association with subsequent overweight/obesity. NNSB consumption was associated with ∼8% more children with subsequent overweight/obesity at most ages. In older children with high BMI-PRS, associations between NNSB consumption and subsequent overweight/obesity strengthened with age [at age 14-15 for high BMI-PRS, difference in proportion with overweight/obesity among NNSB consumers vs. nonconsumers = 0.38 (95% confidence interval: 0.22 to 0.55, p ≤ 0.001)]. There was limited association between SSB consumption and BMI-PRS. Conclusion: NNSB consumption was associated with increased risk of overweight/obesity for children with greater genetic risk at older ages (12-15 years). Focused intervention among children with high genetic risk could target NNSB consumption; however, reverse causality (children with genetic risk and/or high BMI consume more NNSBs) cannot be excluded.

Branched-chain amino acids and sleep: a population-derived study of Australian children aged 11-12 years and their parents

Micronutrients, particularly amino acids, are thought to play an important role in sleep regulation and maintenance. While tryptophan is a known predictor of sleep, less is known about branched-chain amino acids (BCAAs), which compete with tryptophan for transport across the blood-brain barrier. The aim of this study was to determine the association between BCAAs and actigraphy-derived sleep duration, timing and efficiency, and self-reported trouble sleeping. This study examined data on children and adults collected as part of the Child Health CheckPoint study. Linear mixed models, adjusted for geographic clustering, were used to determine the association between BCAAs and sleep characteristics. Complete-case analysis was conducted for 741 children aged 11-12 years old (51% females) and 941parents (87% mothers). While BCAAs were significantly associated with children's sleep duration, timing and self-reported trouble sleeping, no associations were observed in adults, in fully adjusted models. In children, higher levels of BCAAs are associated with shorter sleep duration, delayed sleep timing, and more frequent reports of trouble sleeping.

The impact of weather on time allocation to physical activity and sleep of child-parent dyads

PURPOSE

Previous studies showed that unfavourable weather conditions discourage physical activity. However, it remains unclear whether unfavourable weather conditions have a differential impact on physical activity in children compared with adults. We aim to explore the differential impact of weather on time allocation to physical activity and sleep by children and their parents.

METHOD

We use nationally representative data with time use indicators objectively measured on multiple occasions for >1100 Australian pairs of 12-13-year-old children and their middle-aged parents, coupled with daily meteorological data. We employ an individual fixed effects regression model to estimate the causal impact of weather.

RESULTS

We find that unfavourable weather conditions, as measured by cold or hot temperatures or rain, cause children to reduce moderate- and vigorous-intensity physical activity time and increase sedentary time. However, such weather conditions have little impact on children's sleep time or the time allocation of their parents. We also find substantial differential weather impact, especially on children's time allocation, by weekdays/weekends and parental employment status, suggesting that these factors may contribute to explaining the differential weather impact that we observed. Our results additionally provide evidence of adaptation, as temperature appears to have a more pronounced impact on time allocation in colder months and colder regions.

CONCLUSION

Our finding of a negative impact of unfavourable weather conditions on the time allocated to physical activity by children indicates a need to design policies to encourage them to be more physically active on days with unfavourable weather conditions and hence improve child health and wellbeing. Evidence of a more pronounced and negative impact on the time allocated to physical activity by children than their parents suggests that extreme weather conditions, including those associated with climate change, could make children vulnerable to reduced physical activity.

Multidimensional Sleep and Cardiometabolic Risk Factors for Type 2 Diabetes: Examining Self-Report and Objective Dimensions of Sleep

Purpose:

The purpose of the study was to determine the association between objective and self-report measures of sleep and cardiometabolic risk factors for type 2 diabetes.

Methods:

This study examines data on Australian adults, collected as part of the Child Health CheckPoint study. Sleep was examined in terms of actigraphy-derived sleep duration, timing, efficiency and variability; and self-report trouble sleeping. Cardiometabolic risk factors for type 2 diabetes were examined in terms of body mass index and biomarkers of inflammation and dyslipidemia. Generalized estimating equations, adjusted for geographic clustering, were used to determine the association between measures of sleep and cardiometabolic risk factors.

Results:

Complete case analysis was conducted for 1017 parents (87% mothers). Both objective and self-report measures of sleep were significantly but weakly associated with cardiometabolic risk factors.

Conclusion:

Both objective and self-report measures of sleep are significantly associated with cardiometabolic risk factors for type 2 diabetes. Self-report troubled sleep is associated with poorer cardiometabolic health, independent of actigraphy-derived sleep parameters.

The physical home environment and sleep: What matters most for sleep in early childhood

The physical home environment is thought to play a crucial role in facilitating healthy sleep in young children. However, relatively little is known about how various features of the physical home environment are associated with sleep in early childhood, and some of the recommendations clinicians make for improving child sleep environments are based on limited research evidence. The present study examined how observer and parent descriptions of the child's physical home environment were associated with child sleep, measured using actigraphy and parent's reports, across a year in early childhood. The study used a machine learning approach (elastic net regression) to specify which aspects of the physical home environment were most important for predicting five aspects of child sleep, sleep duration, sleep variability, sleep timing, sleep activity, and latency to fall asleep. The study included 546 toddlers (265 females) recruited at 30 months of age and reassessed at 36 and 42 months of age. Poorer quality physical home environments were associated with later sleep schedules, more variable sleep schedules, shorter sleep durations, and more parent-reported sleep problems in young children. The most important environmental predictors of sleep were room sharing with an adult, bed sharing, and quality of both the child's sleep space and the wider home environment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Family Social Support and Weight-Related Behaviors of School-Age Children: An Exploratory Analysis

Families are a key provider of support that may encourage positive weight-related behaviors. Yet little is known about the relation of family support to children’s performance of weight-related behaviors. Mothers (N = 524) who completed an online survey were categorized as having low, moderate, or high family support for fruit/vegetable intake, breakfast intake, limiting sugar-sweetened beverage intake, physical activity, limiting sedentary screentime, and sleep. ANOVA revealed that children in families with high support for breakfast ate this meal significantly more often. Additionally, children in families with low support for limiting sugar-sweetened beverages had significantly greater intake. Surprisingly, families with moderate support for physical activity and sleep tended to have children with lower physical activity level, sleep duration, and sleep quality, and fewer days/week with set bedtimes than those with low and high support. Binomial logistic regression revealed that high family support for eating breakfast, limiting sugar-sweetened beverages, and getting sufficient sleep had greater odds of meeting recommendations for these behaviors. Findings suggest that greater family support for healthy weight-related behaviors tends to be associated with children’s performance of these behaviors. Future interventions should further examine the impact of different types of family support on weight-related behaviors to better understand this complex interplay.

Sleep and cardiometabolic risk: a cluster analysis of actigraphy-derived sleep profiles in adults and children

STUDY OBJECTIVES

Sleep plays an important role in cardiometabolic health. Although the importance of considering sleep as a multidimensional construct is widely appreciated, studies have largely focused on individual sleep characteristics. The association between actigraphy-derived sleep profiles and cardiometabolic health in healthy adults and children has not been examined.

METHODS

This study used actigraphy-measured sleep data collected between February 2015 and March 2016 in the Child Health CheckPoint study. Participants wore actigraphy monitors (GENEActiv Original, Cambs, UK) on their nondominant wrist for 7 days and sleep characteristics (period, efficiency, timing, and variability) were derived from raw actigraphy data. Actigraphy-derived sleep profiles of 1,043 Australian children aged 11-12 years and 1,337 adults were determined using K-means cluster analysis. The association between cluster membership and biomarkers of cardiometabolic health (blood pressure, body mass index, apolipoproteins, glycoprotein acetyls, composite metabolic syndrome severity score) were assessed using Generalized Estimating Equations, adjusting for geographic clustering, with sex, socioeconomic status, maturity stage (age for adults, pubertal status for children), and season of data collection as covariates.

RESULTS

Four actigraphy-derived sleep profiles were identified in both children and adults: short sleepers, late to bed, long sleepers, and overall good sleepers. The overall good sleeper pattern (characterized by adequate sleep period time, high efficiency, early bedtime, and low day-to-day variability) was associated with better cardiometabolic health in the majority of comparisons (80%).

CONCLUSION

Actigraphy-derived sleep profiles are associated with cardiometabolic health in adults and children. The overall good sleeper pattern is associated with more favorable cardiometabolic health.

Do Mothers Have Worse Sleep Than Fathers? Sleep Imbalance, Parental Stress, and Relationship Satisfaction in Working Parents

PURPOSE

Previous research indicates that mothers take a larger responsibility for child care during the night and that they have more disturbed sleep than fathers. The purpose of this study was to determine whether such a sleep imbalance exists in working parents of young children, and the extent to which it depends on the way sleep is measured. The study also examined whether imbalanced sleep between parents predicts parental stress and relationship satisfaction.

METHODS

Sleep was measured for seven consecutive days in 60 parenting couples (average age of the youngest child: 3.3 years ± SD 2.5 years). Actigraphs were worn across the week, and ratings of sleep, parental stress, and relationship satisfaction were made daily.

RESULTS

Mothers perceived their sleep quality as worse (b= -0.38 scale units, p<0.001), with more wake periods (b= +0.96 awakenings, p<0.001) but with longer sleep duration (b= +32.4 min, p<0.01) than fathers. Actigraphy data confirmed that mothers slept longer than fathers (b= +28.03 min, p<0.001), but no significant differences were found for wake time, number of awakenings or who woke up first during shared awakenings. Furthermore, there was no difference in whether mothers and fathers slept sufficiently. The level of sleep imbalance between parents did not predict parental stress. A larger imbalance in subjective sleep sufficiency predicted decreased relationship satisfaction for fathers (b= -0.13 scale units, p<0.01) but increased relationship satisfaction for mothers (b= 0.14 scale units, p<0.05). No other sleep imbalance measures predicted relationship satisfaction.

CONCLUSION

Our findings are in line with previous research on sleep in men and women in general, with longer sleep and subjective reports of sleep disturbances in women, rather than previous research on sleep in parents of young children. Thus, we found no evidence of a sleep imbalance when both parents have similar working responsibilities.

Sleep and cardiometabolic health in children and adults: examining sleep as a component of the 24-h day

STUDY OBJECTIVES

Sleep, physical activity and sedentary time are all known to play a role in cardiometabolic health. Compositional data analysis (CoDA) enables us to examine associations between 24-h use of time and health outcomes.

METHODS

Data were collected in the Child Health CheckPoint study, a one-off national population-cohort study conducted between February 2015 and March 2016. Wrist-worn actigraphy monitors (GENEActiv Original, Cambs, UK) were used to measure activity behaviours (sleep, physical activity and sedentary time) and sleep characteristics (sleep variability, midsleep, efficiency). CoDA was applied to determine the association between 24-h use of time and cardiometabolic risk markers (blood pressure; body mass index; apolipoprotein B/A1; glycoprotein acetyls; and composite metabolic syndrome score). Substitution modelling (one-for-remaining and one-for-one) examined the associations of reallocating sleep time with other activity behaviours.

RESULTS

Data were available for 1073 Australian children aged 11-12 years (50% male) and 1337 adults (13% male). Strong association was found between 24-h use of time and all cardiometabolic health outcomes. Longer sleep was associated with more favourable cardiovascular health. Sleep characteristics other than duration (efficiency, timing, variability) were weakly and inconsistently associated with outcomes. Reallocating time from sleep to moderate-vigorous physical activity (MVPA) had favourable associations with cardiometabolic health, but reallocating from sleep to sedentary time was associated with less favourable cardiometabolic health.

CONCLUSION

The 24-h activity composition is strongly associated with cardiometabolic health in children and adults. Days with more sleep and MVPA are associated with improved cardiometabolic health.

Modifiable parental factors in adolescent sleep: A systematic review and meta-analysis

Sleep problems are prevalent during adolescence, but parents may be able to support adolescents to sleep better. A systematic search of records from six databases from inception up to November 2019, identified 103 peer-reviewed publications that examined behaviourally and cognitively modifiable parental factors associated with sleep in adolescents aged 12-18 years. Although included studies were largely cross-sectional and heterogeneous, with heavy reliance on self-reported measures, associations with sound, convergent levels of evidence were found for: 1) parental rule-setting for bedtimes and parent sleep behaviours with longer sleep duration in adolescents; 2) healthy parent sleep and family functioning with better adolescent sleep quality; and 3) parental warmth with better adolescent daytime functioning. Effect sizes were in the small to moderate range. The identified parental factors are recommended targets for inclusion in parenting programs to support adolescent sleep, however, would require validation in intervention studies. Opportunities for research are outlined for the identified parental factors, sleep domains with limited evidence, and better understanding the mechanisms or possible moderators in the associations between parental factors and sleep outcomes.

Maternal Sleep Quality is Associated with Personal and Parenting Weight-Related Behaviors

Mothers of young children tend to report poor-quality sleep, yet little is known about links between maternal sleep quality and weight-related behaviors and parenting practices. Thus, mothers of preschoolers completed an online cross-sectional survey assessing their sleep, physical activity, dietary behaviors, eating styles, child feeding practices, family meal behaviors, and health parameters. Comparisons by sleep quality using the Pittsburgh Sleep Quality Index item (i.e., very bad/bad, n = 87; fair, n = 255; and good/very good, n = 193) revealed mothers with poor-quality sleep had weight-related behaviors associated with higher Body Mass Index (BMI) (lower physical activity, fewer fruits/vegetables, more emotional and disinhibited eating). Poor-quality sleepers also engaged in parenting practices contrary to recommendations, such as less frequent modeling of healthy eating and physical activity, more control of child feeding, and fewer family meals. Mothers reporting poor-quality sleep tended to have lower parenting self-efficacy, poorer overall health status, more days of poor mental and physical health, greater depression, more stress, and higher BMIs. Future nutrition research should establish the directionality between sleep quality and health behaviors. Future interventions should help mothers develop strategies for improving sleep quality, such as increased physical activity and fruit and vegetable intake, and helping mothers realize how their sleep quality may affect parenting practices.

Study protocol for a 9-month randomised controlled trial assessing the effects of almonds versus carbohydrate-rich snack foods on weight loss and weight maintenance

INTRODUCTION

Epidemiological studies indicate an inverse association between nut consumption and body mass index (BMI). However, clinical trials evaluating the effects of nut consumption compared with a nut-free diet on adiposity have reported mixed findings with some studies reporting greater weight loss and others reporting no weight change. This paper describes the rationale and detailed protocol for a randomised controlled trial assessing whether the inclusion of almonds or carbohydrate-rich snacks in an otherwise nut-free energy-restricted diet will promote weight loss during 3 months of energy restriction and limit weight regain during 6 months of weight maintenance.

METHODS AND ANALYSIS

One hundred and thirty-four adults aged 25-65 years with a BMI of 27.5-34.9 kg/m² will be recruited and randomly allocated to either the almond-enriched diet (AED) (15% energy from almonds) or a nut-free control diet (NFD) (15% energy from carbohydrate-rich snack foods). Study snack foods will be provided. Weight loss will be achieved through a 30% energy restriction over 3 months, and weight maintenance will be encouraged for 6 months by increasing overall energy intake by ~120-180 kcal/day (~500-750kJ/day) as required. Food will be self-selected, based on recommendations from the study dietitian. Body composition, resting energy expenditure, total daily energy expenditure (via doubly labelled water), physical activity, appetite regulation, cardiometabolic health, gut microbiome, liver health, inflammatory factors, eating behaviours, mood and personality, functional mobility and pain, quality of life and sleep patterns will be measured throughout the 9-month trial. The effects of intervention on the outcome measures over time will be analysed using random effects mixed models, with treatment (AED or NFD) and time (baseline, 3 months and 9 months) being the between and within factors, respectively in the analysis.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the University of South Australia Human Research Ethics Committee (201436). Results from this trial will be disseminated through publication in peer-reviewed journals, national and international presentations.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12618001861246).

Objectively measured sleep and telomere length in a population-based cohort of children and midlife adults

STUDY OBJECTIVES

Poor sleep patterns in older adults are associated with chromosomal telomere shortening, a marker of cellular senescence. However, studies have relied on self-reported sleep characteristics, with few data for younger individuals. We investigated whether sleep measured via actigraphy was cross-sectionally associated with telomere length in children and midlife adults.

METHODS

A population-based sample of 1874 11-12 year olds and midlife adults (mean age 44 years, SD 5.1) had biological and physical assessments at centers across Australia in 2015-2016. Sleep characteristics, including duration, onset, offset, day-to-day variability, and efficiency, were derived from actigraphy. Relative telomere length (T/S ratio) was measured by quantitative polymerase chain reaction on genomic DNA from peripheral blood. Multivariable regression models estimated associations, adjusting for prespecified confounders.

RESULTS

Both sleep and telomere data were available for 728 children and 1070 adults. Mean (SD) T/S ratio was 1.09 (0.55) in children and 0.81 (0.38) in adults. T/S ratio was not predicted by sleep duration (β 0.04, 95% confidence interval [CI] -0.02 to 0.09, p = .16, children; β -0.004, 95% CI -0.03 to 0.02, p = .70, adults) or most other sleep metrics. The only exception was a weak association between later sleep timing (the midpoint of sleep onset and offset) and longer telomeres in adults (β 0.03, 95% CI 0.01 to 0.06, p = .01).

CONCLUSIONS

Objective sleep characteristics show no convincing associations with telomere length in two largely healthy populations up to at least midlife. Sleep-telomere associations may be a late-life occurrence or may present only with a trigger such as presence of other morbidities.

Psychometric properties of the PERMA Profiler for measuring wellbeing in Australian adults

INTRODUCTION

This study evaluated the psychometric properties of the PERMA Profiler, a 15-item self-report measurement tool designed to measure Seligman's five pillars of wellbeing: Positive emotions, Relationships, Engagement, Meaning, and Accomplishment.

METHODS

Australian adults (N = 439) completed the PERMA Profiler and measures of physical and mental health (SF-12), depression, anxiety, stress (DASS 21), subjective physical activity (Active Australia Survey), and objective activity and sleep (GENEActiv accelerometer). Internal consistency was examined using Cronbach's alpha and associations between theoretically related constructs examined using Pearson's correlation. Model fit in comparison with theorised models was examined via Confirmatory Factor Analysis.

RESULTS

Results indicated acceptable internal consistency for overall PERMA Profiler scores and all subscales (α range = 0.80-0.93) except Engagement (α = 0.66). Moderate associations were found between PERMA Profiler wellbeing scores with subjective constructs (e.g. depression, anxiety, stress; r = -0.374 - -0.645, p = <0.001) but not objective physical activity or sleep. Data failed to meet model fit criteria for neither the theorised five-factor nor an alternative single-factor structure.

CONCLUSIONS

Findings were mixed, providing strong support for the scale's internal consistency and moderate support for congervent and divergent validity, albeit not in comparison to objectively captured activity outcomes. We could not replicate the theorised data structure nor an alternative, single factor structure. Results indicate insufficient psychometric properties of the PERMA Profiler.

Population health bio-phenotypes in 11-12 year old children and their midlife parents: Growing Up in Australia's Child Health CheckPoint

In an ambitious undertaking, Growing Up in Australia's Child Health CheckPoint streamlined and implemented wide-ranging population phenotypes and biosamples relevant to non-communicable diseases in nearly 1900 parent-child dyads throughout Australia at child aged 11-12 years. This BMJ Open Special Issue describes the methodology, epidemiology and parent-child concordance of 14 of these phenotypes, spanning cardiovascular, respiratory, bone, kidney, hearing and language, body composition, metabolic profiles, telomere length, sleep, physical activity, snack choice and health-related quality of life. The Special Issue also includes a cohort summary and study methodology paper.

Child Health CheckPoint: cohort summary and methodology of a physical health and biospecimen module for the Longitudinal Study of Australian Children

OBJECTIVES

'Growing Up in Australia: The Longitudinal Study of Australian Children' (LSAC) is Australia's only nationally representative children's longitudinal study, focusing on social, economic, physical and cultural impacts on health, learning, social and cognitive development. LSAC's first decade collected wide-ranging repeated psychosocial and administrative data; here, we describe the Child Health CheckPoint, LSAC's dedicated biophysical module.

DESIGN, SETTING AND PARTICIPANTS

LSAC recruited a cross-sequential sample of 5107 infants aged 0-1 year and a sample of 4983 children aged 4-5 years in 2004, since completing seven biennial visits. CheckPoint was a cross-sectional wave that travelled Australia in 2015-2016 to reach LSAC's younger cohort at ages 11-12 years between LSAC waves 6 and 7. Parent-child pairs participated in comprehensive assessments at 15 Assessment Centres nationwide or, if unable to attend, a shorter home visit.

MEASURES

CheckPoint's intergenerational, multidimensional measures were prioritised to show meaningful variation within normal ranges and capture non-communicable disease (NCD) phenotype precursors. These included anthropometry, physical activity, fitness, time use, vision, hearing, and cardiovascular, respiratory and bone health. Biospecimens included blood, saliva, buccal swabs (also from second parent), urine, hair and toenails. The epidemiology and parent-child concordance of many measures are described in separate papers.

RESULTS

1874 (54% of eligible) parent-child pairs and 1051 second parents participated. Participants' geographical distribution mirrored the broader Australian population; however, mean socioeconomic position and parental education were higher and fewer reported non-English-speaking or Indigenous backgrounds. Application of survey weights partially mitigates that the achieved sample is less population representative than previous waves of LSAC due to non-random attrition. Completeness was uniformly high for phenotypic data (>92% of eligible), biospecimens (74%-97%) and consent (genetic analyses 98%, accessing neonatal blood spots 97%, sharing 96%).

CONCLUSIONS

CheckPoint enriches LSAC to study how NCDs develop at the molecular and phenotypic levels before overt disease emerges, and clarify the underlying dimensionality of health in childhood and mid-adulthood.