Prospective associations between sedentary time, sleep duration and adiposity in adolescents

The Longitudinal Interplay between Sleep, Anthropometric Indices, Eating Behaviors, and Nutritional Aspects: A Systematic Review and Meta-Analysis

Sleep is fundamental for adolescents' healthy development but undergoes dramatic changes in quantity and quality due to the conflict between biological and social rhythms. Insufficient sleep has been associated with worse physical health status and irregular eating behaviors in adolescents. This review aims to systematically synthesize the longitudinal associations between adolescents' sleep dimensions (i.e., duration, timing, quality, and insomnia symptoms) and physical health indicators (i.e., anthropometric indices, fat percentage, and risk of obesity), eating behaviors, and nutritional aspects (i.e., type of diet related to the intake of specific foods and nutrients, amount and timing of food consumption, energy expenditure). A total of 28 longitudinal studies were included. The meta-analytic results showed that longer sleep duration, better sleep quality, and lower insomnia symptoms were associated with lower BMI and fat percentage and that shorter sleep duration (<7 h) and lower sleep quality were associated with a higher risk of obesity. Conversely, anthropometric indices were not related to sleep over time. Limited literature examined the bidirectional association between adolescents' sleep and their eating behaviors and nutritional aspects. Such knowledge sheds new light on the role of sleep for adolescents' health, highlighting the need to examine further the interplay between these variables.

Shorter sleep among adolescents is associated with lower fruit and vegetable consumption the following day

BACKGROUND

Insufficient sleep has been associated with weight gain and metabolic dysregulation, with one suggested mechanism being through reduction in diet quality. Experimental evidence supports a causal effect of sleep timings on diet but this may not be applicable to a free-living adolescent population. In this analysis we use daily measures of sleep timings and diet quality, to examine the effect of sleep duration and timing on diet quality the following day among free-living adolescents.

METHODS

The ROOTS study is a prospective cohort recruited from secondary schools in Cambridgeshire and Suffolk (UK). Participants (n = 815) at mean age 15.0y (SD 0.3y) completed a diet diary and wore a combined heart rate and accelerometer device over 4 consecutive days. Sleep duration and timing (midpoint) were derived from acceleration and heart rate traces, while daily energy density and fruit and vegetable intake were calculated from dietary data. Analyses were performed at day-level (1815 person-days). Multilevel random effects models were used to test associations between sleep each night and subsequent day diet, with daily sleep and diet measures nested within individuals and schools, and adjusted for day-level and individual-level confounding variables.

RESULTS

Adolescents slept a mean of 7.88 hrs (SD 1.10) per night, reporting a mean energy density of 2.12 kcal/g (SD 0.48) and median energy-adjusted daily fruit and vegetable intake of 137.3 g (IQR 130.4). One hour shorter sleep duration was associated with lower intake of fruit and vegetables (-6.42 g, 95%CI -1.84, -10.99) the following day. An association with higher dietary energy density (0.016 kcal/g, 95%CI 0.034, -0.002) the following day was observed but did not reach statistical significance. Sleep timing was not associated with either fruit and vegetable intake (-2.52 g/d, 95%CI -7.66, 2.62) or dietary energy density (-0.001 kcal/g, 95%CI -0.022, 0.020).

CONCLUSIONS

Our observational findings from a free-living adolescent population support the experimental evidence for a causal role of sleep on diet, with shorter sleep duration at night leading to a small decrease in diet quality the following day. These findings support experimental evidence to suggest inclusion of sleep duration as one component of interventions designed to improve diet quality and weight status in adolescents.

Subjective and Behavioral Impulsivity Differentially Moderate Within- and Between-Person Associations Between Physical Activity and Alcohol Consumption

OBJECTIVE

Evidence indicates a counterintuitive positive relationship between physical activity and alcohol consumption, suggesting that people who engage in more physical activity consume more alcohol. Impulsivity, which has a well-documented role in alcohol use disorders, has been shown to moderate the between-person physical activity-drinking association among emerging adults. However, only a handful of studies have explored within-person associations of physical activity and drinking and potential moderators of this relationship. The current study evaluated the effects of both subjective and behavioral impulsivity on the within- and between-person association between physical activity and alcohol consumption among college students.

METHOD

Undergraduate students (N = 250) between ages 18 and 25 years were asked to report their daily physical activity and drinking over 21 days. Physical activity was also recorded objectively through Pacer, a smartphone app. Subjective impulsivity was assessed using the UPPS-P Impulsive Behavior Scale, and behavioral impulsivity was evaluated using the Balloon Analogue Risk Task.

RESULTS

Within- and between-subject physical activity-drinking associations were differentially moderated by behavioral impulsivity and self-reported impulsivity. For instance, behavioral impulsivity moderated the within-person association between drinking and self-reported vigorous physical activity, whereas negative urgency moderated the between-person association between drinking and objective physical activity.

CONCLUSIONS

Impulsivity, whether measured subjectively or behaviorally, significantly moderates the physical activity-alcohol consumption association. Importantly, this effect operates differently when predicting variation in behavior within individuals as compared with predicting differences in behavior between individuals.

Device-measured sleep onset and duration in the development of depressive symptoms in adolescence

BACKGROUND

Sleep deprivation in adolescence is increasing in prevalence and may be linked to subsequent depression. Findings regarding associations between sleep duration, sleep onset time, and the development of depressive symptoms over time in adolescents are mixed, and rely on subjective measures of sleep.

METHODS

Sleep onset and duration were assessed using a combined heart rate monitor and accelerometer and self-report in 688 participants from the ROOTS study at age 15. Participants reported depressive symptoms at ages 14.5, 16, and 17.5, using the Mood and Feelings Questionnaire. Latent growth curve modelling was used to model development of depressive symptoms and test associations with baseline sleep onset and duration.

RESULTS

Cross-sectionally, falling asleep later and shorter sleep duration were both associated with higher depressive symptoms in males and females, using both device-measured and self-reported sleep. There were no longitudinal associations between baseline sleep duration and change in depressive symptoms. A later sleep onset-time was associated with a decrease in depressive symptoms over time, in females only, using device-measured sleep only.

LIMITATIONS

The current sample was more economically advantaged and ethnically white than the UK average, and with lower MFQ symptoms than the original cohort, which may reduce generalisability.

CONCLUSIONS

Adolescents who fall asleep later or sleep less have higher levels of depressive symptoms cross-sectionally, but do not show increases in depressive symptoms over time. Interventions targeting sleep onset and duration in adolescence may improve mental health in the short-term but the possibility of reverse causality should be explored further.

The Causal Relationships Between Sleep-related Phenotypes and Body Composition: A Mendelian Randomized Study

BACKGROUND

Despite cumulative evidence showing obesity is associated with changes in sleep quality and quantity, the study about the relationships between sleep and body composition is scarce, and whether the relationship is causal remains unknown. In this study, we examined whether there are causal associations between sleep and body composition.

METHODS

First, we estimated genetic correlations between sleep-related phenotypes and body composition using the linkage disequilibrium score regression (LDSC). Mendelian randomization (MR) analysis was then conducted to test 2-way causal relationships on phenotypes with significant genetic associations. Finally, Bayesian colocalization (COLOC) analysis was performed to calculate the posterior probability of causal variation and identify the common genes to verify the results of MR.

RESULTS

For the LDSC analysis, we observed some significant genetic correlations (rG), such as snoring and right leg fat mass (rG = 0.376, P = 7.21 × 10-80). For the MR analysis, we identified some significant causal relationships, such as snoring is the causal risk factor for whole-body fat-free mass (Pweighted median = 1.28 × 10-6, PMR-PRESSO = 1.35 × 10-7), dozing is the causal risk factor for right leg fat mass (Pweighted median = 9.22 × 10-4, PMR-PRESSO = 9.55 × 10-4), and right arm fat mass (Pweighted median = 1.11 × 10-40, PMR-PRESSO = 4.93 × 10-55) is the causal risk factor for snoring. For the COLOC analysis, we identified rs143384 mapping on GDF5 and 6 overlapped single nucleotide polymorphisms (eg, rs1421085, rs11642015) mapping on FTO.

CONCLUSION

Our study identified the causal relationships between sleep-related phenotypes and body composition. These findings may give insights into the mechanism of sleep disturbances and provide novel therapeutic targets.

Association of maternal prenatal depression and anxiety with toddler sleep: the China-Anhui Birth Cohort study

Maternal prenatal depression is associated with child sleep. We investigated whether maternal depression comorbid with anxiety worsens toddler's sleep problems in a prospective cohort study. A total of 1583 mother-infant pairs from the China-Anhui Birth Cohort study were examined. The participants completed the Center for Epidemiologic Studies Depression Scale (CES-D) and Self-Rating Anxiety Scale (SAS) at 30-34 weeks of gestation, and the Edinburgh Postnatal Depression Scale (EPDS) at 3-month postpartum. Toddler's sleep was assessed by the Brief Infant Sleep Questionnaire (BISQ) at 30 months old. Logistic regression models were used to investigate the associations between prenatal depression and anxiety and toddler's sleep, while adjusting for maternal gestational age, education, family income, alcohol use, premature birth, fetal growth restriction, mode of delivery, postnatal depression, and 3-month breastfeeding. In total, 9.0% of participants reported prenatal depression comorbid with anxiety symptoms, and the prevalence of depression, anxiety was 6.7% and 7.3%, respectively. Compared with mothers without depression and anxiety, maternal depression combined with anxiety were significantly associated with shorter total sleep duration (11.16 ± 1.06 h), longer settling time (29.25 ± 23.57 min), and higher risk of toddlers' sleep problems assessed by BISQ (OR = 2.09, 95% CI: 1.22-3.57) or parental report (OR = 1.84, 95% CI: 1.22-2.77). However, there was no significant association between maternal postnatal depression and toddler sleep behaviors. Maternal prenatal depression comorbid with anxiety significantly associated with poorer toddler's sleep. Strategies to regulate prenatal mood status should be considered during prenatal health care to improve children's sleep development.

A collaborative approach to adopting/adapting guidelines. The Australian 24-hour movement guidelines for children (5-12 years) and young people (13-17 years): An integration of physical activity, sedentary behaviour, and sleep

Abstract

Background

In 2018, the Australian Government updated the Australian Physical Activity and Sedentary Behaviour Guidelines for Children and Young People. A requirement of this update was the incorporation of a 24-hour approach to movement, recognising the importance of adequate sleep. The purpose of this paper was to describe how the updated Australian 24-Hour Movement Guidelines for Children and Young People (5 to 17 years): an integration of physical activity, sedentary behaviour and sleep were developed and the outcomes from this process.

Methods

The GRADE-ADOLOPMENT approach was used to develop the guidelines. A Leadership Group was formed, who identified existing credible guidelines. The Canadian 24-Hour Movement Guidelines for Children and Youth best met the criteria established by the Leadership Group. These guidelines were evaluated based on the evidence in the GRADE tables, summaries of findings tables and recommendations from the Canadian Guidelines. We conducted updates to each of the Canadian systematic reviews. A Guideline Development Group reviewed, separately and in combination, the evidence for each behaviour. A choice was then made to adopt or adapt the Canadian recommendations for each behaviour or create de novo recommendations. We then conducted an online survey (n=237) along with three focus groups (n=11 in total) and 13 key informant interviews. Stakeholders used these to provide feedback on the draft guidelines.

Results

Based on the evidence from the Canadian systematic reviews and the updated systematic reviews in Australia, the Guideline Development Group agreed to adopt the Canadian recommendations and, apart from some minor changes to the wording of good practice statements, maintain the wording of the guidelines, preamble, and title of the Canadian Guidelines. The Australian Guidelines provide evidence-informed recommendations for a healthy day (24-hours), integrating physical activity, sedentary behaviour (including limits to screen time), and sleep for children (5-12 years) and young people (13-17 years).

Conclusions

To our knowledge, this is only the second time the GRADE-ADOLOPMENT approach has been used to develop movement behaviour guidelines. The judgments of the Australian Guideline Development Group did not differ sufficiently to change the directions and strength of the recommendations and as such, the Canadian Guidelines were adopted with only very minor alterations. This allowed the Australian Guidelines to be developed in a shorter time frame and at a lower cost. We recommend the GRADE-ADOLOPMENT approach, especially if a credible set of guidelines that was developed using the GRADE approach is available with all supporting materials. Other countries may consider this approach when developing and/or revising national movement guidelines.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-021-01236-2.

Independent and combined influences of physical activity, screen time, and sleep quality on adiposity indicators in Indian adolescents

BACKGROUND

Inadequate physical activity (PA), excess screen time (ST), and sub-optimal sleep quality tend to co-occur during adolescence. Yet, little is known about the associations of these behaviors as a cluster with adiposity indicators in Indian adolescents. This study aimed to evaluate the independent and combined influences of PA, ST, and sleep quality on body mass index (BMI) and waist to height ratio (WHtR) in 10-15 years old adolescents in Mumbai, India. A secondary aim was to explore if these influences vary between sexes.

METHODS

Cross-sectional study. Adolescents (n = 772, mean age 13.2 (1.4) years) reported frequency and duration of moderate to vigorous PA (MVPA) and time spent using screens on a previously validated instrument. Sleep quality was estimated using the Pittsburg Sleep Quality Index (PSQI). Weight, height, and waist circumference were measured. Mixed effect logistic regression analyses were performed to explore associations between adiposity indicators (BMI z scores > +1SD and WHtR > 0.5) and unhealthy behaviors (PA < 60 min/d, ST > 120 min/d and PSQI scores > 5), stratified by sex.

RESULTS

The combined prevalence of overweight and obesity was 38.3%. Overall, 62.0 and 85.0% reported MVPA< 60 min/d and ST > 120 min/d respectively. Girls reported higher ST (218.21 (69.01) min/d) as compared to boys (165.3 (101.22) min/d, p < 0.001). Clustering of low PA and excess ST was observed in 69.2% and of all three unhealthy behaviors in 18.8%. Among girls, MVPA < 60 min/d (OR = 1.78, 95% CI 1.54-1.92, p < 0.001) and PSQI scores > 5 (OR = 2.01, 95% CI 1.78-2.25, p < 0.001) predicted increased BMI. The odds of overweight/obesity were 2.10 times higher in boys reporting low PA and 4.13 times higher in those with low PA+ ST > 120 min/d. Clustering of all three unhealthy behaviors increased prevalence of obesity in both sexes.

CONCLUSIONS

The results indicated a co-existence of multiple unhealthy lifestyle factors of obesity and that clustering of these behaviors can further aggravate obesity risk as compared to their independent effects. Integrated interventions that leverage the cumulative benefits of being active, less sedentary and sufficient sleep are warranted to facilitate greater improvements in obesity risk behaviors.

Associations of diarised sleep onset time, period and duration with total and central adiposity in a biethnic sample of young children: the Born in Bradford observational cohort study

OBJECTIVES

To investigate associations of parent-reported sleep characteristics with adiposity levels in a biethnic sample of young children.

DESIGN

A cross-sectional observational study.

SETTING

The Born in Bradford 1000 study, UK.

PARTICIPANTS

Children aged approximately 18 months (n=209; 40.2% South Asian; 59.8% white) and 36 months (n=162; 40.7% South Asian; 59.3% white).

PRIMARY AND SECONDARY OUTCOME MEASURES

Children's body mass index (BMI) z-score, sum of two-skinfolds (triceps and subscapular) and waist circumference. Adjusted regression was used to quantify associations of sleep parameters with adiposity stratified by ethnicity and age group. The results are beta coefficients (95% CIs) and unless otherwise stated represent the difference in outcomes for every 1-hour difference in sleep parameters.

RESULTS

The average sleep onset time was markedly later in South Asian (21:26±68 min) than white children (19:41±48 min). Later sleep onset was associated with lower BMI z-score (-0.3 (-0.5 to -0.0)) and sum of two-skinfolds (-1.5 mm (-2.8 mm to -0.2 mm)) in white children aged 18 months and higher BMI z-score in South Asian children aged 36 months (0.3 (0.0-0.5)). Longer sleep duration on weekends than weekdays was associated with higher BMI z-score (0.4 (0.1-0.8)) and waist circumference (1.2 cm (0.3-2.2 cm)) in South Asian children aged 18 months, and later sleep onset on weekends than weekdays was associated with larger sum of two-skinfolds (1.7 mm (0.3-3.1 mm)) and waist circumference (1.8 cm (0.6-2.9 cm)). Going to sleep ≥20 min later on weekends than weekdays was associated with lower waist circumference in white children aged 18 months (-1.7 cm (-3.2 cm to -0.1 cm)).

CONCLUSIONS

Sleep timing is associated with total and central adiposity in young children but associations differ by age group and ethnicity. Sleep onset times and regular sleep schedules may be important for obesity prevention.

Sleep, social behaviour and food consumption of schoolchildren of a large Brazilian city

OBJECTIVE

To explore the impact of inadequate sleep and associated factors on the social behaviour and food consumption of children and adolescents.

DESIGN

Cross-sectional study.

SETTING

Sleep information, social behaviour (Strengths and Difficulties Questionnaire), food consumption, demography, nutritional status, lifestyle, and biochemical tests were investigated.

PARTICIPANTS

School children in the 4th grade of the municipal school system of a large Brazilian city.

RESULTS

Of a total of 797 schoolchildren, 50·9 % were female, with a median age of 9·7 (9·5-10·0) years old and an energy consumption of 7613·6 (5982·7-9766·2) kJ. It was determined that 31·6 % were overweight, and 76·8 % reported insufficient weekly practice of physical activity. A median of 9·6 (8·9-10·5) h of sleep (lower values on weekdays: 9·3 v. 10·5 h, P < 0·001) was recorded. In addition, 27 % of the individuals who experienced inadequate sleep (<9 h) engaged in longer screen time daily (≥2 h/d) (P = 0·05), had an inadequate bedtime (> 22 h) or adequate wake-up time (5-7 h), studied in the morning (P < 0·001) and never took a shower before school (P < 0·001). Of the entire sample, 9·9 % had poor or very poor sleep quality and a greater probability of sleep talking regularly, had difficulty falling asleep, and engaged in inadequate social behaviour while experiencing these conditions compared with those with positive sleep quality. There was no association between sleep and the other variables investigated.

CONCLUSIONS

Sleep impairment contributed to changes in sleep and social behaviour in schoolchildren. The findings of this study may reinforce the importance of developing actions to promote adequate sleep and a healthy lifestyle at school age.

A Digital Intervention for Australian Adolescents Above a Healthy Weight (Health Online for Teens): Protocol for an Implementation and User Experience Study

Background

More than one-fourth of Australian adolescents are overweight or obese, with obesity in adolescents strongly persisting into adulthood. Recent evidence suggests that the mid-teen years present a final window of opportunity to prevent irreversible damage to the cardiovascular system. As lifestyle behaviors may change with increased autonomy during adolescence, this life stage is an ideal time to intervene and promote healthy eating and physical activity behaviors, well-being, and self-esteem. As teenagers are prolific users and innate adopters of new technologies, app-based programs may be suitable for the promotion of healthy lifestyle behaviors and goal setting training.

Objective

This study aims to explore the reach, engagement, user experience, and satisfaction of the new app-based and Web-based Health Online for Teens (HOT) program in a sample of Australian adolescents above a healthy weight (ie, overweight or obese) and their parents.

Methods

HOT is a 14-week program for adolescents and their parents. The program is delivered online through the Moodle app–based and website-based learning environment and aims to promote adolescents’ lifestyle behavior change in line with Australian Dietary Guidelines and Australia’s Physical Activity and Sedentary Behaviour Guidelines for Young People (aged 13-17 years). HOT aims to build parental and peer support during the program to support adolescents with healthy lifestyle behavior change.

Results

Data collection for this study is ongoing. To date, 35 adolescents and their parents have participated in one of 3 groups.

Conclusions

HOT is a new online-only program for Australian adolescents and their parents that aims to reduce cardiovascular disease risk factors. This protocol paper describes the HOT program in detail, along with the methods to measure reach, outcomes, engagement, user experiences, and program satisfaction.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN12618000465257; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374771

International Registered Report Identifier (IRRID)

DERR1-10.2196/13340

Skipping breakfast is associated with adiposity markers especially when sleep time is adequate in adolescents

Adolescence is a critical stage of development and has an important influence on energy balance-related behaviours (EBRBs). When adolescents are associated with obesity it can lead to increased cardiometabolic risk. Here we assess if EBRBs adopted by adolescents included in a subsample are associated with markers of total and abdominal adiposity in a multicentre European study, Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA-CSS) and a Brazilian study, Brazilian Cardiovascular Adolescent Health (BRACAH study), and whether sleep duration influence the association between skipping breakfast, physical activity and sedentary behaviours, with total and abdominal obesity (AO). Multilevel linear regression models using fixed and random intercepts were used to analyse the association between markers of obesity and EBRBs. Skipping breakfast was the prevalent behaviour in association with obesity among European and Brazilian boys besides European girls, even after stratification by sleep time. Moreover, European boys who slept properly and skipped breakfast had an increased waist circumference (WC), while body mass index (BMI) increased in Brazilian boys. Among Brazilian boys less sleep was protective for total obesity (β = −0.93 kg/m²; 95% CI: −1.80; −0.07). European girls when they were more sedentary, showed an increase in WC, especially for those who reported they slept adequately. Skipping breakfast was associated with total and AO in adolescents independent of sleep duration.

Longitudinal Changes in Sitting Patterns, Physical Activity, and Health Outcomes in Adolescents

This study examined two-year changes in patterns of activity and associations with body mass index (BMI) and waist circumference (WC) among adolescents. Inclinometers (activPAL) assessed sitting, sitting bouts, standing, stepping, and breaks from sitting. ActiGraph-accelerometers assessed sedentary time (SED), light-intensity physical activity (LIPA, stratified as low- and high-LIPA), and moderate-to-vigorous physical activity (MVPA). Anthropometric measures were objectively assessed at baseline and self-reported at follow-up. Data from 324 and 67 participants were obtained at baseline and follow-up, respectively. Multilevel mixed-effects linear regression models examined changes over time, and associations between baseline values and BMI and WC at follow-up. There were significant increases in BMI (0.6 kg/m²) and durations of prolonged sitting (26.4 min/day) and SED (52 min/day), and significant decreases in stepping (−19 min/day), LIPA (−33 min/day), low-LIPA (−26 min/day), high-LIPA (−6.3 min/day), MVPA (−19 min/day), and the number of breaks/day (−8). High baseline sitting time was associated (p = 0.086) with higher BMI at follow-up. There were no significant associations between baseline sitting, prolonged sitting, LIPA, or MVPA with WC. Although changes in daily activity patterns were not in a favourable direction, there were no clear associations with BMI or WC. Research with larger sample sizes and more time points is needed.

Gender-dependent association between sleep duration and overweight incidence in CHINESE school children: a national follow-up study

BACKGROUND

The relationship between sleep duration and overweight risk remains unexplored among Chinese children. This study aims to evaluate this association in a national investigation with school-aged population.

METHODS

There were 18,302 normal weight children in this Chinese national study which conducted during 2013-2014 included in the research. Anthropometric measurements were performed both at baseline and after 6-9 month. Sleep duration, physical activity, food intake and social economic information were collected by self-report questionnaire. Overweight was defined according to the updated Chinese criterion. Cox regression was used to evaluate the relationships between sleep duration and overweight incidence with multivariable adjusted.

RESULTS

In total, there were 443 new overweight cases recorded at the end of observation. Overweight incidence with greater than 9 h (long sleep duration, LSD), 7 to 9 h (middle sleep duration, MSD), and less than 7 h of sleep (short sleep duration, SSD) were 2.7, 3.1 and 3.3% respectively. Stratified by gender and compared with LSD, the hazard ratio (HR) of overweight for females with MSD was 1.60 (95% CI: 1.02-2.52). Stratified by age and gender, the HR in the group of MSD was 2.13 (1.20-3.77) in female aged 6-10 years and 0.24 (0.06-0.93) in female aged 15-17 years.

CONCLUSION

The association between short sleep duration and overweight is age- and gender dependent. In group of small age and elder age, girls' adiposity states are independently associated with sleep duration. Sleep recommendation is a potential preventive action for overweight/obesity among girls.

Effect of Sleep Duration, Diet, and Physical Activity on Obesity and Overweight Elementary School Students in Shanghai

BACKGROUND

This was a cross-sectional survey to investigate the relationship of age, parent education, sleep duration, physical activity, and dietary habits with overweight or obesity in school-age children in Shanghai.

METHODS

The survey gathered information from 13,001 children in grades 1 through 5 (age 6 to 10 years) among 26 elementary schools in 7 districts. Activity level was evaluated using the International Children's Leisure Activities Study Survey Questionnaire (CLASS-C). The definitions of normal, overweight, and obese were adjusted for each age.

RESULTS

Logistic regression analysis indicated that age, being male, having ≤10 hours of sleep on non-school days, eating ≥1 vegetable/day, or drinking ≥1 sugar-sweetened drink/day increased the risk for a child being overweight or obese compared with having >10 hours of sleep or ≤3 vegetables or ≤3 sugar-sweetened drinks/month (p ≤ .008). Having >2 hours of outdoor activities on non-school days reduced the risk of being overweight or obese compared with ≤2 hours of outdoor activities on non-school days (p < .001).

CONCLUSIONS

We found that age, sex, sleep, and some dietary habits impacted weight, and suggests that specific cultural and economic factors may impact risk of a child being overweight or obese.

Physical Activity Duration but Not Energy Expenditure Differs between Daily and Intermittent Breakfast Consumption in Adolescent Girls: A Randomized Crossover Trial

Background

It is not known whether breakfast frequency affects physical activity (PA) in children or adolescents.

Objective

This study examined the effect of daily compared with intermittent breakfast consumption on estimated PA energy expenditure (PAEE) in adolescent girls.

Methods

Under a randomized crossover design, 27 girls [mean ± SD age: 12.4 ± 0.5 y, body mass index (in kg/m2): 19.3 ± 3.0] completed two 7-d conditions. A standardized breakfast (∼1674 kJ) was consumed every day before 0900 in the daily breakfast consumption (DBC) condition. The standardized breakfast was consumed on only 3 d before 0900 in the intermittent breakfast consumption (IBC) condition, alternating with breakfast omission on the remaining 4 d (i.e., only water consumed before 1030). Combined heart rate accelerometry was used to estimate PAEE throughout each condition. Statistical analyses were completed by using condition × time of day repeated-measures ANOVA. The primary outcome was PAEE and the secondary outcome was time spent in PA.

Results

Daily estimated PAEE from sedentary or light-, moderate-, or vigorous-intensity PA and total PAEE were not significantly different between the conditions. The condition × time of day interaction for sedentary time (P = 0.05) indicated that the girls spent an additional 11.5 min/d being sedentary in the IBC condition compared with the DBC condition from 1530 to bedtime (P = 0.04). Light PA was 19.8 min/d longer in the DBC condition than in the IBC condition (P = 0.05), which was accumulated from waking to 1030 (P = 0.04) and from 1530 to bedtime (P = 0.03). There were no significant differences in time spent in moderate PA or vigorous PA between the conditions.

Conclusions

Adolescent girls spent more time in light PA before 1030 and after school and spent less time sedentary after school when a standardized breakfast was consumed daily than when consumed intermittently across 7 d. However, breakfast manipulation did not affect estimated daily PAEE. This trial was registered at www.isrctn.com as ISRCTN74579070.

Daily sitting time associated with the risk of metabolic syndrome in Korean adolescents

BACKGROUND

This study aimed to investigate the relationship between daily sitting time and the risk of metabolic syndrome in Korean adolescents.

METHODS

Data from 486 adolescents aged 12-18 years were obtained from national surveys. Daily sitting time was measured using questionnaires and divided into three intervals: <8 h; 8-12 h; and ≥12 h.

RESULTS

The mean daily sitting time and prevalence of positive metabolic components were 620.9±9.9 min/day and 45.5±2.7%, respectively. In a multivariate logistic regression analysis, adolescents who sat longer were more likely to have metabolic components (p<0.05), independent of age, sex, area of residence, sleeping time and body mass index.

CONCLUSIONS

Longer daily sitting time appears to be associated with an increased risk of metabolic syndrome in adolescents. These findings highlight the need to focus on reducing sitting time for all adolescents, not just for those at risk of obesity.

Sleep Duration and Adiposity in Early Childhood: Evidence for Bidirectional Associations from the Born in Bradford Study

Study Objectives:

To examine independent associations of sleep duration with total and abdominal adiposity, and the bidirectionality of these associations, in a young biethnic sample of children from a disadvantaged location.

Methods:

Child sleep duration (h/day) was parent-reported by questionnaire and indices of total (body weight, body mass index, percent body fat (%BF), sum of skinfolds) and abdominal adiposity (waist circumference) were measured using standard anthropometric procedures at approximately 12, 18, 24, and 36 months of age in 1,338 children (58% South Asian; 42% White). Mixed effects models were used to quantify independent associations (expressed as standardised β-coefficients (95% confidence interval (CI)) of sleep duration with adiposity indices using data from all four time-points. Factors considered for adjustment in models included basic demographics, pregnancy and birth characteristics, and lifestyle behaviours.

Results:

With the exception of the sum of skinfolds, sleep duration was inversely and independently associated with indices of total and abdominal adiposity in South Asian children. For example, one standard deviation (SD) higher sleep duration was associated with reduced %BF by -0.029 (95% CI: −0.053, −0.0043) SDs. Higher adiposity was also independently associated with shorter sleep duration in South Asian children (for example, %BF: β = -0.10 (-0.16, -0.028) SDs). There were no significant associations in White children.

Conclusions:

Associations between sleep duration and adiposity are bidirectional and independent among South Asian children from a disadvantaged location. The results highlight the importance of considering adiposity as both a determinant of decreased sleep and a potential consequence.

Cross-sectional and prospective mediating effects of dietary intake on the relationship between sedentary behaviour and body mass index in adolescents

BACKGROUND

Cross-sectional evidence suggests TV viewing, but not objectively-measured sedentary time or bouts of sedentary time, is consistently associated with body mass index (BMI) in adolescents. However, it is unclear whether dietary intake is a potential mediator of these relationships. The aim of this study was to explore the cross-sectional and prospective mediating effects of dietary intake on the association of sedentary behaviour with BMI z-score (zBMI) in a cohort of Australian adolescents.

METHODS

Cross-sectional and prospective analyses were conducted in adolescents aged 12-15 years participating in the 2002/03 (baseline) and 2004/05 (follow-up) Nepean Growing Up Study. The independent variables were television (TV) viewing, an objective measure of total sedentary time and average sedentary bout duration, and the outcome variable zBMI. Using the Sobel-Goodman method with bootstrapping, mediation analyses were conducted examining three dietary components (discretionary foods, sugar-sweetened beverages [SSB] and takeaway foods) as mediators of associations between TV viewing and zBMI (n = 259) and between total sedentary time and average sedentary bout duration with zBMI (n = 140).

RESULTS

No significant cross-sectional or prospective total or direct associations were observed for TV viewing, total sedentary time and average sedentary bout duration with zBMI. However, TV viewing was positively associated with consumption of takeaway foods cross-sectionally (β = 0.06; 95% CI 0.01 to 0.12), prospectively at baseline (β = 0.07; 95% CI 0.01 to 0.12) and prospectively at follow-up (β = 0.10; 95% CI 0.04, 0.16), and average sedentary bout duration was inversely associated with SSB consumption both cross-sectionally (β = -0.36; 95% CI -0.69 to -0.02) and prospectively at baseline (β = -0.36; 95% CI -0.70 to -0.02). No mediation effects were identified.

CONCLUSIONS

TV viewing, total sedentary time and bouts of sedentary time were not associated cross-sectionally or prospectively with adolescents' zBMI, and three elements of dietary intake (e.g. intake of discretionary foods, SSB and takeaway foods) did not mediate this relationship. The role of dietary intake and sedentary behaviour in relation to adolescent health requires further clarification.

Physical Activity, Sedentary Time, and Fatness in a Biethnic Sample of Young Children

PURPOSE

This study aimed to investigate associations of objectively measured physical activity (PA) and sedentary time with adiposity in a predominantly biethnic (South Asian and White British) sample of young children.

METHODS

The sample included 333 children age 11 months to 5 yr who provided 526 cross-sectional observations for PA and body composition. Total PA volume (vector magnitude counts per minute), daily time at multiple intensity levels (the cumulative time in activity >500, >1000, >1500, …, >6000 counts per minute), and time spent sedentary (<820 counts per minute), in light PA (820-3907 counts per minute) and in moderate-to-vigorous PA (≥3908 counts per minute) were estimated with triaxial accelerometry. Indicators of adiposity included body mass index, waist circumference, and the sum of subscapular and triceps skinfold thicknesses. Statistical analyses were performed using multilevel regression and isotemporal substitution models adjusted for confounders. Effect modification by ethnicity was examined.

RESULTS

There was no evidence for effect modification by ethnicity (P interaction ≥ 0.13). In the whole sample, the accumulated time spent above 3500 counts per minute (i.e., high light-intensity PA) was inversely associated with the sum of skinfolds (β = -0.60 mm, 95% confidence interval [CI] = -1.19 to -0.021, per 20 min·d), and the magnitude of association increased dose dependently with PA intensity (peaking for time spent >6000 counts per minute = -1.57 mm, 95% CI = -3.01 to -0.12, per 20 min·d). The substitution of 20 min·d of sedentary time with moderate-to-vigorous PA was associated with a lower sum of skinfolds (-0.77 mm, 95% CI = -1.46 to -0.084).

CONCLUSIONS

High light-intensity PA appears to be beneficial for body composition in young South Asian and White British children, but higher-intensity PA is more advantageous.

Objectively measured sedentary time among five ethnic groups in Amsterdam: The HELIUS study

INTRODUCTION

Sedentary behaviour is increasingly recognised as a health risk. While differences in this behaviour might help explain ethnic differences in disease profiles, studies on sedentary behaviour in ethnic minorities are scarce. The aim of this study was to compare the levels and the socio-demographic and lifestyle-related correlates of objectively measured sedentary time among five ethnic groups in Amsterdam, the Netherlands.

METHODS

Data were collected as part of the HELIUS study. The sample consisted of adults from a Dutch, Moroccan, African Surinamese, South-Asian Surinamese and Turkish ethnic origin. Data were collected by questionnaire, physical examination, and a combined heart rate and accelerometry monitor (Actiheart). Sedentary time was defined as waking time spent on activities of <1.5 metabolic equivalents. Ethnic differences in the levels of sedentary time were tested using ANOVA and ANCOVA analyses, while ethnic differences in the correlates of sedentary time were tested with interactions between ethnicity and potential correlates using general linear models. Associations between these correlates and sedentary time were explored using linear regression analyses stratified by ethnicity (pre-determined). All analyses were adjusted for gender and age.

RESULTS

447 participants were included in the analyses, ranging from 73 to 109 participants per ethnic group. Adjusted levels of sedentary time ranged from 569 minutes/day (9.5 hours/day) for participants with a Moroccan and Turkish origin to 621 minutes/day (10.3 hours/day) in African Surinamese participants. There were no statistically significant differences in the levels or correlates of sedentary time between the ethnic groups. Meeting the physical activity recommendations (150 minutes/week) was consistently inversely associated with sedentary time across all ethnic groups, while age was positively associated with sedentary time in most groups.

CONCLUSIONS

No statistically significant differences in the levels of objectively measured sedentary time or its socio-demographic and lifestyle-related correlates were observed among five ethnic groups in Amsterdam, the Netherlands.

Cross-Sectional Associations of Objectively-Measured Physical Activity and Sedentary Time with Body Composition and Cardiorespiratory Fitness in Mid-Childhood: The PANIC Study

BACKGROUND

The minimum intensity of physical activity (PA) that is associated with favourable body composition and cardiorespiratory fitness (CRF) remains unknown.

OBJECTIVE

To investigate cross-sectional associations of PA and sedentary time (ST) with body composition and CRF in mid-childhood.

METHODS

PA, ST, body composition and CRF were measured in a population-based sample of 410 children (aged 7.6 ± 0.4 years). Combined heart-rate and movement sensing provided estimates of PA energy expenditure (PAEE, kJ/kg/day) and time (min/day) at multiple fine-grained metabolic equivalent (MET) levels, which were also collapsed to ST and light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Fat mass index (FMI, kg/m2), trunk fat mass index (TFMI, kg/m2) and fat-free mass index (FFMI, kg/m2.5) were derived from dual-energy X-ray absorptiometry. Maximal workload from a cycle ergometer test provided a measure of CRF (W/kg FFM). Linear regression and isotemporal substitution models were used to investigate associations.

RESULTS

The cumulative time above 2 METs (221 J/min/kg) was inversely associated with FMI and TFMI in both sexes (p < 0.001) whereas time spent above 3 METs was positively associated with CRF (p ≤ 0.002); CRF increased and adiposity decreased dose-dependently with increasing MET levels. ST was positively associated with FMI and TFMI (p < 0.001) but there were inverse associations between all PA categories (including LPA) and adiposity (p ≤ 0.002); the magnitude of these associations depended on the activity being displaced in isotemporal substitution models but were consistently stronger for VPA. PAEE, MPA and to a greater extent VPA, were all positively related to CRF (p ≤ 0.001).

CONCLUSIONS

PA exceeding 2 METs is associated with lower adiposity in mid-childhood, whereas PA of 3 METs is required to benefit CRF. VPA was most beneficial for fitness and fatness, from a time-for-time perspective, but displacing any lower-for-higher intensity may be an important first-order public health strategy. Clinical trial registry number (website): NCT01803776 ( https://clinicaltrials.gov/ct2/show/NCT01803776 ).

Inadequate Sleep as a Mediating Variable between Exposure to Interparental Violence and Depression Severity in Adolescents

Exposure to violence, including interparental and peer dating violence, is a public health concern associated with negative outcomes, including depression. However, little is known about mechanisms by which exposure to violence influences depressive symptoms. One factor that may help explain this association is problematic sleep. This study sought to determine whether short sleep duration mediates the relationship between exposure to violence (interparental and peer dating violence) and depressive symptoms. Structural equation modeling was used to examine the mediating role of short sleep duration from a 3-year longitudinal study of 1,042 high school students. Results demonstrated interparental violence was negatively related to sleep duration (friends dating violence was not), and sleep duration negatively associated with depressive symptoms. Adolescents exposed to violence between their parents obtained less sleep on school nights. In turn, they reported more depressive symptoms. Short sleep duration mediated the relationship between exposure to interparental violence and depression severity.

Physical activity, sedentary behavior, and long-term cardiovascular risk in young people: A review and discussion of methodology in prospective studies

The long-term effects of physical activity (PA) or sedentary behavior on cardiovascular health in young people are not well understood. In this study, we use a narrative format to review the evidence for a prospective association with adiposity and other well-established biological cardiovascular risk factors in healthy young people, considering only studies with at least 2 years of follow-up. PA appears to elicit a long-term beneficial effect on adiposity and particularly markers of cardiovascular health. With adiposity, however, a few studies also reported that higher levels of PA were associated with higher levels of adiposity. Time spent sedentary does not appear to be related to adiposity or markers of cardiovascular health independent of PA. We then discuss the uncertainties in the underlying causal chain and consider a number of alternative modeling strategies, which could improve our understanding of the relationship in future studies. Finally, we consider the current methodology for assessing PA and sedentary time.

Association between sleep duration and obesity is age- and gender-dependent in Chinese urban children aged 6-18 years: a cross-sectional study

Background

Information on the relationship between sleep duration and obesity among children in urban Guangzhou, China is limited. This study aims to examine the relationship between sleep duration and obesity in children aged 6–18 years.

Methods

The sample consisted of 11,830 children aged 6–18 years. The children were randomly selected from 13 schools in three urban districts of Guangzhou. The study was conducted from September to November 2013. The height and weight of the children were measured. Adiposity status was estimated using body mass index and according to the cut point in China criteria. In the structured questionnaire, children reported daily sleep hours (less than 7 h, 7–9 h and more than 9 h), weekly food intake amount (including vegetables, fruit, sugar beverages and meat), physical activity and sedentary time. A caretaker would answer the questionnaire on behalf of a child aged below nine.

Results

A total of 8,760 children (49.0 % boys) completed the study. The prevalence of obesity was 8.4 % (9.8 % in boys and 5.7 % in girls). Adjusted for age, diet and physical activity/sedentary behaviour, the odds ratio (OR) for obesity comparing sleeping <7 h (short sleep duration, SSD) with ≥9 h (long sleep duration, LSD) was 0.70 (95 % CI: 0.69–0.72) among boys and 1.73 (95 % CI: 1.71–1.74) among girls. Stratified by age, OR for boys aged 6–12 years comparing SSD with LSD was 0.60 (95 % CI: 0.55–0.66); by contrast, OR was 1.33 (95 % CI: 1.30–1.37) for boys aged 13–18 years.

Conclusion

Short sleep duration is associated with increased chances of obesity among girls and 13- to 18-year-old boys, but the chances of obesity are decreased among 6- to 12-year-old boys. Age and gender should be regarded as specific characteristics for the effects of short sleep on obesity.

Magnitude and determinants of change in objectively-measured physical activity, sedentary time and sleep duration from ages 15 to 17.5y in UK adolescents: the ROOTS study

Background

Self-reported physical activity (PA) and sleep duration (SLP) change markedly throughout adolescence. We sought to quantify changes in objectively-measured PA, sedentary time (ST) and SLP through adolescence, and to investigate baseline body composition and baseline activity levels as determinants of change.

Methods

Individually calibrated combined heart rate and movement sensing was used to estimate PA energy expenditure (PAEE), SLP, daily ST and time in light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous physical activity (MVPA) in 144 adolescents (50 % boys) of mean age 15.1(±0.3)y at baseline and 17.5(±0.3)y at follow-up. Changes in PA (ΔPA), ST (ΔST) and SLP (ΔSLP) were calculated as follow-up minus baseline values. Waist circumference (WC) was measured at baseline and follow-up, as was fat mass index (FMI) and fat-free mass index (FFMI) by a pooled estimation method including bio-impedance. Comparison of baseline and follow-up activity was made by mixed-model ANOVA. Linear regression adjusted for baseline demographics, total and weekend hours of monitor wear time and the seasons of activity measurements, was used to investigate baseline body composition as determinants of ΔPA, ΔST and ΔSLP. A further model adjusted for baseline of the outcome assessed baseline activity as a predictor of behaviour change, and investigated associations for baseline body composition independent of the baseline level of the outcome.

Results

From baseline to follow-up levels of MPA and VPA declined (p ≤ 0.039). The annual decline in MVPA was equivalent to -4.5 and -3.0 min/d in boys and girls, respectively. Baseline FMI, FFMI and WC were positively associated with ΔLPA and negatively associated with ΔST in boys when adjusted for baseline of the outcome (p ≤ 0.037 for all). SLP increased from baseline to follow-up (p = 0.004) but ΔSLP was not associated with baseline body composition (p ≥ 0.13). For all variables, higher baseline levels were associated with greater declines over time (p ≤ 0.003).

Conclusions

Levels of higher-intensity PA decline from mid-to-late adolescence, whereas the duration of sleep increases. Changes in LPA and ST may be associated with baseline body composition, but the baseline level of the outcome is consistently the strongest predictor of changes in adolescent activity.