Sleep duration, sleep–wake schedule regularity, and body weight in Hong Kong Chinese adolescents

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.

Characteristic Sleep Patterns and Associated Obesity in Adolescents

Poor sleep adversely affects health and may cause obesity. Poor sleep includes short sleep duration, low quality of sleep, and sleep discrepancy. Although most studies have focused on the association between sleep duration and obesity, poor sleep is a significant risk factor for obesity. Adolescents have characteristic sleep patterns which correspond to poor sleep. Adolescents sleep late due to various biological and psychosocial factors; also, they wake up early to be on time for school. This causes them to sleep less. To make up for this sleep debt, adolescents sleep more on non-school days, which causes sleep discrepancies. Therefore, since adolescents have characteristic sleep patterns, an in-depth investigation is needed to identify whether poor sleep is a risk for obesity. This article presents an overview of the characteristic sleep patterns of adolescents, and reviews studies on the association of each sleep pattern with obesity.

Sleep onset, duration, or regularity: which matters most for child adiposity outcomes?

BACKGROUND/OBJECTIVES

Sleep measures, such as duration and onset timing, are associated with adiposity outcomes among children. Recent research among adults has considered variability in sleep and wake onset times, with the Sleep Regularity Index (SRI) as a comprehensive metric to measure shifts in sleep and wake onset times between days. However, little research has examined regularity and adiposity outcomes among children. This study examined the associations of three sleep measures (i.e., sleep duration, sleep onset time, and SRI) with three measures of adiposity (i.e., body mass index [BMI], waist circumference, and waist-to-height ratio [WHtR]) in a pediatric sample.

SUBJECTS/METHODS

Children (ages 4-13 years) who were part of the U.S. Newborn Epigenetic STudy (NEST) participated. Children (N = 144) wore an ActiGraph for 1 week. Sleep measures were estimated from actigraphy data. Weight, height, and waist circumference were measured by trained researchers. BMI and WHtR was calculated with the objectively measured waist and height values. Multiple linear regression models examined associations between child sleep and adiposity outcomes, controlling for race/ethnicity, child sex, age, mothers' BMI and sleep duration.

RESULTS

When considering sleep onset timing and duration, along with demographic covariates, sleep onset timing was not significantly associated with any of the three adiposity measures, but a longer duration was significantly associated with a lower BMI Z-score (β = -0.29, p < 0.001), waist circumference (β = -0.31, p < 0.001), and WHtR (β = -0.38, p < 0.001). When considering SRI and duration, duration remained significantly associated with the adiposity measures. The SRI and adiposity associations were in the expected direction, but were non-significant, except the SRI and WHtR association (β = -0.16, p = 0.077) was marginally non-significant.

CONCLUSIONS

Sleep duration was consistently associated with adiposity measures in children 4-13 years of age. Pediatric sleep interventions should focus first on elongating nighttime sleep duration, and examine if this improves child adiposity outcomes.

Weekend night vs. school night sleep patterns, weight status, and weight-related behaviors among adolescents

OBJECTIVE

In this study, we examine associations between objectively measured weekend night vs. school night sleep patterns, weight status, and weight-related behaviors among adolescents.

DESIGN

Cross-sectional study.

SETTING

Five Minnesota high schools that started early (7:30 or 7:45 AM) in Spring 2016.

PARTICIPANTS

Ninth grade students, ages 14.5-16 years (n = 284).

MEASUREMENTS

Students completed surveys, had body measurements taken, and wore sleep (wrist) actigraphs for 1 week (n = 284). We examined weekend night-school night differences in sleep duration and sleep timing. We then assessed whether these factors were related to weight status and weight-related behaviors (eating behaviors, food consumption, physical activity, beverage consumption) using generalized linear mixed models.

RESULTS

On average, students slept 1.5 hours (95% confidence interval 1.3-1.7) more and had a sleep midpoint 1.9 hours (1.8-2.1) later on weekend nights compared to school nights. Female students had larger increases in sleep duration on weekend nights than males but similar timing differences. Sleep duration differences were uncorrelated with sleep timing differences (r = 0.01). Neither duration nor timing differences were associated with overweight, obesity, or any of the eating behaviors we examined. However, sleeping longer on weekend nights than on school nights was associated with lower probability of being active 6-7 days per week (p = .02).

CONCLUSIONS

Adolescents have substantial sleep duration and sleep timing differences on weekend nights vs. school nights. While these differences may not be associated with weight status or weight-related behaviors, they reflect the reality that most adolescents have schedules that restrict their sleep.

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.

Adolescent sleep characteristics and body-mass index in the Family Life, Activity, Sun, Health, and Eating (FLASHE) Study

Sleep may play a role in overweight and obesity in adolescents. The objective of this study is to investigate the relationships between sleep duration and timing and overweight and obesity status in adolescents, with a special emphasis on weekday-weekend difference in sleep characteristics as well as sex-specific relationships. We examined 1,254 U.S. adolescents (12-17 years) self-reported sleep duration, timing, weekday-weekend differences in duration and timing in relation to overweight and obesity. We found an inverse association between sleep duration and overweight and obesity. Compared to 8-9 h of sleep, short sleep (< 7 h) on weekdays was associated with higher odds of overweight and obesity [Odds ratio (95% confidence interval), 1.73 (1.00, 2.97)] in the overall population, while long sleep (10+ h) on weekends was associated with lower odds, but only in males [0.56 (0.34, 0.92)]. We also found that a larger weekday-weekend difference in sleep duration was associated with overweight and obesity in females, but not in males. Specifically, the odds of overweight and obesity were significantly higher among females reporting longer sleep on weekends than weekdays by ≥ 2 h [2.31 (1.15, 4.63)] when compared to those reporting little weekday-weekend differences. Sleep timing, or weekday-weekend differences in sleep timing, were not associated with overweight and obesity in the overall population, although we found suggestive evidence linking later weekend sleep with overweight and obesity in females. Our findings support a role of sleep in adolescent obesity and suggest sex-differences in this relationship that warrant future studies.

Associations between Sleep Pattern and Quality and Cardiovascular Risk Factors among Macao School Students

Background: Despite accumulating evidence showing that sleep duration and cardiometabolic health are correlated, the association of sleep regularity and quality with cardiovascular risk factors in children and adolescents remains inconclusive. Therefore, we examined the relationship between sleep regularity/quality and cardiovascular risk factors in children and adolescents in Macao, China. Methods: We conducted a cross-sectional study among primary and secondary school students (age range: 9-18 years) in Macao, China. Body weight, height, waist circumference (WC), and serum lipid levels were measured. Sleep regularity and sleep quality were assessed by using the Pittsburgh Sleep Quality Index. Multivariable logistic regression was conducted to examine the relationship of sleep variables with the increased likelihood of body mass index (BMI)-classified overweight/obesity, WC-classified obesity, and dyslipidemia. Results: A total of 1078 school students were included in the analysis. Differences of >2 hours between weekday and weekend bedtimes were associated with the increased risk of BMI-classified overweight/obesity (odds ratio = 2.58, 95% confidence interval = 1.55-4.31, p < 0.01) after being adjusted for sleep variables and lifestyle factors. No statistically significant association was found between poor sleep quality and any other outcome. Conclusions: Irregular bedtime was associated with elevated body weight regardless of sleep amount and quality. Thus, regular bedtimes are recommended as a simple but practical strategy for preventing obesity.

Development of sleep patterns in children with obese and normal-weight parents

AIM

To study the sleep development and sleep characteristics in children at different obesity risks, based on parental weight, and also to explore their weekday-weekend sleep variations and associated family factors.

METHODS

A total of 145 children participating in a longitudinal obesity prevention project were included, of which 37 had normal-weight parents (low obesity risk), and 108 had overweight/obese parents (high obesity risk). Sleep diaries at ages 1 and 2 years were used to study sleep development in children at different obesity risks. Objectively assessed sleep using an accelerometer at 2 years of age was used to analyse weekday-weekend sleep variations.

RESULTS

There was no difference in sleep development from age 1 to age 2 among children at different obesity risks, but more children in the high-risk group had prolonged sleep onset latency and low sleep efficiency. At 2 years of age, children in the high-risk group had more weekday-weekend variation in sleep offset (mean difference 18 min, 95% confidence interval (CI) 4-33 min), midpoint of sleep (mean difference 14 min, 95% CI 3-25 min) and nap onset (mean difference 42 min, 95% CI 10-74 min) than children in the low-risk group, after adjusting for other family factors. However, no difference could be detected between groups in weekday-weekend variation in sleep duration.

CONCLUSIONS

Unfavourable sleep characteristics, as well as more variation in sleep schedules, have been observed in children at high obesity risk. While the differences were relatively small, they may reflect the unfavourable sleep hygiene in families at high obesity risk.

Sleep Patterns and Quality Are Associated with Severity of Obesity and Weight-Related Behaviors in Adolescents with Overweight and Obesity

BACKGROUND

Inadequate sleep duration, sleep patterns, and sleep quality have been associated with metabolic, circadian, and behavioral changes that promote obesity. Adolescence is a period during which sleep habits change to include less sleep, later bedtimes, and greater bedtime shift (e.g., difference between weekend and weekday bedtime). Thus, sleep may play a role in adolescent obesity and weight-related behaviors. This study assesses sleep duration, quality, and schedules and their relationships to relative weight and body fat percentage as well as diet, physical activity, and screen time in adolescents with overweight/obesity.

METHODS

Adolescents between 12 and 17 years old (n = 186) were weighed and measured, reported typical sleep and wake times on weekdays and weekends, and responded to questionnaires assessing diet, physical activity, and screen time habits.

RESULTS

Controlling for sleep duration, later weekend bedtime and greater bedtime shift were associated with greater severity of overweight (β = 0.20; β = 0.16) and greater screen time use (β = 0.22; β = 0.2). Later bedtimes on the weekdays and weekends were associated with fewer healthy diet practices (β = -0.26; β = -0.27). In addition, poorer sleep quality was associated with fewer healthy diet habits (β = -0.21), greater unhealthy diet habits (β = 0.15), and less physical activity (β = -0.22). Sleep duration was not associated with any weight or weight-related behavior.

CONCLUSIONS

Sleep patterns and quality are associated with severity of overweight/obesity and various weight-related behaviors. Promoting a consistent sleep schedule throughout the week may be a worthwhile treatment target to optimize behavioral and weight outcomes in adolescent obesity treatment.

Prevalence of overweight in Hong Kong Chinese children: Its associations with family, early-life development and behaviors-related factors

Background

Childhood overweight is a crucial public health concern. Recognizing its associated factors can facilitate the establishment of effective prevention strategies. The aim of the present study was to examine the prevalence of overweight in Hong Kong Chinese children and explore its influential factors in relation to family, early-life development and behavior-related issues.

Methods

A cross-sectional study was conducted in 894 primary school students aged 9-12 years (50.4% boys). Self-reported information on family background (parental body weight, education, employment status, household income, living space, and bedroom situation), early-life developmental variables (birth weight, gestational age and feeding pattern), and children's lifestyle factors (sleep, various eating behaviors and physical activity) were collected with a questionnaire. A logistic regression was performed to test the associations.

Results

The overweight prevalence in Hong Kong children was 19.9%. Compared to the girls, the boys were more overweight (23.5% vs. 16.3%). Overweight was linked to paternal overweight, maternal overweight, lower maternal education, less monthly household income, and shorter sleep duration. Compared to the breast-fed children, those who were not breast-fed were more likely to become overweight, with marginal significance.

Conclusion

The present study revealed a high prevalence of overweight in Hong Kong pediatric population and demonstrated the family resemblance in weight status. Further interventions and promotions should involve parents and consider the family as a unit to tackle childhood overweight.

School-Based Sleep Education Programs for Short Sleep Duration in Adolescents: A Systematic Review and Meta-Analysis

BACKGROUND

Insufficient sleep among students is a major school health problem. School-based sleep education programs tailored to reach large number of students may be one of the solutions. A systematic review and meta-analysis was conducted to summarize the programs' effectiveness and current status.

METHODS

Electronic databases were searched up until May 2015. Randomized controlled trials of school-based sleep intervention among 10- to 19-year-old students with outcome on total sleep duration were included. Methodological quality of the studies was assessed using the Cochrane's risk of bias assessment.

RESULTS

Seven studies were included, involving 1876 students receiving sleep education programs and 2483 attending classes-as-usual. Four weekly 50-minute sleep education classes were most commonly provided. Methodological quality was only moderate, with a high or an uncertain risk of bias in several domains. Compared to classes-as-usual, sleep education programs produced significantly longer weekday and weekend total sleep time and better mood among students at immediate post-treatment, but the improvements were not maintained at follow-up.

CONCLUSIONS

Limited by the small number of studies and methodological limitations, the preliminary data showed that school-based sleep education programs produced short-term benefits. Future studies should explore integrating sleep education with delayed school start time or other more effective approaches.

Relationship of Sleep Duration and Regularity with Dietary Intake Among Preschool-Aged Children with Obesity from Low-Income Families

OBJECTIVE

Diet is a modifiable factor associated with pediatric obesity outcomes, but few studies have evaluated the relationships of sleep duration and regularity on dietary intake of young preschool-aged children. The goal of this study was to evaluate whether short sleep duration and irregular sleep timing were associated with greater calorie, carbohydrate and fat consumption among young children with obesity from low-income families.

METHODS

Fifty-one ethnically diverse children aged 2 to 4 years were recruited from the Special Supplemental Nutrition Program for Women, Infants, and Children clinics in a southeast Texas county. Sleep behaviors were parent reported using the Child Sleep Assessment tool. Dietary intake data were obtained by 24-hour recall interviews (2 weekdays and 1 weekend day).

RESULTS

Short sleep duration (<11 hr) was highly prevalent among this cohort of preschool-aged children. Short sleep duration was associated with greater fat and decreased carbohydrate consumption. Children with greater variability in sleep duration and timing had greater energy intake from fat and protein sources.

CONCLUSION

Allowing for the opportunity to educate parents on the importance of maintaining regular, adequate sleep and relationships between sleep and dietary intake may decrease the risk of childhood obesity in this high-risk pediatric population.

Sleep patterns and obesity in childhood

PURPOSE OF REVIEW

To highlight the recent findings on sleep-obesity associations in children. We focus on sleep duration, sleep timing and chronotype, and describe the potential mechanisms underlying sleep-obesity associations.

RECENT FINDINGS

Poor sleep is increasingly common in children and associations between short sleep duration in early childhood and obesity are consistently found. Less is known about the infancy period, and the findings in adolescents are inconsistent. Sleep timing patterns may also contribute to obesity risk. Variable and shifted sleep schedules and evening chronotypes have recently been linked to adiposity in adults; less is known about children. Further, there is little understanding regarding the mechanisms of association. The timing of eating, dietary intake, obesogenic eating behaviors, and changes in appetite-regulating hormones have been identified as possible mechanisms for sleep-obesity associations and may be promising avenues for future research. Longitudinal and experimental work with children is needed to determine the nature of associations.

SUMMARY

Beyond sleep duration, sleep timing patterns may contribute to obesity risk. Biological and behavioral processes have been proposed as mechanisms that may explain the association. Understanding the pathways through which poor sleep patterns could increase obesity risk in children may provide novel avenues for intervention.

Sleep duration, schedule and quality among urban Chinese children and adolescents: associations with routine after-school activities

Background

With rapid urbanization accompanied by lifestyle changes, children and adolescents living in metropolitan areas are faced with many time use choices that compete with sleep. This study reports on the sleep hygiene of urban Chinese school students, and investigates the relationship between habitual after-school activities and sleep duration, schedule and quality on a regular school day.

Methods

Cross-sectional, school-based survey of school children (Grades 4–8) living in Shanghai, China, conducted in 2011. Self-reported data were collected on students’ sleep duration and timing, sleep quality, habitual after-school activities (i.e. homework, leisure-time physical activity, recreational screen time and school commuting time), and potential correlates.

Results

Mean sleep duration of this sample (mean age: 11.5-years; 48.6% girls) was 9 hours. Nearly 30% of students reported daytime tiredness. On school nights, girls slept less (p<0.001) and went to bed later (p<0.001), a sex difference that was more pronounced in older students. Age by sex interactions were observed for both sleep duration (p=0.005) and bedtime (p=0.002). Prolonged time spent on homework and mobile phone playing was related to shorter sleep duration and later bedtime. Adjusting for all other factors, with each additional hour of mobile phone playing, the odds of daytime tiredness and having difficulty maintaining sleep increased by 30% and 27% among secondary students, respectively.

Conclusion

There are sex differences in sleep duration, schedule and quality. Habitual activities had small but significant associations with sleep hygiene outcomes especially among secondary school students. Intervention strategies such as limiting children’s use of electronic screen devices after school are implicated.

Sleep timing moderates the concurrent sleep duration-body mass index association in low-income preschool-age children

OBJECTIVE

To test the independent main and moderating effects of sleep timing on body mass index (BMI) in low-income preschool-age children (M = 4.11 years, SD = 0.54).

METHODS

Parents reported demographics and children's sleep concurrently, and a subset of children was followed longitudinally. Child height and weight were measured and BMI z score (BMIz) calculated. Regression analysis evaluated main effects of sleep timing (bedtime, weekday-to-weekend schedule shifting, napping) on concurrent BMIz and future rate of change, and their moderating effects on the sleep duration-BMIz association.

RESULTS

Of 366 children (longitudinal subsample = 273), 50% were boys, 57% white, and 37% overweight or obese. Nocturnal sleep duration predicted concurrent BMIz, but not rate of change in BMIz over time. Bedtime was a moderator; the sleep duration-BMIz association was present only among children with bedtimes after 9 pm (β = -0.44; 95% confidence interval -0.69, -0.18). Schedule shifting was a moderator; the association between greater nocturnal sleep duration and lesser rate of future BMIz increase was present only among children with the most consistent sleep schedules (<45-minute delay in weekend bedtime: β = -0.12; 95% confidence interval -0.23, -0.01). Daytime napping did not moderate the nocturnal sleep duration-BMIz association. Covariates (sleep-disordered breathing, soda consumption, home chaos) did not explain these associations.

CONCLUSIONS

Among low-income preschoolers, sleep timing moderated the nocturnal sleep duration-BMIz association. Understanding how sleep timing and sleep duration relate to childhood obesity is important for prevention efforts.