Longitudinal Analysis of Sleep Duration and Cardiometabolic Risk in Young Children

Sleep duration is associated with metabolic syndrome in adolescents and children: a systematic review and meta-analysis

STUDY OBJECTIVES

Studies on the associations between sleep duration and metabolic syndrome in adolescents and children have reported mixed results. To shed more light on this issue, we conducted this meta-analysis by synthesizing the results of previous studies.

METHODS

Studies were retrieved from PubMed, Ovid, Cochrane, and Embase from inception to October 2021. Fixed-effects models and random-effects models were used to analyze the effects of sleep time on metabolic syndrome in adolescents.

RESULTS

Data from 7 studies, including 13,305 adolescents and children, were meta-analyzed. Compared with the control group, short sleep durations were not associated with a high prevalence of metabolic syndrome in adolescents and children using a random-effects model (odds ratio = 0.92, 95% confidence interval = 0.48-1.37, I2 = 56.5%, P = .378). Using a fixed-effects model on long sleep duration, this association was statistically significant (odds ratio = 0.57, 95% confidence interval = 0.38-0.76, I2 = 0.0%, P < .001) as a protective factor compared with shorter sleep duration.

CONCLUSIONS

Long sleep duration, instead of short sleep duration, was significantly associated with a lower prevalence of metabolic syndrome among adolescents and children.

CITATION

Xu Y, Hua J, Wang J, Shen Y. Sleep duration is associated with metabolic syndrome in adolescents and children: a systematic review and meta-analysis. J Clin Sleep Med. 2023;19(10):1835-1843.

Associations Between Meeting the 24-Hour Movement Guidelines and Cardiometabolic Risk in Young Children

INTRODUCTION

The authors aimed to examine the association between meeting the integrative movement behavior guidelines (physical activity, screen viewing, and sleep) and cardiometabolic risk (CMR) factors in young children.

METHODS

In this cross-sectional study, physical activity, screen viewing, and sleep were assessed using parent-reported data. The 24-Hour Movement Guidelines for the Early Years (0-4 y) were defined as 180 minutes of physical activity/day (of which ≥60 min should be moderate-to-vigorous intensity), ≤1 hour of screen viewing/day, and 10 to 13 hours of sleep/night. Waist circumference, glucose, high-density lipoprotein cholesterol, triglycerides, and systolic blood pressure were measured in a clinical setting by trained staff. A total CMR score and individual CMR factors served as primary and secondary outcomes, respectively.

RESULTS

Of the 767 participants (3-4 y), 26.4% met none of the guideline's recommendations, whereas 41.3%, 33.1%, and 10.6% of the sample met 1, 2, or all 3 recommendations, respectively. The number of recommendations met was not associated with the total CMR score or individual CMR factors (P > .05), with the exceptions of high-density lipoprotein (odds ratio = 1.61; 95% confidence interval, 1.11 to 2.33; P = .01).

CONCLUSION

Meeting the 24-Hour Movement Guidelines in early childhood was not associated with overall CMR, but was associated with favorable cholesterol outcomes.

Evaluation of body mass index and related lifestyle factors among 14-17-year-old Turkish adolescents

OBJECTIVE:

During adolescence, unhealthy body weight status is considered as a global concern as it may lead to adverse health consequences in adulthood, therefore evaluation of the risk factors is crucial. The aim of the study was to determine the prevalence of adolescents under the risk of being underweight, overweight, and obese among 14–17-year-old Turkish adolescents. In addition, we examined the association between unhealthy body weight categories and lifestyle factors.

METHODS:

This study was designed as cross-sectional study which included body weight status and associated parameters of 1561 adolescents aged between 14 and 17 who were registered 25 different high schools in Istanbul, Uskudar. Height and body weight of participants were measured and related factors were obtained through a questionnaire. Differences in distributions were analyzed using the Chi-square test and to control confounding factors, multivariate logistic regression analysis was performed. As statistical significance limit of p<0.05 was determined.

RESULTS:

Body mass index (BMI) percentile analyses indicated that 3.6% of participants were underweight, 14.3% were overweight, and 13.8% were obese. We demonstrated that age, gender, and school types were statistically very significantly associated with BMI (p<0.001) and daily meal frequency, eating speed, and mealtime regularity were significantly related with BMI (p<0.05). In addition, according to multivariate analysis results, gender and school types were closely related with obesity among 14–17-year old Turkish adolescents.

CONCLUSION:

This study has been demonstrated that frequency of adolescent obesity in Istanbul, Turkey, has increased and obesity closely related to gender and type of school. Further educational and interventional studies should be organized in this region with consideration of relevant risk factors.

Association of screen time and cardiometabolic risk in school-aged children

Screen use has become a pervasive behaviour among children and has been linked to adverse health outcomes. The objective of this study was to examine the association between screen time and a comprehensive total cardiometabolic risk (CMR) score in school-aged children (7-12-years), as well as individual CMR factors. In this longitudinal study, screen time was measured over time (average duration of follow-up was 17.4 months) via parent-report. Anthropometric measurements, blood pressure, and biospecimens were collected over time and used to calculate CMR score [sum of age and sex standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein cholesterol (HDL-c)/square-root of 5]. Generalized estimating equations (GEE) were used to examine the association between screen time and total CMR score as well as individual CMR factors. A total of 567 children with repeated measures were included. There was no evidence of an association between parent-reported child screen time and total CMR score (adjusted β = -0.01, 95% CI [-0.03, 0.005], 0.16). Screen time was inversely associated HDL-c (adjusted β = -0.008, 95% CI [-0.011, -0.005], p = 0.016), but there was no evidence that the other CMR components were associated with screen time. Among children 7-12 years, there was no evidence of an association between parent-reported child screen time and total CMR, but increased screen time was associated with slightly lower HDL-c. Research is needed to understand screen-related contextual factors which may be related to CMR factors.

Association of Physical Activity and Cardiometabolic Risk in Children 3-12 Years

BACKGROUND

This study aimed to examine the association between physical activity (PA) and a total cardio metabolic risk (CMR) score in children aged 3-12 years. Secondary objectives were to examine the association between PA and individual CMR factors.

METHODS

A longitudinal study with repeated measures was conducted with participants from a large primary care practice-based research network in Toronto, Canada. Mixed effects models were used to examine the relationship between parent-reported physical activity and outcome variables (total CMR score, triglycerides, glucose, high-density lipoprotein cholesterol, systolic blood pressure, waist circumference, weight-to-height ratio, and non-high-density lipoprotein cholesterol).

RESULTS

Data from 1885 children (6.06 y, 54.4% male) with multiple visits (n = 2670) were included in the analyses. For every unit increase of 60 minutes of PA, there was no evidence of an association with total CMR score (adjusted: -0.02 [-0.014 to 0.004], P = .11]. For the individual CMR components, there was evidence of a weak association between PA and systolic blood pressure (-0.01 [-0.03 to -0.01], P < .001) and waist-to-height ratio (-0.81 [-1.62 to -0.003], P < .001).

CONCLUSION

Parent-reported PA among children aged 3-12 years was not statistically associated with total CMR, but was weakly associated with systolic blood pressure and waist-to-height ratio.

The association between body mass index trajectories and cardiometabolic risk in young children

BACKGROUND

Rapid growth is associated with increased cardiometabolic risk (CMR) in adolescence and adulthood. Little is known about whether the association between rapid growth and increased CMR originates in early childhood.

OBJECTIVES

To identify age and sex standardized body mass index (zBMI) trajectories and to examine the association between zBMI trajectories and CMR outcomes in children 0 to 60 months.

STUDY DESIGN

A longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) in Toronto, Canada. Participants had repeated measures of weight and length or height performed from birth to 60 months of age. Latent class mixed modelling was used to identify the zBMI trajectories. Linear regressions were performed to determine the association between zBMI trajectories and the primary outcome, a CMR score, quantified as the sum of age- and sex- standardized waist circumference, systolic blood pressure, glucose, log-triglycerides and negative high-density lipoprotein cholesterol (HDL-C), divided by √5. Secondary outcomes were the individual components of the CMR formula as well as diastolic blood pressure and non-HDL-C.

RESULTS

Four BMI trajectories were identified among the 1166 children. After adjusting for all covariates, children in the rapidly accelerating trajectory had increased total CMR score (β = 1.38, 95% CI 0.77; 1.99, P < .001) and increased waist circumference score (β = 2.39, 95% CI 1.92; 2.86, P < .001) compared to the stable low group.

CONCLUSIONS

Rapid growth during early childhood is associated with increased CMR in preschool children, largely driven by larger waist circumference.

The association between screen time and cardiometabolic risk in young children

OBJECTIVES

While studies exist on the association between screen time and cardiometabolic risk among adolescents, research examining the effect of screen time on cardiometabolic risk in young children is lacking. The primary objective of this study was to examine the association between daily screen time and cardiometabolic risk (CMR) [sum of age- and sex-standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein (HDL) cholesterol divided by the square root of five] in young children. Secondary objectives included examining individual CMR risk factors, including waist-to-height ratio and non high-density lipoprotein (non-HDL) cholesterol, as well as the individual cut-offs of these risk factors. Additional analyses include examining the association between screen time and CMR by handheld/non-handheld devices.

METHODS

A study was conducted among young children 3 to 6 years from the TARGet Kids! practice-based research network in Toronto and Montreal, Canada. Children with one or more measures of screen time and CMR were included in this study. Generalized estimating equation (GEE) multivariable linear regressions and multivariable logistic regressions, using published cut-offs, were conducted to evaluate these associations.

RESULTS

Data from 1317 children [mean age 52 months (SD = 13.36), 44.34% female] were included for analyses. There was no evidence of associations between screen time and total CMR score or individual risk factors (p > 0.05) after adjusting for confounders. A statistically significant, but small association between daily screen time and non-HDL cholesterol was found (B = 0.046; CI = [0.017 to 0.075]; p = 0.002.

CONCLUSIONS

Though no relationship was reported between daily screen time and the majority of CMR factors in early childhood, there was an association between daily screen time and non-HDL cholesterol. As the relationship between daily screen time and CMR factors may not be apparent in early childhood, studies to evaluate longer-term cardiometabolic effects of screen time are needed. Although there is an evidence-based rationale to reduce screen time in early childhood, prevention of cardiometabolic risk may not be the primary driver.

Longitudinal Assessment of Sleep Trajectories during Early Childhood and Their Association with Obesity

Introduction: To identify longitudinal sleep trajectories in early childhood and examine the influence of sleep duration on obesity risk via BMI percentile (BMIp). Methods: Sleep, physical activity, and television viewing were measured in a cohort of 301 children, starting in 2001-2002, when children were 3 years and followed them through age 6. Nighttime sleep, daytime naps, and sleep duration were calculated. A series of latent growth curve models were used to estimate predictors of rate of change in sleep duration and BMIp overtime. A parallel process latent growth model examined the longitudinal relationship between sleep duration and BMIp simultaneously. Results: Most children (>80%) slept >10 hours per night across ages 3 to 6 years, despite the majority of children (>66%) having bedtimes after 9 pm. Sleep duration decreased on average by 0.22 (95% CI 0.20-0.24) hours each year of age (p < 0.001), while BMIp increased on average by 1.76 (95% CI 1.18-2.34) each year of age (p < 0.001). Baseline sleep duration predicted the BMIp slope factor, over and above strong effects of baseline BMIp. This indicated that greater sleep duration at baseline was predictive of decreased BMIp over time (unstandardized coefficient = -1.52 (95% CI 0.34-2.71, p = 0.012). Conclusions: Longer sleep duration at age 3 predicted decreased BMIp from ages 3 to 6. These findings indicate that focusing on sleep behaviors in children before age 3 may be a priority for pediatric providers with a goal of decreasing obesity risk.

Impact of lifestyle behaviors in early childhood on obesity and cardiometabolic risk in children: Results from the Spanish INMA birth cohort study

BACKGROUND

Identifying modifiable lifestyle behaviors linked to childhood obesity is necessary to develop preventive strategies.

OBJECTIVE

To estimate the association of five lifestyle behaviors in children aged 4 years on obesity and cardiometabolic risk factors at age 4 years and on obesity and blood pressure at age 7 years.

METHODS

We used child lifestyle data from the INMA project at age 4 years (n = 1480). We constructed a child lifestyle score by summing five behaviors (physical activity, sleep time, television time, plant based foods and intake of ultra-processed foods) and we categorized it into tertiles. At ages 4 and 7 years, we calculated age- and sex-specific z-scores for BMI, waist circumference (WC), and blood pressure. At age 4, we also calculated age-, and sex-, specific z-scores for triglycerides and HDL. We used linear and logistic regression analyses.

RESULTS

The lifestyle score was not associated with the outcomes at 4 years, but it was negatively associated with BMI and WC z-scores at age 7 years. Children at age 4 years in the highest tertile of the score had lower risk of overweight or obesity at age 7 years (OR = 0.61; 95% CI 0.39; 0.96) and abdominal obesity (OR = 0.48; 95% CI 0.24; 0.96).

CONCLUSIONS

Higher adherence to a healthy lifestyle at age 4 years decreased risk of overweight, obesity and abdominal obesity at 7 years.

Fit for School Study protocol: early child growth, health behaviours, nutrition, cardiometabolic risk and developmental determinants of a child's school readiness, a prospective cohort

INTRODUCTION

School readiness is a multidimensional construct that includes cognitive, behavioural and emotional aspects of a child's development. School readiness is strongly associated with a child's future school success and well-being. The Early Development Instrument (EDI) is a reliable and valid teacher-completed tool for assessing school readiness in children at kindergarten age. A substantial knowledge gap exists in understanding how early child growth, health behaviours, nutrition, cardiometabolic risk and development impact school readiness. The primary objective was to determine if growth patterns, measured by body mass index trajectories in healthy children aged 0-5 years, are associated with school readiness at ages 4-6 years (kindergarten age). Secondary objectives were to determine if other health trajectories, including health behaviours, nutrition, cardiometabolic risk and development, are associated with school readiness at ages 4-6 years. This paper presents the Fit for School Study protocol.

METHODS AND ANALYSIS

This is an ongoing prospective cohort study. Parents of children enrolled in the The Applied Health Research Group for Kids (TARGet Kids!) practice-based research network are invited to participate in the Fit for School Study. Child growth, health behaviours, nutrition, cardiometabolic risk and development data are collected annually at health supervision visits and linked to EDI data collected by schools. The primary and secondary analyses will use a two-stage process: (1) latent class growth models will be used to first determine trajectory groups, and (2) generalised linear mixed models will be used to examine the relationship between exposures and EDI results.

ETHICS AND DISSEMINATION

The research ethics boards at The Hospital for Sick Children, Unity Health Toronto and McMaster University approved this study, and research ethics approval was obtained from each school board with a student participating in the study. The findings will be presented locally, nationally and internationally and will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT01869530.

Cross-cultural disparities of subjective sleep parameters and their age-related trends over the first three years of human life: A systematic review and meta-analysis

Changes in nighttime sleep consolidation and daytime discontinuation have been observed in early life. Yet information about societal or cultural factors remains scant for implementing sleep recommendations. We aimed to provide pooled estimates of subjective sleep duration, number of nightwakings and sleep timing; to describe their age-related trends; and to determine potential cross-cultural disparities between predominantly-Asian (PA) and predominantly-Caucasian (PC) regions during the first three years of life. We performed this review according to the PRISMA guidelines. Overall, 102 studies with 167,886 children aged 0-3 y from 26 different countries/regions were included. Compared to PC regions, PA toddlers had shorter sleep duration and more frequent nightwakings. When PC regions were further divided into Pacific Rim and Europe, differences were much more evident between PA and Pacific Rim for all nighttime sleep parameters. Trends of nighttime sleep duration and bedtime for PC regions showed rapid changes over the first 3-6 mo before stabilizing to a plateau, whereas a different change was found for PA regions. In conclusion, an apparent cross-cultural disparity of the subjective sleep parameters already exists in early childhood. Improved operationalization of sleep parameters and more objective evidence are needed to establish cultural-sensitive recommendations this early in life.

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.

Associations of Infant Sleep Duration with Body Composition and Cardiovascular Health to Mid-Adolescence: The PEAS Kids Growth Study

Background: Short sleep duration in childhood has often been linked with obesity in later childhood or adolescence. However, whether infant sleep duration affects body composition trajectories and cardiovascular health through to mid-adolescence remains unknown. Methods: Participants were 336 adolescents from a community-based prospective birth cohort in Melbourne, Australia. Mothers completed 24-hour time diaries, including infant sleep in 5-minute intervals at ages 2, 4, and 12 months. BMI and body composition outcomes were measured 6-monthly between 4 and 6.5 years and at 10 and 14 years. Cardiovascular outcomes at 14 years comprised blood pressure, pulse wave velocity, retinal arteriole-to-venule ratio, and carotid intima-media thickness. We used multivariable linear regression and multinomial logistic regression analyses adjusted for sex, age, BMI at birth, gestational age, ethnicity, maternal education, maternal BMI, and neighborhood socioeconomic position. Results: At 2 months, infants slept on average 14.1 hours [standard deviation (SD) 1.9], decreasing to 13.4 hours (SD 2.0) by 12 months. We observed no associations between the different sleep duration time points in infancy and later BMI or body composition. Moreover, a shorter sleep duration did not increase the odds of being on a high body composition trajectory compared with longer sleep (e.g., odds ratio per hour of sleep at 4 months is 0.85, 95% confidence interval 0.65-1.11). Infant sleep duration was also not associated with cardiovascular function or large or small artery structure at 14 years of age. Conclusions: We found no evidence that sleep duration very early in life affects adolescent body composition or cardiovascular health.

Objective sleep and physical activity using 24-hour ankle-worn accelerometry among toddlers from low-income families

OBJECTIVES

Poverty is a risk for short sleep duration and limited physical activity. This study describes sleep, physical activity, and sedentary behavior of Women, Infants, and Children-eligible toddlers and the proportion of toddlers meeting recommendations for sleep and physical activity, and examines associations with body mass index z scores and poverty.

PARTICIPANTS/MEASUREMENTS

A total of 101 toddlers (12-32 months) from low-income families (62% African American) wore 24-hour ankle accelerometers over 3-7 consecutive days. Concurrent validity for daytime napping was assessed using parent-reported toddler wake/sleep between 08:00 and 20:00 collected using Ecological Momentary Assessment. Logistic regressions predicted odds of meeting guidelines.

RESULTS

Toddlers averaged 10.56 hours of sleep in 24 hours. All toddlers averaged ≥180 minutes of total activity per day, 38% had ≥60 minutes of moderate/vigorous physical activity per day, 32% of toddlers slept between 11 and 14 hours over 24 hours, and 26% had a bedtime before 9:00 pm. Body mass index z score was not associated with meeting guidelines. Poverty was associated with less than 60 minutes of moderate/vigorous physical activity.

CONCLUSIONS

Most toddlers were not meeting sleep guidelines. This study provides objective data on sleep and activity among a diverse sample of low-income toddlers. Objective measures of sleep and physical activity facilitate surveillance of children meeting guidelines for sleep and physical activity. Such norms are needed to examine disparities among children from varying racial and economic backgrounds. Future research should examine if meeting guidelines is related to other health indicators.

Temporal changes in obesity and sleep habits in Hong Kong Chinese school children: a prospective study

We examined the temporal changes in obesity and sleep habits and their relationship in a prospective cohort of healthy Chinese adolescents. We collected data on anthropometric and questionnaire-measured sleep parameters in 2007-2008. 516 participants returned for examinations in 2013-2015. General obesity was defined as body mass index (BMI) ≥age- and sex-specific 95th percentile or ≥25 kg/m2 for participants aged <18 or ≥18 years, respectively. Central obesity was defined as waist circumference (WC) ≥ age- and sex-specific 90th percentile or using adult cut-offs. After a mean follow-up of 6.2 ± 0.5 years, the mean BMI increased from 18.5 ± 3.1 to 20.9 ± 3.4 kg/m2. The corresponding WC were 63.7 ± 8.9 and 69.8 ± 9.7 cm. General obesity rate increased from 8.3% (95% confidence interval [CI] 6.1-11.1) to 11.3% (8.7-14.4; p = 0.034). Central obesity rate decreased from 16.9% (13.7-20.4) to 13.5% (10.6-16.8; p = 0.034). During follow-up, more participants reported short sleep (<7 hours/day during weekday: 20.5% [17.1-24.2] vs. 15.3% [12.3-18.8]; p = 0.033) and bedtime after midnight (60.5% [56.2-64.8] vs. 16.2% [13.1-19.7]; p < 0.001) than baseline. The relative risk of overweight/obesity in participants with short sleep and late bedtime was 1.30 (0.48-3.47) and 1.46 (0.70-3.05), respectively. Despite rising rates of unhealthy sleep habits and general obesity, their associations were not significant at 6-year of follow-up.

Association of sleep duration with metabolic syndrome and its components in children and adolescents; a propensity score-matched analysis: the CASPIAN-V study

OBJECTIVE

This study aims to evaluate the association of sleep duration with metabolic syndrome (MetS) and its components in a pediatric population.

METHODS

This multi-centric cross-sectional study was conducted in 2015 in 30 provinces of Iran. Participants consisted of 4200 school students aged 7-18 years, studied in a national school-based surveillance program (CASPIAN-V). Physical examinations and laboratory tests were performed using standard protocols. The analysis was conducted based on the propensity score matching and conditional logistic regression was used to evaluate the association of short sleep (less than 8 h a day) and the onset of sleep with MetS and its components. Results of conditional logistic regression was reported as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Overall, 3843 of participants completed the survey (response rate: 91.5%). Their mean (SD) age was 12.3 (3.2) years and 50.6% were boys. In the multivariate model, individuals who slept less than 8 h a day had significantly higher odds of MetS (OR 2.05, 95% CI 1.19-3.63) and high blood pressure (BP) (OR 1.46, 95% CI 1.04-2.06). Association between short sleep duration with other MetS components (including abdominal obesity, hypertriglyceridemia, hyperglycemia, and low levels of high-density lipoprotein-cholesterol was not statistically significant (P > 0.05). Moreover, association between the onset of sleep with MetS and its components was not statistically significant (P > 0.05).

CONCLUSION

Short sleep duration is associated with increased risk of MetS and high BP in children and adolescents. The clinical impact of current findings should be assessed in future longitudinal studies.

Sleep Duration and Obesity in Children and Adolescents

Increased rates of obesity internationally have drawn significant attention. In particular, researchers and practitioners are seeking new information about risk factors for obesity that could be areas for preventive interventions. Given that obesity rates in children and adolescents are increasing worldwide, particular attention to child and adolescent obesity is needed. A large, and growing, body of research indicates that inadequate sleep duration is linked to obesity. The current article reviews the extant literature concerning sleep duration and obesity in children and adolescents by reviewing current theories of obesity as well as available literature specifically evaluating the relationship of obesity and sleep in children and adolescents, including epidemiologic, experimental and intervention research. Overall, our literature review concludes that the relationship between shortened sleep and increased risk for obesity has research support internationally, including in the few Canadian articles available that are discussed in our review.

A Systematic Review of Sleep, Hypertension, and Cardiovascular Risk in Children and Adolescents

PURPOSE OF REVIEW

Many of the risk factors for heart disease have recently been shown to develop during childhood such as left ventricular hypertrophy and fibrous plaque lesions. As risk for cardiovascular disease in children and adolescents has risen, sleep duration has decreased, and inadequate sleep in children and adolescents has been found to be associated with cardiovascular disease risk. The aims of this manuscript are to provide an updated systematic review of the literature assessing sleep, hypertension, and cardiovascular risk and evaluate the strength of the evidence based on the available research.

RECENT FINDINGS

A systematic review was conducted using six databases from January 1, 2015 through March 9, 2018. We sought studies which looked at the relationship between sleep duration, sleep timing, or sleep quality and outcome variables of hypertension, inflammation, obesity, glucose or insulin, and lipids in children and adolescents. We found 24 studies which met our criteria. Nine studies included hypertension as an outcome variable; fifteen included obesity; thirteen included glucose or insulin; eight included lipids; and three included measures of inflammation. The existing literature on sleep and cardiovascular disease in children and adolescents is limited and relatively weak. Only one RCT was identified, and the overwhelming majority of studies had a high risk of bias. The strongest evidence of an association with sleep is with obesity, hypertension, and insulin sensitivity. Further research using more standardized methods and objective measures is needed to determine if a causal relationship truly exists between sleep and cardiovascular risk.

Association Between Sleep Duration and Body Mass Index Among US Low-Income Preschoolers

OBJECTIVE

To verify whether sleep duration was related to body mass index z scores (zBMI) and whether bedtimes or ethnicity was a moderator of the sleep duration-zBMI association among preschoolers from low-income families.

METHODS

Two hundred twenty-eight African American and Hispanic parents and their preschoolers were recruited from Head Start Centers. Parents reported their preschoolers' sleep duration and bedtimes (using the Children's Sleep Habits Questionnaire) and their television watching. Food intake was measured using multiple days of digital photography to estimate energy intake at dinner. The Parenting Stress Index and the Center for Epidemiologic Studies Depression Scale were used to measure stress and depression. Parents' and preschoolers' height and weight were measured by trained staff.

RESULTS

Longer sleep duration was significantly associated with lower zBMI when controlling for demographics, bedtimes, energy intake at dinner, and television watching, but not when also controlling for parents' demographics, BMI, stress, and depression. Preschoolers' sleep duration-zBMI association was not moderated by bedtimes or ethnicity.

CONCLUSIONS

Longer sleep duration was associated with lower zBMI among low-income preschoolers when controlling for preschoolers' characteristics, but this was no longer the case when also controlling for parents' characteristics. Additional studies are needed on the moderators of the sleep duration-zBMI association among low-income preschoolers.