Sleep duration and body-weight development during puberty in a Dutch children cohort

Sleep duration is associated with liver steatosis in children depending on body adiposity

Sleep is a factor associated with overweight/obesity risk, wherein interactions with fatty liver should be ascertained. The aim of this cross-sectional study was to analyze the possible relationships of sleep with liver health and whether this interplay is related to body adiposity distribution in children and adolescents. Anthropometric, clinical, and biochemical measurements were performed in children and adolescents (2-18 years old) with overweight/obesity (n = 854). Body fat distribution was clinically assessed, and several hepatic markers, including hepatic steatosis index, were calculated. Sleep time mediation (hours/day) in the relationship between the hepatic steatosis index and body fat distribution was investigated. Differences among diverse fatty liver disease scores were found between children with overweight or obesity (p < 0.05). Linear regression models showed associations between hepatic steatosis index and lifestyle markers (p < 0.001). Hepatic steatosis index was higher (about + 15%) in children with obesity compared to overweight (p < 0.001). Pear-shaped body fat distribution may seemingly play a more detrimental role on liver fat deposition. The association between sleep time and hepatic steatosis index was dependent on body mass index z-score. Post hoc analyses showed that 39% of the relationship of body fat distribution on hepatic steatosis index may be explained by sleep time.  Conclusion: An association of sleep time in the relationship between body fat distribution and hepatic steatosis index was observed in children and adolescents with overweight/obesity, which can be relevant in the prevention and treatment of excessive adiposity between 2 and 18 years old.

CLINICAL TRIAL

NCT04805762.    Import: As part of a healthy lifestyle, sleep duration might be a modifiable factor in the management of fatty liver disease in children.

WHAT IS KNOWN

• Sleep is an influential factor of overweight and obesity in children. • Excessive adiposity is associated with liver status in children and adolescents.

WHAT IS NEW

• Sleep time plays a role in the relationship between body fat distribution and liver disease. • Monitoring sleep pattern may be beneficial in the treatment of hepatic steatosis in children with excessive body weight.

Artificial neural network-based model for sleep quality prediction for frontline medical staff during major medical assistance

Background: The sleep quality of medical staff was severely affected during COVID-19, but the factors influencing the sleep quality of frontline staff involved in medical assistance remained unclear, and screening tools for their sleep quality were lacking. Methods: From June 25 to July 14, 2022, we conducted an Internet-based cross-sectional survey. The Pittsburgh Sleep Quality Index (PSQI), a self-designed general information questionnaire, and a questionnaire regarding the factors influencing sleep quality were combined to understand the sleep quality of frontline medical staff in Fujian Province supporting Shanghai in the past month. A chi-square test was used to compare participant characteristics, and multivariate unconditional logistic regression analysis was used to determine the predictors of sleep quality. Stratified sampling was used to divide the data into a training test set (n = 1061, 80%) and an independent validation set (n = 265, 20%). Six models were developed and validated using logistic regression, artificial neural network, gradient augmented tree, random forest, naive Bayes, and model decision tree. Results: A total of 1326 frontline medical staff were included in this survey, with a mean PSQI score of 11.354 ± 4.051. The prevalence of poor sleep quality was 80.8% (n = 1072, PSQI >7). Six variables related to sleep quality were used as parameters in the prediction model, including type of work, professional job title, work shift, weight change, tea consumption during assistance, and basic diseases. The artificial neural network (ANN) model produced the best overall performance with area under the curve, accuracy, sensitivity, specificity, precision, F1 score, and kappa of 71.6%, 68.7%, 66.7%, 69.2%, 34.0%, 45.0%, and 26.2% respectively. Conclusions: In this study, the ANN model, which demonstrated excellent predictive efficiency, showed potential for application in monitoring the sleep quality of medical staff and provide some scientific guidance suggestions for early intervention.

Objective and subjective sleep health in adolescence: Associations with puberty and affect

Sleep health tends to worsen during adolescence, partially due to pubertal-related changes that, in combination with social and psychological factors, can lead to long-lasting impairments in sleep health and affective functioning. Discrepant findings between subjective and objective measures of sleep in relation to affect have been reported in studies of adults; however, few investigations have assessed both subjective and objective sleep quality in a single sample, and fewer have examined this in the context of pubertal development. We aimed to (1) characterise pubertal associations with subjective sleep satisfaction, objective sleep efficiency, and objective and subjective sleep duration in adolescents; (2) examine the longitudinal association between daily affect and sleep metrics; and (3) test whether pubertal stage moderated this association. Eighty-nine participants (64% female, ages 13-20) completed an ecological momentary assessment (EMA) and actigraphy protocol. Independent of age, advanced pubertal stage was associated with lower subjective sleep satisfaction but not with objective sleep indices. Subjective sleep satisfaction was associated with within-person trajectories of negative affect, but not with positive affect. Pubertal stage and sleep satisfaction did not interact to predict within-day negative or positive affect. These findings are consistent with previous reports showing that objective and subjective sleep health are associated differently with puberty, and that subjective sleep health is associated with daily affect. Pubertal stage may be a more important indicator of subjective sleep quality in adolescence than is chronological age, most likely due to hormonal changes and psychological adjustment to the physical changes associated with the pubertal transition.

Changes in Sleep Patterns in Korean Early Adolescents during Sexual Maturation

Purpose: Teenagers’ sleep patterns show physiological delays influenced by sexual maturation and other external time-related factors. However, Korean adolescents show differences in the onset of pubertal development and have shorter sleep durations than other adolescents worldwide. Therefore, we assessed sleep patterns and sexual maturation in Korean early adolescents to evaluate changes in sleep patterns in relation to sexual maturation in early adolescents with sleep deprivation.Methods: From March to August 2017, we surveyed children aged 10 to 12 years in Seongnam (Seongnam Atopy Project). We evaluated items related to sleep and sexual maturation, assessed sleep duration and sleepiness scale scores, and analyzed the relationships of sleep parameters with sex, height, weight, and sexual maturation rating (SMR).Results: In total, 620 children were included. Sleep duration was 8.63±0.81 hours in boys and 8.40±0.98 hours in girls. Sleep started from PM 11:00±AM 0:47 in boys and PM 11:13±AM 1:06 in girls, and ended at AM 7:38±AM 0:27 in boys and AM 7:34±AM 0:27 in girls. After adjusting for sex and standardized body mass index, bedtime was delayed as the SMR increased (mean delay for each rating increase, 0.251 hours; P=0.001; 95% confidence interval [CI], 0.105 to 0.397). SMR did not influence the wake-up time, although sleep duration decreased as the SMR increased (mean decrease for each rating increase, 0.258 hours; P=0.001; 95% CI, –0.403 to –0.114). The sleepiness scale scores showed no relationship with SMR. Conclusion: Sleep patterns, especially sleep duration and bedtimes, show changes with sexual maturation in adolescents, who are vulnerable to sleep deprivation.

Sleep duration and obesity in children: A systematic review and meta-analysis of prospective cohort studies

AIM

Childhood obesity is a major public problem worldwide, and sleep duration may be associated with childhood obesity. We conducted a systematic review and meta-analysis of prospective cohort studies to estimate the associations between sleep duration and obesity/body mass index (BMI) in children.

METHODS

PubMed, Embase and the Cochrane Library were searched. For the meta-analysis, the pooled relative risk (RR) and 95% confidence intervals (CI) were estimated to reveal the association between short sleep duration and obesity. For the review, the outcomes focused on BMI change or subsequent BMI status.

RESULTS

A total of 12 studies (15 populations) met the criteria for inclusion in the meta-analysis. Short sleep duration was significantly associated with obesity (RR: 1.45; 95% CI: 1.14-1.85). After excluding two cohorts that substantially affected the heterogeneity, the pooled results remained significant (RR: 1.30; 95% CI: 1.20-1.42), and the association was not substantially altered in the subgroup analysis. In addition, we summarised 24 studies that met the criteria for our review of the relationship between sleeping and BMI.

CONCLUSION

The present meta-analysis indicated that short sleep duration increased the risk of childhood obesity. Public health efforts that encourage children to have sufficient sleep time may be important in combating obesity.

Is sleep education an effective tool for sleep improvement and minimizing metabolic disturbance and obesity in adolescents?

The prevalence of childhood obesity has increased significantly in recent years. Obesity is associated with a range of adverse physiological, psychological and social outcomes and places a huge economical burden on healthcare systems around the world. Insufficient sleep duration is common in adolescents and exacerbated by contemporary lifestyles, but may be a contributor to obesity onset and metabolic disruption. We briefly review the current evidence surrounding the associations between sleep and obesity as well as diabetes. Sleep improvement programs have been suggested as a potential avenue to raise awareness of the importance of sleep and ultimately enhance sleep behaviors/routines. A review of the current literature supporting the efficacy of such programs is tentative. Furthermore, very few studies have investigated if sleep enhancement has downstream positive effects on metabolic function or body weight in adolescents. We highlight biological and social factors that intensify sleep loss in adolescents and recommend that these be targeted components in future interventions aimed at improving adolescent sleep.

Ethnic differences in sleep duration at 5 years, and its relationship with overweight and blood pressure

BACKGROUND

Studies on adult population indicate shorter sleep duration in ethnic minority groups than host populations. We examined ethnic differences in sleep duration and its relationship with overweight and blood pressure (BP) among children living in Amsterdam.

METHODS

Participants include 2384 children (aged 5 years) and their mothers from the Amsterdam-based longitudinal study. Sleep was categorised into short sleep (<10 h/night) and normal sleep (10-11 h/night). Linear regressions ( Β: were used to study association between sleep duration and systolic BP (SBP) and diastolic BP (DBP). Prevalence ratios (PRs) were used to study ethnic differences in sleep duration and its association with overweight and raised BP.

RESULTS

Minority groups reported shorter sleep duration compared to native Dutch, with prevalence ranging from 11.3% in Dutch to 53.1% in Ghanaians. Age-adjusted PRs ranged from 3.38 (95%CI 2.63-4.34) in Moroccans to 4.78 (95%CI 3.36-6.82) in Ghanaian compared with Dutch children. Increased prevalence of overweight was observed among children with short sleep in Dutch and Moroccans only, but this risk was no longer statistically significant after further adjustment for socioeconomic status. Short sleep was not related to SBP and DBP in all groups. No relationship was observed between short sleep and raised BP except for African Surinamese (3.65, 95% CI 1.23-10.8).

CONCLUSION

Like adults, children from ethnic minority populations sleep less hours than Dutch children. Efforts to improve ethnic inequalities in sleep hygiene should also include children at younger age. Associations as reported in adults with overweight and BP could not consistently be replicated in children, however.

Sleep, circadian rhythm and body weight: parallel developments

Circadian alignment is crucial for body-weight management, and for metabolic health. In this context, circadian alignment consists of alignment of sleep, meal patterns and physical activity. During puberty a significant reduction in sleep duration occurs, and pubertal status is inversely associated with sleep duration. A consistent inverse association between habitual sleep duration and body-weight development occurs, independent of possible confounders. Research on misalignment reveals that circadian misalignment affects sleep-architecture and subsequently disturbs glucose–insulin metabolism, substrate oxidation, leptin- and ghrelin concentrations, appetite, food reward, hypothalamic–pituitary–adrenal-axis activity and gut-peptide concentrations enhancing positive energy balance and metabolic disturbance. Not only aligning meals and sleep in a circadian way is crucial, also regular physical activity during the day strongly promotes the stability and amplitude of circadian rhythm, and thus may serve as an instrument to restore poor circadian rhythms. Endogenicity may play a role in interaction of these environmental variables with a genetic predisposition. In conclusion, notwithstanding the separate favourable effects of sufficient daily physical activity, regular meal patterns, sufficient sleep duration and quality sleep on energy balance, the overall effect of the amplitude and stability of the circadian rhythm, perhaps including genetic predisposition, may integrate the separate effects in an additive way.

Sleep efficiency as a determinant of insulin sensitivity in overweight and obese adolescents

Insulin resistance (IR) occurs in a transient manner during puberty. Obese adolescents may be at risk for persistent IR during puberty. The objective of the study is to review the literature on the association of the anthropometry and lifestyle characteristics with insulin sensitivity in overweight and obese adolescents, and include data from a new study. Relevant papers were selected and reviewed. In addition, 137 overweight and obese adolescents (42 male/95 female, age 14.4 ± 2.3 years, BMI z-score +3.3 ± 0.7, HOMA-IR 3.4 ± 1.8) from the Centre for Overweight Adolescent and Children's Healthcare (MUMC+) were included in this study. Anthropometrics, Tanner stages, sleep characteristics, food intake behaviour and physical activity were determined, and possible associations with homeostasis model assessment of insulin resistance (HOMA-IR) were tested.

RESULTS

Overweight and obese adolescents with unfavourable fat partitioning and family history of NIDDM are at risk for persistent IR. Overweight and obese adolescents from the new cohort showed a higher HOMA-IR postpubertally. BMI z-score, age, pubertal stage and prepubertally total sleeping time (TST) and sleep efficiency (SE) were identified as significant contributors. Overweight and obese adolescents showed a persistently higher instead of transiently higher HOMA-IR during puberty, associated with BMI z-score, age, pubertal stage and prepubertally less TST and SE.

Sleep duration differences between children of migrant and native origins

Aim

To explore whether primary school children of migrant and native Dutch origins differ regarding their sleep duration per night, a risk for overweight and obesity, and to determine to what degree differences in parenting styles contribute to these differences.

Subjects and methods

A cross-sectional survey, including 1,943 children aged 8-9 years old and their primary caregivers, was performed. Data were collected from primary schools in cities and adjacent municipalities in The Netherlands: Eindhoven and Rotterdam. The outcome measure was mean sleep duration per night. The main independent variable was migrant background, based on the country of birth of the parents. A possible mediating variable was parenting style (rejecting, neglecting, permissive, authoritarian, authoritative). Age and sex of the child as well as parental socioeconomic status, as indicated by educational level, were added as confounders.

Results

Dutch children have the highest sleep duration: more than 11 h (mean = 670.1; SD = 27.7). All migrant children show less than 11 h of sleep per night. Migrant children of non-Western origin, especially Turkish and Moroccan children, show the lowest sleep duration per night. Parenting styles do not contribute to these differences.

Conclusion

Migrant background is associated with sleep duration. As children of migrant origin are, in general, at higher risk for overweight and obesity and sleep duration is regarded as a risk factor for overweight and obesity, further investigation of this association is needed.

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

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We examined sedentary time and sleep length relative to changes in youth adiposity.

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Sedentary time was not associated with change in adiposity in either gender.

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Sleep duration was significantly inversely associated with adiposity gain in boys.

•

The association for sleep in boys was attenuated by physical activity and depression.

Objective

The objective of this study was to investigate whether objectively measured sedentary time and sleep duration are associated with changes in adiposity from mid- to late adolescence.

Methods

Students (n = 504, 42% boys) were recruited from schools in Cambridgeshire, UK. At baseline (mean age 15.0 ± 0.3 years), sedentary time was objectively measured by ≥3 days of combined heart rate and movement sensing. Concurrently, sleep duration was measured by combined sensing in conjunction with self-reported bed times. Fat mass index (FMI; kg/m²) was estimated at baseline and follow-up (17.5 ± 0.3 years) by anthropometry and bioelectrical impedance. FMI change (ΔFMI) was calculated by subtracting the baseline from follow-up values. Linear regression models adjusted for basic demographics, moderate-to-vigorous physical activity (MVPA), and depressive symptoms were used to investigate associations of sedentary time and sleep duration (mutually adjusted for one another) with ΔFMI.

Results

FMI increased by 0.5 and 0.6 kg/m² in boys and girls, respectively, but there was no association between sedentary time and ΔFMI in either gender (p ≥ 0.087), and no association between sleep duration and ΔFMI in girls (p ≥ 0.61). In boys, each additional hour of baseline sleep significantly reduced the ΔFMI by 0.13 kg/m² (p = 0.049), but there was little evidence for this association after adjusting for MVPA and depressive symptoms (p = 0.15).

Conclusions

Sedentary time may not determine changes in adiposity from mid- to late adolescence, nor may sleep duration in girls. However, sleep length may be inversely associated with adiposity gain in boys, depending on whether the relationship is confounded or mediated by MVPA and depression.

Does Short Sleep Lead to Obesity Among Children and Adolescents? Current Understanding and Implications

Childhood obesity continues to be a major public health concern in the United States. This work reviews the current understanding of the relationship between sleep duration and obesity among children and adolescents. A systematic search was conducted for papers published between January 2000 and July 2013 using keywords: (sleep) and (overweight or obesity or obese or body mass index or BMI or adiposity or body fat or fat) and (children or child or youth or teen or pediatric or adolescent or paediatric or childhood or adolescence or boy or girl). Reference lists of relevant articles and reviews or meta-analysis articles were checked to identify additional studies. Only empirical work and longitudinal studies that focused on children and adolescents were included in this review. The search identified 22 longitudinal studies. The majority of the reviewed studies support the presence of an inverse relationship between sleep duration and obesity. However, in some studies the relationship was not significant in adjusted analyses. Differences as a function of age and gender were also noted. Despite more than a decade of research, the debate on the association between sleep duration and obesity continues. Further research with repeated assessments, valid objective measures, and better control of potential confounding variables is warranted.

Television viewing, bedroom television, and sleep duration from infancy to mid-childhood

BACKGROUND

Television and insufficient sleep are associated with poor mental and physical health. This study assessed associations of TV viewing and bedroom TV with sleep duration from infancy to midchildhood.

METHOD

We studied 1864 children in Project Viva. Parents reported children's average daily TV viewing and sleep (at 6 months and annually from 1-7 years) and the presence of a bedroom TV (annually 4-7 years). We used mixed effects models to assess associations of TV exposures with contemporaneous sleep, adjusting for child age, gender, race/ethnicity, maternal education, and income.

RESULTS

Six hundred forty-three children (35%) were racial/ethnic minorities; 37% of households had incomes ≤$70 000. From 6 months to 7 years, mean (SD) sleep duration decreased from 12.2 (2.0) hours to 9.8 (0.9) hours per day; TV viewing increased from 0.9 (1.2) hours to 1.6 (1.0) hours per day. At 4 years, 17% had a bedroom TV, rising to 23% at 7 years. Each 1 hour per day increase in lifetime TV viewing was associated with 7 minutes per day (95% confidence interval [CI]: 4 to 10) shorter sleep. The association of bedroom TV varied by race/ethnicity; bedroom TV was associated with 31 minutes per day shorter sleep (95% CI: 16 to 45) among racial/ethnic minority children, but not among white, non-Hispanic children (8 fewer minutes per day [95% CI: -19 to 2]).

CONCLUSIONS

More TV viewing, and, among racial/ethnic minority children, the presence of a bedroom TV, were associated with shorter sleep from infancy to midchildhood.

Depressive symptoms in adolescence: a poor indicator of increases in body mass index

PURPOSE

The purpose of this study was to examine the association between depressive symptoms and subsequent body mass index (BMI) z scores among early-to-mid adolescents, extending previous research by using objectively measured weight and height data.

METHODS

Latent growth curve analysis was used to examine whether growth parameters of zBMI could be predicted by depressive symptoms (n = 2,051 adolescents, 48.5% female, at baseline; 1,465 with data at all three time points). Specifically, we tested whether depressive symptoms were associated with the initial assessment of BMI (intercept) as well as with changes in BMI over time (slope). Analyses were performed for the total group, and separately for boys and girls.

RESULTS

Depressive symptoms were not associated with the slope of zBMI. In girls, but not boys, depressive symptoms were positively associated with the intercept of zBMI.

CONCLUSIONS

Findings suggest that although depressive symptoms among females are associated with a higher zBMI, they do not predict excessive weight gain during early-to-mid adolescence.

Familial risk moderates the association between sleep and zBMI in children

OBJECTIVE

A cumulative risk approach was used to examine the moderating effect of familial risk factors on relations between actigraphy-based sleep quantity (minutes) and quality (efficiency) and sex- and age-standardized body mass index (zBMI).

METHODS

The sample included 124 boys and 104 girls with a mean age of 10.41 years (SD = 0.67). Children wore actigraphs for 1 week, and their height and weight were assessed in the lab.

RESULTS

After controlling for potential confounds, multiple regression analyses indicated that sleep minutes predicted children's zBMI and that both sleep minutes and efficiency interacted with family risk in the prediction of zBMI. The association between poor sleep and zBMI was especially evident for children exposed to higher levels of family risk.

CONCLUSIONS

Findings suggest that not all children who exhibit poor sleep are at equal risk for higher zBMI and that familial and contextual conditions need to be considered in this link.

Obesity: lessons from evolution and the environment

The 9th Stock Conference acknowledged the complex background of genetic, cultural, environmental and evolutionary factors of obesity. Gene-environment interactions underlie the flexibility in body-weight and body-fat regulation, illustrated by the hunter-gatherers' feast and famine lifestyle, the variation in physical activity over the lifespan being highest at reproductive age, the variation in energy intake through 'eating in the absence of hunger', while running the risk of exceeding the capacity of triacylglyceride storage, leading to lipotoxicity and metabolic problems. Perinatal metabolic programming for obesity via epigenetic changes in response to a 'Western diet' results in production of lipid-poor milk and metabolically efficient pups, contributing to the perpetuation of obesity throughout generations. Evolutionary insight from comparative physiology and ecology indicates that over generations activity-induced energy expenditure has remained the same compared to wild mammals, that energy balance might be dependant on protein balance, while the function of taste changed from detection of poison or energy to social drinking and social behaviour. At present, the impact of assortative mating on obesity prevalence is unambiguously positive. The complexity that appeared can only be fully appreciated by setting the data into the context of our evolutionary history.

Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment

There are three mechanisms that may contribute to the health, performance, and safety problems associated with night-shift work: (1) circadian misalignment between the internal circadian clock and activities such as work, sleep, and eating, (2) chronic, partial sleep deprivation, and (3) melatonin suppression by light at night. The typical countermeasures, such as caffeine, naps, and melatonin (for its sleep-promoting effect), along with education about sleep and circadian rhythms, are the components of most fatigue risk-management plans. We contend that these, while better than nothing, are not enough because they do not address the underlying cause of the problems, which is circadian misalignment. We explain how to reset (phase-shift) the circadian clock to partially align with the night-work, day-sleep schedule, and thus reduce circadian misalignment while preserving sleep and functioning on days off. This involves controlling light and dark using outdoor light exposure, sunglasses, sleep in the dark, and a little bright light during night work. We present a diagram of a sleep-and-light schedule to reduce circadian misalignment in permanent night work, or a rotation between evenings and nights, and give practical advice on how to implement this type of plan.

The association between short sleep duration and weight gain is dependent on disinhibited eating behavior in adults

STUDY OBJECTIVE

To investigate whether the relationship between short sleep duration and subsequent body weight gain is influenced by disinhibited eating behavior.

DESIGN

Six-year longitudinal study.

SETTING

Community setting.

PARTICIPANTS

Two hundred seventy-six adults aged 21 to 64 years from the Quebec Family Study.

MEASUREMENTS AND RESULTS

Body composition measurements, self-reported sleep duration, and disinhibition eating behavior trait (Three-Factor Eating Questionnaire) were determined at both baseline and after 6 years. For each sleep-duration group (short- [≤6 h] average, [7-8 h], and long- [≥9 h] duration sleepers), differences in weight gain and waist circumference were tested by comparing the lowest (score ≤ 3) versus the highest (score ≥ 6) disinhibition eating behavior tertiles using analysis of covariance, with adjustment for potential confounding factors. Individuals having both short sleep duration and high disinhibition eating behavior were more likely to gain weight and increase their abdominal circumference over time (P<0.05); however, short-duration sleepers having a low disinhibition eating behavior trait were not more likely to increase their adiposity indicators than were average-duration sleepers. Over the 6-year follow-up period, the incidence of overweight/obesity for short-duration sleepers with a high disinhibition eating behavior trait was 2.5 times more frequent than for short-duration sleepers with a low disinhibition eating behavior trait. Energy intake was significantly higher in short-duration sleepers with a high disinhibition eating behavior trait (P<0.05 versus all other groups).

CONCLUSIONS

We observed that having a high disinhibition eating behavior trait significantly increased the risk of overeating and gaining weight in adults characterized by short sleep duration. This observation is novel and might explain the interindividual differences in weight gain associated with short sleep duration.

Shorter sleep may be a risk factor for impaired bone mass accrual in childhood

The purpose of the study was to investigate whether sleep duration during early childhood was associated with fat mass and bone mineral content (BMC). BMC and fat mass were measured by dual-energy X-ray absorptiometry in children (n=336) aged 4-12 yr. Sleep was quantified according to parental report of hours slept at night and napping. The relationship between sleep pattern and body composition was tested using analysis of variance including confounding factors. Based on the sample distribution, children were grouped into tertiles of sleep duration. BMC was greater in children with longer sleep duration (p=0.02). Age was inversely associated with sleep duration; therefore, the sample was analyzed by age category using age 7 yr as a cut-off point. The relationship remained significant only among younger children. Napping was positively associated with BMC (p=0.001). Sleep duration was not associated with fat parameters. Longer sleep duration may allow for optimal energy resource partitioning in which bone is favored. Sleep duration of less than 8h may impair bone mass accrual, particularly during periods of rapid growth.

Longitudinal associations between sleep duration and subsequent weight gain: a systematic review

OBJECTIVE

To systematically examine the relationship between sleep duration and subsequent weight gain in observational longitudinal human studies.

METHODS

Systematic review of twenty longitudinal studies published from 2004-October 31, 2010.

RESULTS

While adult studies (n = 13) reported inconsistent results on the relationship between sleep duration and subsequent weight gain, studies with children (n = 7) more consistently reported a positive relationship between short sleep duration and weight gain.

CONCLUSION

While shorter sleep duration consistently predicts subsequent weight gain in children, the relationship is not clear in adults. We discuss possible limitations of the current studies: 1) the diminishing association between short sleep duration on weight gain over time after transition to short sleep, 2) lack of inclusion of appropriate confounding, mediating, and moderating variables (i.e., sleep complaints and sedentary behavior), and 3) measurement issues.

Obesity and short sleep: unlikely bedfellows?

The link between habitual short sleep and obesity is critically examined from a sleep perspective. Sleep estimates are confounded by 'time in bed', naps; the normal distribution of sleep duration. Wide categorizations of 'short sleep', with claims that <7 h sleep is associated with obesity and morbidity, stem from generalizations from 5 h sleepers (<8% of adults) and acute restriction studies involving unendurable sleepiness. Statistically significant epidemiological findings are of questionable clinical concern, even for 5 h sleepers, as any weight gains accumulate slowly over years; easily redressed by e.g. short exercise exposures, contrasting with huge accumulations of 'lost' sleep. Little evidence supports 'more sleep', alone, as an effective treatment for obesity. Impaired sleep quality and quantity are surrogates for many physical and psychological disorders, as can be obesity. Advocating more sleep, in these respects, could invoke unwarranted use of sleep aids including hypnotics. Inadequate sleep in obese children is usually symptomatic of problems not overcome by increasing sleep alone. Interestingly, neuropeptides regulating interactions between sleep, locomotion and energy balance in normal weight individuals, are an avenue for investigation in some obese short sleepers. The real danger of inadequate sleep lies with excessive daytime sleepiness, not obesity.