Adiposity in Adolescents: The Interplay of Sleep Duration and Sleep Variability

[Relationship between diet, nutritional aspects and sleep quality in a pediatric population]

Introduction

The relationship between diet and sleep has been studied in adults. However, there is little evidence in the pediatric population. The objective of this review was to analyze in a narrative way the relationship between diet, some nutritional aspects and sleep quality in population under 14 years. A quick review was performed in MEDLINE (PubMed) and Cochrane with a search strategy combining MeSH terms and keywords. Studies were selected to estimate diet and evaluate nutritional status and sleep in children using different tools. The risk of bias from the 14 selected studies was determined with validated tools (AMSTAR 2, Newcastle Ottawa scale [NOS] and Risk of Bias [Rob2]). Adherence to some dietary patterns such as the Mediterranean, high consumption of fruits and vegetables, tryptophan intake or substitution of saturated fatty acids by unsaturated fats were associated with better sleep quality. The consumption of ultra-processed products, the "unhealthy fast food" or the high intake of simple sugars hinder an adequate rest. On the other hand, an association between a high body mass index and lack of sleep was observed in young people under 14. In conclusion, the collected studies showed a significant association between some dietary patterns, food groups and nutrients with sleep quality. "Unhealthy" dietary factors were associated with poorer sleep quality. However, healthier and recommended habits and diets were associated with improved sleep hygiene. On the other hand, the lack of hours of rest in the youth population increases height, weight and BMI. Further research is needed in this direction.

The efficacy of sleep lifestyle interventions for the management of overweight or obesity in children: a systematic review and meta-analysis

BACKGROUND

Childhood obesity remains a significant public health concern. Sleep duration and quality among children and youth are suboptimal worldwide. Accumulating evidence suggests an association between inadequate sleep and obesity risk, yet it is unclear whether this relationship is causal. This systematic review examines the efficacy of sleep interventions alone or as a part of lifestyle interventions for the management of overweight or obesity among children and adolescents.

METHODS

A keyword/reference search was performed twice, in January 2021 and May 2022 in MEDLINE/PubMed, EMBASE/Ovid, PsycINFO/EBSCO, The Cochrane Library, Web of Science Core Collection/Web of Science, SciELO/Web of Science, and CINAHL/EBSCO. Study eligibility criteria included youth with overweight or obesity between 5 and 17, were RCTs or quasi-randomized, and focused on the treatment of overweight and obesity with a sleep behavior intervention component. Risk of bias was assessed using the Cochrane Risk of Bias assessment tool (RoB2). A Meta-analysis was conducted to estimate the effect of interventions with a sleep component on BMI. The study protocol was registered in PROSPERO (CRD42021233329).

RESULTS

A total of 8 studies (2 quasi-experiments, 6 RCTs) met inclusion criteria and accounted for 2,231 participants across 7 countries. Only one study design isolated the effect of sleep in the intervention and reported statistically significant decreases in weight and waist circumference compared to control, though we rated it at high risk of bias. Our meta-analysis showed no significant overall effect on children's BMI as a result of participation in an intervention with a sleep component (Cohen's d = 0.18, 95% CI= -0.04, 0.40, Z = 1.56, P = .11), though caution is warranted due to substantial heterogeneity observed across studies (Tau2 = 0.08; X2 = 23.05, df = 7; I2 = 83.73%).

CONCLUSIONS

There were mixed results on the effect of sleep interventions across included studies on BMI, other weight-related outcomes, diet, physical activity, and sleep. Except for one study at low risk of bias, three were rated as 'some concerns' and four 'high risk of bias'. Findings from this study highlight the need for additional RCTs isolating sleep as a component, focusing on children and adolescents living with overweight and obesity.

Disparities in sleep-wake patterns by labor force status: Population-based findings

Sleep disturbances have been associated with unemployment, but variation in sleep-wake patterns by labor force status has rarely been examined. With a population-based sample, we investigated differences in sleep-wake patterns by labor force status (employed, unemployed, and not-in-the-labor-force) and potential disparities by sociodemographic variables. The analysis included 130,602 adults aged 25-60 y, who participated in the American Time Use Survey between 2003 and 2019. Individual sleep-wake pattern was extracted from time use logs in a strict 24-h period (04:00 h-03:59 h). Functional nonparametric regression models based on dimensionality reduction and neighborhood matching were applied to model the relationship between sleep-wake patterns and labor force status. Specifically, we predicted changes in intra-person sleep-wake patterns under hypothetical changes of labor force status from employed to unemployed or not-in-the-labor-force. We then studied moderations of this association by gender, race/ethnicity and educational attainment. In comparison to the employed state, unemployed and not-in-the-labor-force states were predicted to have later wake-times, later bedtimes, and higher tendency for taking midday naps. Changes in labor force status led to more apparent shifts in wake-times than in bedtimes. Additionally, sleep schedules of Hispanics and those with higher education level were more vulnerable to the change of labor force status from employed to unemployed.

"I need to be alert at night to provide care": Factors associated with problematic sleep among young Australian caregivers

OBJECTIVES

There is increased recognition that young people (<25 years) may occupy a carer role for family or others with health conditions or disability. This is often in addition to study and social activities. This means competing demands on time, and insufficient sleep. Our aim was to determine the contribution of caring duties to problematic sleep in young carers.

METHODS

A survey of Australian carers was conducted, including questions on demographics, characteristics of the carer and care recipient, and sleep quality and quantity. Participants were eligible if they reported sleep time <7 hr or dissatisfaction with their sleep, and were aged 15-24 years.

RESULTS

A total of 110 participants (71.8%_female = 79, 15-17 years = 62, 18-24 years = 48) were included in analysis; 55.5% (n= 61) reporting dissatisfaction with their sleep and 62.7% (n= 69) reporting typically less than 7 hr sleep per night. Sleep duration was significantly shorter for those who reported 1-2 or ≥3 awakenings to provide care, compared with no awakenings (p_< .05). Sleep quality, as described by scores on the Pittsburgh Sleep Quality Index (PSQI) was also significantly worse for those who were frequently awoken by their care recipient (p < .05). Worrying about the care recipient, being woken by the care recipient, and listening out for the care recipient were the most frequently identified factors impacting on sleep.

CONCLUSION

Young carers experience reduced sleep duration and poor sleep quality. Strategies to alleviate the burden of care work on young carer's sleep would benefit the health and safety of this group.

Validation of the Entrainment Signal Regularity Index and associations with children's changes in BMI

OBJECTIVE

This study examined the validity of a novel metric of circadian health, the Entrainment Signal Regularity Index (ESRI), and its relationship to changes in BMI during the school year and summer.

METHODS

In a longitudinal observational data set, this study examined the relationship between ESRI score and children's (n = 119, 5- to 8-year-olds) sleep and physical activity levels during the school year and summer, differences in ESRI score during the school year and summer, and the association of ESRI score during the school year and summer with changes in BMI across those time periods.

RESULTS

The ESRI score was higher during the school year (0.70 ± 0.10) compared with summer (0.63 ± 0.11); t(111) = 5.484, p < 0.001. Whereas the ESRI score at the beginning of the school year did not significantly predict BMI change during the school year (β = 0.05 ± 0.09 SE, p = 0.57), having a higher ESRI score during summer predicted smaller increases in BMI during summer (β = -0.22 ± 0.10 SE, p = 0.03).

CONCLUSIONS

Overall, children demonstrated higher entrainment regularity during the school year compared with the summer. During summer, having a higher entrainment signal was associated with smaller changes in summertime BMI. This effect was independent of the effects of children's sleep midpoint, sleep regularity, and physical activity on children's BMI.

Sleep variability and regularity as contributors to obesity and cardiometabolic health in adolescence

OBJECTIVE

Adolescence is a developmental stage of critical changes in sleep and its circadian timing when the contribution of abnormal sleep variability (amount) and sleep regularity (timing) to obesity and its associated adverse cardiometabolic health outcomes appears to increase. The aim of this study was to summarize findings from studies conducted in adolescents examining both sleep variability and regularity in relation to obesity and cardiometabolic health. Gaps in research and potential causal pathways that future studies should examine are highlighted.

RESULTS

Nightly deviations in sleep duration and sleep midpoint appear to contribute to the development of obesity and associated adverse cardiometabolic outcomes in youth. Studies show that increased sleep variability and irregularity are associated with obesity, decreased physical activity, dysregulated eating and inadequate diet, metabolic dysfunction, impaired cardiac autonomic balance, and elevated blood pressure in adolescents.

CONCLUSIONS

A stable circadian timing of sleep is essential to the overall physical well-being of youth. Emerging evidence supports that sleep variability and circadian misalignment, including sleep irregularity, contribute to adverse obesity-related health outcomes early on in adolescence. Future studies should focus on the underlying behavioral and biological mechanisms in the causal pathway between day-to-day deviations in the amount and timing of sleep and obesity.

Childhood diabetes and sleep

Sleep modulates glucose metabolism, both in healthy states and in disease. Alterations in sleep duration (insufficient and excessive) and obstructive sleep apnea may have reciprocal ties with obesity, insulin resistance and Type 2 diabetes, as demonstrated by emerging evidence in children and adolescents. Type 1 diabetes is also associated with sleep disturbances due to the influence of wide glycemic fluctuations upon sleep architecture, the need to treat nocturnal hypoglycemia, and the need for glucose monitoring and insulin delivery technologies. In this article, we provide an extensive and critical review on published pediatric literature regarding these topics, reviewing both epidemiologic and qualitative data, and provide an overview of the pathophysiology linking sleep with disorders of glucose homeostasis.

The roles of sleep and executive function in adolescent nighttime eating

Nighttime eating has been associated with obesity, inflammation, and poor nutritional intake, yet correlates of this behavior are understudied in pediatric populations and among adolescents in particular. The current study examines modifiable factors related to nighttime eating, including sleep parameters and regulatory abilities-as well as the interplay between these constructs-in adolescents. A total of 223 adolescents (Mage = 15.32 years, 52.9 % female, 15.7 % classified as overweight, 21.1 % had obesity) wore ActiGraph devices to measure sleep and were instructed to complete three 24-h dietary recall measures over a two-week period. Participants also completed self-report measures of executive function. Greater variability in sleep duration was consistently associated with higher average calorie, sugar, and fat consumption after 8, 9, and 10 PM. The main effect of global executive function on all nighttime eating measures was nonsignificant, and executive function did not moderate relationships between sleep parameters and nighttime eating measures. Since adolescents' eating habits may set the stage for lifelong dietary practices, efforts to ensure consistent sleep duration may reduce risk for nighttime eating in this nutritionally vulnerable population.

Interplay of Environmental, Individual and Genetic Factors in Rheumatoid Arthritis Provocation

In this review, we explore systemization of knowledge about the triggering effects of non-genetic factors in pathogenic mechanisms that contribute to the development of rheumatoid arthritis (RA). Possible mechanisms involving environmental and individual factors in RA pathogenesis were analyzed, namely, infections, mental stress, sleep deprivation ecology, age, perinatal and gender factors, eating habits, obesity and smoking. The non-genetic factors modulate basic processes in the body with the impact of these factors being non-specific, but these common challenges may be decisive for advancement of the disease in the predisposed body at risk for RA. The provocation of this particular disease is associated with the presence of congenital loci minoris resistentia. The more frequent non-genetic factors form tangles of interdependent relationships and, thereby, several interdependent external factors hit one vulnerable basic process at once, either provoking or reinforcing each other. Understanding the specific mechanisms by which environmental and individual factors impact an individual under RA risk in the preclinical stages can contribute to early disease diagnosis and, if the factor is modifiable, might be useful for the prevention or delay of its development.

Third-Trimester Maternal Dietary Patterns Are Associated with Sleep Health among Adolescent Offspring in a Mexico City Cohort

BACKGROUND

Maternal diet during gestation has been linked to infant sleep; whether associations persist through adolescence is unknown.

OBJECTIVES

We explored associations between trimester-specific maternal diet patterns and measures of sleep health among adolescent offspring in a Mexico City birth cohort.

METHODS

Data from 310 mother-adolescent dyads were analyzed. Maternal diet patterns were identified by principal component analysis derived from FFQs collected during each trimester of pregnancy. Sleep duration, midpoint, and fragmentation were obtained from 7-d actigraphy data when adolescents were between 12 and 20 y old. Unstratified and sex-stratified association analyses were conducted using linear regression models, adjusted for potential confounders.

RESULTS

Mean ± SD age of offspring was 15.1 ± 1.9 y, and 52.3% of the sample was female. Three diet patterns were identified during each trimester of pregnancy: the Prudent Diet (PD), high in lean proteins and vegetables; the Transitioning Mexican Diet (TMD), high in westernized foods; and the High Meat & Fat Diet (HMFD), high in meats and fat products. Mean ± SD sleep duration was 8.5 ± 1.5 h/night. Most associations were found in the third trimester. Specifically, PD maternal adherence was associated with shorter sleep duration among offspring (-0.57 h; 95% CI: -0.98, -0.16 h, in the highest tertile compared with the lowest) and earlier sleep midpoint among females (-0.77 h; 95% CI: -1.3, -0.26 h). Adherence to the HMFD and TMD was nonlinearly associated with less fragmented sleep, with the latter only evident among females.

CONCLUSIONS

Findings indicate that maternal dietary patterns, especially during the third trimester of pregnancy, may have long-term impacts on offspring sleep.

Prenatal maternal pesticide exposure in relation to sleep health of offspring during adolescence

STUDY OBJECTIVES

The neurobiological processes involved in establishing sleep regulation are vulnerable to environmental exposures as early as seven weeks of gestation. Studies have linked in utero pesticide exposure to childhood sleep-disordered breathing. However, the impact of in utero pesticide exposure on the sleep health of adolescents remains unexplored.

MATERIALS AND METHODS

Data from 137 mother-adolescent pairs from a Mexico City cohort were analyzed. We used maternal urinary 3-phenoxybenzoic acid (3-PBA, pyrethroid metabolite) and 3, 5, 6-trichloro-2-pyridinol (TCPy, chlorpyrifos metabolite) from trimester three to estimate in utero pesticide exposure. Among adolescents, we obtained repeated measures of objectively assessed sleep duration, midpoint, and fragmentation using wrist-actigraphy devices for 7 consecutive days in 2015 and 2017. Unstratified and sex-stratified associations between maternal urinary 3-PBA and TCPy and adolescent sleep measures were examined using generalized linear mixed models (GLMMs). We also examined the interactive effects of maternal pesticide exposure and offspring sex on sleep outcomes.

RESULTS

3-PBA and TCPy were detected in 44.4% and 93% of urine samples, respectively. Adjusted findings demonstrated that higher exposure to maternal TCPy was associated with longer sleep duration and later sleep timing. Findings from interaction tests between maternal pesticide exposure and offspring sex were not statistically significant, although adjusted sex-stratified findings showed that the association between TCPy with duration and midpoint was evident only among female offspring. To illustrate, those in the highest tertile of exposure had a 59 minute (95% CI: 12.2, 104.8) (p, trend = 0.004) longer sleep duration and a 0.6 hour (95% CI: 0.01, 1.3) (p, trend = 0.01) later sleep midpoint. We found no significant associations between 3-PBA and sleep outcomes.

CONCLUSION

Within a cohort of mother-adolescent pairs, we found associations between maternal prenatal pesticide exposure and longer sleep duration and later sleep timing among adolescent offspring. Further, this association may be female-specific.

Multivariate Functional Kernel Machine Regression and Sparse Functional Feature Selection

Motivated by mobile devices that record data at a high frequency, we propose a new methodological framework for analyzing a semi-parametric regression model that allow us to study a nonlinear relationship between a scalar response and multiple functional predictors in the presence of scalar covariates. Utilizing functional principal component analysis (FPCA) and the least-squares kernel machine method (LSKM), we are able to substantially extend the framework of semi-parametric regression models of scalar responses on scalar predictors by allowing multiple functional predictors to enter the nonlinear model. Regularization is established for feature selection in the setting of reproducing kernel Hilbert spaces. Our method performs simultaneously model fitting and variable selection on functional features. For the implementation, we propose an effective algorithm to solve related optimization problems in that iterations take place between both linear mixed-effects models and a variable selection method (e.g., sparse group lasso). We show algorithmic convergence results and theoretical guarantees for the proposed methodology. We illustrate its performance through simulation experiments and an analysis of accelerometer data.

Burden of sleep disturbance in non-Hispanic Black pregnant women

STUDY OBJECTIVES

Non-Hispanic Black pregnant women disproportionately experience poor perinatal outcomes compared to other racial/ethnic groups. Sleep disruption has emerged as a risk factor for adverse pregnancy outcomes but there are limited data in minority pregnant women. We examined the prevalence of habitual snoring and its timing of onset with several key sleep-wake disturbances and their associations with perinatal outcomes in a cohort of non-Hispanic Black pregnant women.

METHODS

Third trimester non-Hispanic Black pregnant women were recruited from a large, academic medical center and screened for habitual snoring - and its timing relative to pregnancy - sleep quality, symptoms of insomnia, excessive daytime sleepiness, as well as daytime function. Clinical diagnoses of hypertensive disorders of pregnancy were obtained along with delivery outcomes.

RESULTS

In 235 women the vast majority (80%) reported three or more sleep-wake disturbances, and almost half had at least five disturbances. Sixteen percent endorsed pre-pregnancy snoring and 20% pregnancy-onset snoring. Women with pregnancy-onset snoring had significantly increased odds of poor sleep quality aOR 8.2, trouble staying asleep aOR 3.6, waking up too early aOR 2.7, excessive daytime sleepiness aOR 2.3, and poor daytime function aOR 8.7 but no relationship with perinatal outcomes. In contrast, pre-pregnancy snoring was related to chronic hypertension, pre-term delivery and fetal growth restriction; aOR 2.6, aOR 2.8, and aOR 5.1 respectively.

CONCLUSIONS

Sleep-wake disturbances confer a significant burden to pregnant non-Hispanic Black women, an infrequently studied yet disproportionately affected population. Contributions of maternal sleep to racial disparities in perinatal health should be a priority for public health research.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Associations between bedtime eating or drinking, sleep duration and wake after sleep onset: findings from the American time use survey

Sleep hygiene recommendations discourage eating before bedtime; however, the impact of mealtime on sleep has been inconsistent. We examined gender-stratified associations between eating or drinking <1, <2 and <3 h before bedtime, sleep duration and wake after sleep onset (WASO >30 min). This study utilised 2003-2018 data from the American Time Use Survey, a nationally representative sample of USA residents aged ≥15 years. Participants recorded weekday/weekend activities during a 24-h period. Age-specific sleep duration and WASO were estimated categorically and continuously. Eating or drinking were identified from all activities recorded <1, <2 and <3 h before bedtime. Mean ± se sleep duration was 8·0 ± 0·006 h, and 6% of participants ate or drank <1 h prior to weekdays bedtime. Overall, eating or drinking <1 h prior to bedtime was associated with longer weekdays sleep duration. Women and men who ate or drank <1 h before bedtime, v. those who did not, had 35 min (95% CI (30,39)) and 25 min (95 % CI (21,29)) longer sleep duration, respectively, as well as increased odds of WASO; women (OR=2·03, 95% CI (1·66,2·49)) and men (OR=2·64, 95% CI (2·08,3·36)). As the interval of eating or drinking prior to bedtime expanded, odds of short and long sleep durations and WASO decreased. This population-based data linked eating or drinking <1 h before bedtime to longer sleep duration, but increased WASO. Eating or drinking further from bedtime lowers the odds of short and long sleep duration and WASO. Causal pathways are difficult to discern, though inefficient sleep after late-night eating could increase WASO and trigger compensatory increases in sleep duration.

The Association Between Sleep Duration and Sleep Timing and Insulin Resistance Among Adolescents in Mexico City

PURPOSE

Emerging evidence suggests that short sleep duration and delayed sleep timing may be independently related to insulin resistance (IR), although findings are mixed. Our aim was to investigate associations between sleep duration and timing with insulin resistance among adolescents.

METHODS

The analytic sample included 384 Mexican adolescents from a birth cohort study who took part in a follow-up study beginning in 2015. Insulin and glucose were measured in fasting serum, and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated (marker of insulin resistance; [insulin x glucose]/22.5). Sleep duration and midpoint were measured by actigraphy for 7 days after the visit and for analysis were separated by weekdays and weekends. In full and sex-stratified regression analysis, sleep duration and midpoint were exposures, and the log HOMA-IR was the outcome, adjusting for age.

RESULTS

The mean age of the sample was 13.8 ± 1.93 with 51% female. Shorter sleep duration on weekdays was associated with higher log HOMA-IR (β = -.049, 95% confidence interval [CI] -.097 to -.0009). Later midpoints on weekdays and the weekend were independently associated with higher log HOMA-IR (β = .0408, 95% CI -.0049 to .087, and β = .0486, 95% CI .0042 to .093, respectively). Girls showed stronger associations than boys for both sleep duration and timing with HOMA-IR.

CONCLUSIONS

Sleep duration and sleep timing were independently associated with insulin resistance, and associations were more pronounced among girls.

Meta-analysis of age and actigraphy assessed sleep characteristics across the lifespan

STUDY OBJECTIVES

Sleep quantity and continuity vary across the lifespan. Actigraphy is a reliable and widely-used behavioral measure of sleep in research and personal health monitoring. This meta-analysis provides a novel examination of whether age (in years) is associated with actigraphy-assessed sleep across the lifespan.

METHODS

A systematic search of PubMed, Embase.com, Cochrane CENTRAL, and PsycINFO using "actigraphy" and "sleep" terms provided 7,079 titles/abstracts; studies of individuals with known psychiatric or medical comorbidities were excluded. Ninety-one articles (N = 23,365) provided data for six meta-analyses examining sleep duration (k = 89), sleep efficiency (k = 58), bedtime (k = 19) and waketime (k = 9) for individuals ages 6-21, and bedtime (k = 7) and waketime (k = 7) for individuals ages 22 and older.

RESULTS

At older ages, sleep duration was shorter (r = -0.12) and sleep efficiency was lower (r = -0.05). Older age was associated with later bedtime (r = 0.37) and wake-up time (r = 0.24) from ages 6-21, whereas older age was associated with earlier bedtime (r = -0.66) and wake-up time (r = -0.59) for ages 22 and above. The strength of these associations was modified by study continent, but not by any other moderator.

CONCLUSIONS

Age was negatively associated with actigraphy-assessed sleep duration and efficiency, but the effects were small in magnitude. On the other hand, large associations were observed between age and sleep timing, despite a smaller literature and the absence of analyzable data for ages 30-60. Changes in sleep timing, rather than changes in sleep duration or continuity, may better characterize the effects of age on human sleep.

Adolescent sleep timing and dietary patterns in relation to DNA methylation of core circadian genes: a pilot study of Mexican youth

Mistimed sleep/wake and eating patterns put shift workers at increased risk for cardiometabolic disease, and epigenetic modification of circadian genes has been proposed as a mechanism. Although not as extreme as shift workers, adolescents often have delayed sleep timing and irregular eating patterns. The aim was to assess whether sleep midpoints - median of bed and wake time - and dietary patterns in adolescents were associated with DNA methylation of circadian genes. The study population included 142 Mexican youth (average age of 14.0 (SD = 2.0) years, 49% male). Average sleep midpoint over weekdays was estimated with actigraphy. Diet was assessed with a semi-quantitative food frequency questionnaire, and three dietary patterns were derived from principal component analysis, a Plant-based & lean proteins pattern, a Meat & starchy pattern, and an Eggs, milk & refined grain pattern. DNA methylation was quantified in blood leukocytes with the Infinium MethylationEPIC BeadChip, and data from 548 CpG sites within 12 circadian genes were examined. Linear regression analyses, adjusted for sex, age, and % monocytes, showed that later sleep timing was associated with higher DNA methylation of several circadian genes, notably with RORB, PER1, CRY2, and NR1D1. Each of the dietary patterns examined was also related to circadian gene DNA methylation, but the Eggs, milk & refined grain pattern ('breakfast' pattern) had the clearest evidence of relationships with circadian genes, with inverse associations (lower DNA methylation) across all 12 genes. Findings suggest that timing-related sleep and eating behaviours among adolescents could result in epigenetic modification of clock genes.

Sleep duration and fragmentation in relation to leukocyte DNA methylation in adolescents

STUDY OBJECTIVES

Sleep deprivation and low sleep quality are widespread among adolescents, and associate with obesity risk. Plausible mediators include diet and physical activity. Another potential interrelated pathway, as yet unexplored in adolescents, could involve epigenetic modification of metabolism genes.

METHODS

In a cohort of 351 Mexico City adolescents (47% male; mean [SD] age = 14 [2] years), 7-day actigraphy was used to assess average sleep duration, sleep fragmentation, and movement index. DNA isolated from blood leukocytes was bisulfite-converted, amplified, and pyrosequenced at four candidate regions. Linear mixed models evaluated sex-stratified associations between sleep characteristics (split into quartiles [Q]) and DNA methylation of each region, adjusted for potential confounders.

RESULTS

Mean sleep duration was 8.5 [0.8] hours for boys and 8.7 [1] hours for girls. There were sex-specific associations between sleep duration and LINE-1 (long interspersed nuclear element) methylation. Boys with longer sleep duration (Q4) had lower LINE-1 methylation than boys in the 3rd quartile reference category, while girls with both longer and shorter sleep duration had higher LINE-1 methylation compared to Q3. Longer sleep duration was associated with higher H19 methylation among girls (comparing highest to third quartile, -0.9% [-2.2, 0.5]; p, trend = 0.047). Sleep fragmentation was inversely associated with peroxisome proliferator-activated receptor alpha (PPARA) methylation among girls (comparing highest to lowest fragmentation quartile, 0.9% [0.1 to 1.8]). Girls also showed an inverse association between sleep fragmentation and hydroxysteroid (11-beta) dehydrogenase 2 (HSD11B2; Q4 to Q1, 0.6% [-1.2%, 0%]).

CONCLUSIONS

Sleep duration and fragmentation in adolescents show sex-specific associations with leukocyte DNA methylation patterns of metabolism genes.

Bedtimes and Blood Pressure: A Prospective Cohort Study of Mexican Adolescents

INTRODUCTION

Hypertension affects up to 5% of children worldwide and predicts later cardiovascular morbidity. Associations of short sleep and hypertension have been frequently reported in adults but less consistently in children. This study aims to examine the role of late bedtimes, a marker of short sleep duration, and potentially misaligned circadian rhythms, on incident elevated blood pressure (BP) in a large cohort of Mexican children.

METHODS

Participants included 2,033 adolescents recruited from public schools in Morelos, Mexico, free from elevated BP (<90th sex, age, and height-standardized percentile). Fourteen months later, all adolescents had a second BP assessment. We abstracted baseline habitual bedtimes from questionnaires to evaluate the association between bedtime and elevated BP incidence (≥90th percentile). Risk ratios and 95% confidence intervals were estimated with discrete-time mixed survival models, adjusting for potential confounders and accounting for clustering by school.

RESULTS

Participants were 12.5 (SD = 0.6) years old at baseline. At the follow-up visit 10% of adolescents had developed elevated BP. Compared to participants with a habitual weekday bedtime between 9 and 10 pm, those with a weekday bedtime 11 pm or later had a 1.87 times higher risk of developing elevated BP over the follow-up period (95% CI = 1.09, 2.21), after accounting for confounders. Participants with earlier weekday bedtimes also had a higher risk of elevated BP (RR = 1.96; 95% CI = 1.27, 3.01). The associations persisted after accounting for wake time.

CONCLUSION

These data showed a U-shaped association between weekday bedtime and elevated/high BP risk among Mexican adolescents.

Poor sleep quality is associated with obesity and depression in farmers

BACKGROUND

Farmers' work schedules can result in inconsistent sleep patterns which negatively impact health.

PURPOSE

To explore the relationships between sleep, obesity, and depression in working, older farmers and their spouses. Covariates included body mass index (BMI), age, and gender.

METHODS

Sleep quality, BMI, and depression were assessed in farmers (n = 1,394) 50 years and older. Bivariate associations among all covariates (i.e., age, gender, BMI, sleep) and dependent variable (i.e., depression) were analyzed using Pearson's correlation. Multivariable associations of the Center for Epidemiologic Studies Depression Scale (CESD). BMI with other study variables were assessed using linear regression.

RESULTS

BMI was positively associated with sleep apnea symptoms (p ≤ 0.0001) and CESD scores (p = 0.0006). Participants with difficulty falling asleep were more likely to have poor sleep quality (p ≤ 0.0001) and higher CESD scores (p ≤ 0.0001). Poor sleep quality was associated with higher CESD scores (p ≤ 0.0001). Increased age, female gender, higher BMI, sleep apnea symptoms, and poorer sleep quality were all predictive of higher depressive symptoms.

DISCUSSION

Farmers have unique lifestyles that increase the risk of poor sleep. Screening for sleep pattern disruption and understanding its impact could result in lower rates of depression and obesity in this group of high-risk individuals.