The Impact of the Double School Shift System on Lifestyle Behaviors Among Mexican Adolescents.

PURPOSE: Early school start times could adversely impact adolescent sleep duration. They could also impact other behaviors like diet and physical activity, either directly or indirectly through effects on sleep. We examined whether the double school shift system was associated with sleep, diet, and physical activity behaviors among Mexican adolescents. METHODS: The analytic sample included 305 Mexican adolescents from a cohort study (on average 14.53 ± 1.75 years old and 51% male). Sleep and physical activity were measured with wrist actigraphy, while diet and other lifestyle behaviors were assessed with questionnaires. Regression analyses were conducted to compare lifestyle behaviors between the morning and afternoon school shifts, adjusting for potential confounders. RESULTS: Adolescents attending the morning school shift (44%) had pronounced differences in sleep compared to those attending afternoon shift, including a 1.77-hour shorter sleep duration on weekdays (95% CI -1.55, -2.00), a 0.40-hour longer sleep duration on weekends (95% CI 0.10, 0.70), higher social jetlag (1.07 hours with a 95% CI of 0.87, 1.27), and an earlier chronotype. Morning shift students also had 0.85 hours longer sedentary time (95% CI 0.61, 1.10) and higher consumption of a meat and starchy food dietary pattern. Among boys only, morning shift was associated with a lower likelihood of smoking and higher consumption of a breakfast pattern. DISCUSSION: Overall, attending a morning school shift was associated with shorter sleep, more social jetlag, greater sedentary time, and higher consumption of a meat and starchy diet. However, among boys, a few healthier behaviors were observed for the morning versus afternoon shift.

Patterns of Sleep Duration and Metabolic Biomarkers Across the Menstrual Cycle.

CONTEXT: Along the menstrual cycle, associations between inconsistent sleep duration and levels of metabolic biomarkers are uncertain and could involve fluctuations in estrogen concentrations. OBJECTIVE: To examine associations between patterns of sleep duration and metabolic biomarkers across two menstrual cycles within a cohort of premenopausal women. METHODS: The BioCycle Study was conducted in New York between 2005-2007, enrolling 259 premenopausal women over two menstrual cycles. This micro-longitudinal cohort study involved intensive data collection including daily sleep diaries and biomarker assessments of leptin, insulin, and glucose at 16 key points timed to menstrual cycle phases. We considered dynamic sleep duration, as hours slept one night or as mean hours slept during the two nights prior to each biomarker assessment. Variability in habitual sleep duration, i.e., reported daily sleep duration, summarized across both menstrual cycles. Variation in habitual sleep duration was computed using L-moments, a robust version of dispersion, skewness, and kurtosis. To examine associations between patterns of sleep duration and metabolic biomarkers, we fitted a series of linear mixed models with random intercepts and inverse probability weighting. These models were adjusted for potential demographic, lifestyle, health confounders, and menstrual cycle phase. RESULTS: Sleep duration one night or two nights prior to clinic visits were not associated with metabolic biomarker measures we assessed. However, overall variability (dispersion) in habitual sleep duration was associated with lower mean insulin HOMA-IR levels, but not glucose. Moreover, extreme short or long bouts of sleep duration was associated with higher mean levels of leptin, insulin, and HOMA-IR. CONCLUSIONS: These data suggest that variation in habitual sleep duration along the menstrual cycle may be associated with metabolic function.

Delayed Sleep Midpoint Across Pregnancy Is Associated with Excessive Gestational Weight Gain.

Background: Changes in sleep patterns and body weight occur during pregnancy, yet it is unclear whether sleep patterns are related to gestational weight gain (GWG). This study examined the relationship between maternal sleep across pregnancy and excessive GWG. Methods: Participants from the Michigan Archive for Research on Child Health (MARCH) cohort study, who had singleton births and provided information on fall-asleep and wake-up times during early (first or second) and the third trimesters, were included (n = 372). Changes in sleep duration and sleep midpoints throughout pregnancy were calculated. Prepregnancy weight and the last maternal weight before delivery were used to calculate GWG, which was categorized into groups (inadequate, adequate, and excessive). Poisson regression models were used to examine associations between sleep changes and excessive GWG, adjusted for age, race, gestational age, prepregnancy body mass index, income, fetus gender, physical activity, added sugar, and fruit and vegetable intake. Results: Excessive GWG was observed in 46.5% of women, and was more common among those with prepregnancy obesity (p < 0.001). Women who delayed sleep midpoint by 1 hour (or more) from the early trimester assessment to the third trimester experienced higher risk of excessive GWG (Risk ratio: 1.3; 95% confidence interval: 1.1-1.7). Single time points of sleep duration and sleep midpoint or changes in sleep duration were not related to GWG. Conclusions: Delay in sleep midpoint from early-mid pregnancy to the third trimester was associated with excessive GWG. Health professionals should consider changes in sleep patterns during pregnancy to identify those prone to excessive GWG.

Breastfeeding Duration and Cardiometabolic Health during Adolescence: A Longitudinal Analysis.

OBJECTIVE: To investigate the longitudinal association between breastfeeding duration and cardiometabolic health, using repeated measures study design among children and adolescents. STUDY DESIGN: This study included 634 offsprings aged 10 to 21 years (52% female) from the Early Life Exposure in Mexico to Environmental Toxicants birth cohort followed up to four time points during adolescence. Breastfeeding duration was prospectively quantified using questionnaires during early childhood. Cardiometabolic risk factors, body composition, and weight-related biomarkers were assessed as outcomes during adolescent follow-up visits. Sex-stratified linear mixed-effects models were used to model the association between quartiles of breastfeeding duration and outcomes, adjusting for age and additional covariates. RESULTS: Median breastfeeding duration was 7 months (minimum = 0, maximum = 36). Boys in the second quartile (median breastfeeding = 5 months) had lower total fat mass % (ß (SE) -3.2 (1.5) P = .037), and higher lean mass % (3.1 (1.6) P = .049) and skeletal muscle mass % (1.8 (0.8) P = .031) compared with the reference group (median breastfeeding = 2 months). A positive linear trend between breastfeeding duration and trunk lean mass % (0.1 (0.04) P = .035) was found among girls. No association was found with other cardiometabolic indicators. CONCLUSION: Despite sex-specific associations of breastfeeding duration with body composition, there was a lack of substantial evidence for the protective effects of breastfeeding against impaired cardiometabolic health during adolescence among Mexican youth. Further longitudinal studies with a robust assessment of breastfeeding are recommended.

Manganese and Sleep Outcomes in United States Adults: Results from the 2017-2020 National Health and Nutrition Examination Survey (NHANES).

BACKGROUND: Manganese (Mn) is an essential micronutrient, but inadequate or excess Mn intake can have a detrimental impact on human health. Despite the essentiality, little is known about the relationship between Mn and sleep. OBJECTIVE: This study aimed to examine the relationship between blood Mn concentrations and sleep outcomes in US adults. METHODS: This cross-sectional study used data on blood Mn and sleep from the 2017-2020 National Health and Nutrition Examination Survey (NHANES) (n = 8356, age ≥18 y). Multivariable logistic regression was used to examine associations between quintiles of blood Mn concentrations and subjective sleep outcomes (short sleep duration, late sleep midpoint, trouble sleeping, and obstructive sleep apnea [OSA] symptoms), adjusting for age, gender, body mass index, race/ethnicity, income, smoking, inflammation-adjusted serum ferritin concentration (iron status), caffeine, and alcohol intake. Gender-stratified models were used due to interactions with gender. RESULTS: The mean (SE) blood Mn concentration was 9.7 (0.1) µg/L in US adults. In males, a nonlinear association was noted in the relationship between blood Mn levels and short sleep duration on weekdays and weekends. The third Mn quintile (Q3) group had lower odds of short sleep duration (<7 h) on weekdays (odds ratio [OR]=0.6, 95% confidence interval [CI]: 0.4, 0.9) than the lowest Mn quintile (Q1, reference) after adjusting for covariates in males. The second Mn quintile (Q2) group had lower odds of late sleep midpoint on weekdays than Q1 (OR=0.6, 95% CI: 0.4, 0.8). In females, Q2 group had lower odds of OSA symptoms than Q1 (OR: 0.6, 95% CI: 0.4, 0.9). No relationship was noted between Mn and trouble sleeping. CONCLUSIONS: Gender differences exist in the association between Mn and sleep in adults. Q1 group had the poorest sleep outcomes, including higher odds of short sleep duration (in males), late sleep midpoint (in males), and OSA symptoms (in females).

Iron Deficiency and Vitamin D Deficiency Are Associated with Sleep in Females of Reproductive Age: An Analysis of NHANES 2005-2018 Data.

BACKGROUND: Iron and vitamin D deficiencies have been implicated in sleep disturbance. Although females are more susceptible to these deficiencies and frequently report sleep-related issues, few studies have examined these associations in females. OBJECTIVE: This study investigates the association of iron and vitamin D deficiencies on sleep in a nationally representative sample of females of reproductive age. METHODS: We used 2 samples of 20-49-y-old non-pregnant females from National Health and Nutrition Examination Survey (NHANES) 2005-2008 (N = 2497) and NHANES 2005-2010 and 2015-2018 (N = 6731) to examine the associations of iron deficiency (ID), iron deficiency anemia (IDA), vitamin D deficiency (VDD), vitamin D inadequacy (VDI), and the joint association of both deficiencies with sleep duration, latency, and quality. Sleep outcomes were measured using a self-reported questionnaire. We used the body iron model based on serum ferritin and serum soluble transferrin receptor to identify ID, along with hemoglobin to identify IDA cases. In addition, 25-hydroxyvitamin D levels were used to determine VDD and VDI cases. Logistic regression was used to evaluate these associations, adjusting for potential confounders. In addition, we assessed the multiplicative and additive interactions of both deficiencies. RESULTS: ID and IDA were associated with poor sleep quality, with 1.42 [95% confidence interval (CI): 1.02, 2.00)] and 2.08 (95% CI: 1.29, 3.38) higher odds, respectively, whereas VDD and VDI were significantly associated with short sleep duration, with 1.26 (95% CI: 1.02, 1.54) and 1.22 (95% CI: 1.04, 1.44) higher odds, respectively. Subjects with both nutritional deficiencies had significantly higher odds of poorer sleep quality compared with subjects with neither condition. For sleep quality, a significant multiplicative interaction was observed between ID and VDD (P value = 0.0005). No associations were observed between study exposures and sleep latency. CONCLUSIONS: Among females of reproductive age, iron and vitamin D deficiencies are associated with sleep health outcomes. The potential synergistic effect of both deficiencies warrants further assessment.

Early-to-mid pregnancy sleep and circadian markers in relation to birth outcomes: An epigenetics pilot study.

Maternal sleep and circadian health during pregnancy are emerging as important predictors of pregnancy outcomes, but examination of potential epigenetic mechanisms is rare. We investigated links between maternal leukocyte DNA methylation of circadian genes and birth outcomes within a pregnancy cohort. Women (n = 96) completed a questionnaire and provided a blood sample at least once during early-to-mid pregnancy (average gestation weeks = 14.2). Leukocyte DNA was isolated and DNA methylation (average percent of methylation) at multiple CpG sites within BMAL1, PER1, and MTNR1B genes were quantified by pyrosequencing. Birth outcomes including gestational age at delivery, birthweight, and head circumference were abstracted from medical charts. Linear regression analyses were run between each CpG site with birth outcomes, adjusting for important confounders. Sleep duration and timing were assessed as secondary exposures. Higher methylation of a CpG site in PER1 was associated with smaller log-transformed head circumference (ß=-0.02 with 95% CI -0.02 to 0.01; P, trend = 0.04). Higher methylation of MTNR1B (averaged across sites) was associated with lower log-transformed birthweight (-0.08 with 95% CI -0.16 to -0.01; P, trend = 0.0495). In addition, longer sleep duration was associated with higher birthweight (0.10 with 95% CI 0.02 to 0.18 comparing > 9 h to < 8 h; P, trend = 0.04). This pilot investigation revealed that higher methylation of PER1 and MTNR1B genes, and sleep duration measured in early-to-mid pregnancy were related to birth outcomes.

Plasma Fatty Acid Biomarkers of Dairy Consumption Are Associated with Sex-Dependent Effects on Metabolic Syndrome Components in Mexican Adolescents.

INTRODUCTION: During adolescence, dairy product intake has shown conflicting associations with metabolic syndrome (MetS) components, which are risk factors for cardiovascular disease (CVD). This study aims to investigate the association between plasma fatty acids (FAs) C15:0, C17:0, and t-C16:1n-7, as biomarkers of dairy intake, with MetS and its components in Mexican adolescents. METHODS: A sample of 311 participants from the Early Life Exposure in Mexico City to Environmental Toxicants (ELEMENT) cohort was included in this cross-sectional analysis. FA concentrations were measured in plasma as a percentage of total FA. We used quantile regression models stratified by sex to evaluate the association between FA quantiles and MetS components, adjusting for age, socioeconomic status (SES), sedentary behavior, BMI z-score, pubertal status, and energy intake. RESULTS: We found significant associations between dairy biomarkers and the median of MetS variables. In females, t-C16:1n-7 was associated with a decrease of 2.97 cm in WC (Q4 vs. Q1; 95% CI: -5.79, -0.16). In males, C15:0 was associated with an increase of 5.84 mm/Hg in SBP (Q4 vs. Q1; CI: 1.82, 9.85). For HDL-C, we observed opposite associations by sex. C15:0 in males was associated with decreased HDL-C (Q3 vs. Q1: ß = -4.23; 95% CI: -7.98, -0.48), while in females, C15:0 and t-C16:1n-7 were associated with increased HDL-C (Q3 vs. Q1: ß = 4.75; 95% CI: 0.68, 8.82 and Q4 vs. Q1: ß = 6.54; 95% CI: 2.01, 11.07), respectively. Additionally, in both sexes, different levels of C15:0, C17:0, and t-C16:1n-7 were associated with increased triglycerides (TG). CONCLUSION: Our results suggest that adolescent dairy intake may be associated in different directions with MetS components and that associations are sex-dependent.

Cross-sectional associations between phthalates, phenols, and parabens with metabolic syndrome risk during early-to-mid adolescence among a cohort of Mexican youth.

BACKGROUND: Epidemiological studies on children and adults have linked toxicants from plastics and personal care products to metabolic disruption. Yet, the impact of endocrine-disrupting chemicals (EDCs) on adolescent metabolic syndrome (MetS) risk during early and mid-adolescence is unclear. METHODS: To examine the links between exposure to EDCs and MetS risk and its components, cross-sectional data from 344 Mexican youth in early-to-mid adolescence (10-17 years) were analyzed. Urinary biomarker concentrations of phthalates, phenol, and paraben analytes were measured from a single spot urine sample collected in 2015; study personnel obtained anthropometric and metabolic measures. We examined associations between summary phthalates and metabolites, phenol, and paraben analytes with MetS risk z-scores using linear regression, adjusted for specific gravity, sex, age, pubertal status, smoking, alcohol intake, physical activity level, and screen time. As a secondary aim, mediation analysis was conducted to evaluate the role of hormones in the association between summary phthalates with lipids and MetS risk z-scores. RESULTS: The mean (SD) age was 13.2 (1.9) years, and 50.9% were female. Sex-stratified analyses revealed associations between summary phthalates and lipids ratio z-scores, including Σ DEHP [ß = 0.21 (95% CI: 0.04, 0.37; p < 0.01)], phthalates from plastic sources (Σ Plastic) [ß = 0.22 (95% CI: 0.05, 0.39; p < 0.01)], anti-androgenic phthalates (Σ AA) [ß = 0.22 (95% CI: 0.05, 0.39; p < 0.01)], and individual phthalate metabolites (MEHHP, MEOHP, and MECPP) among males. Among females, BPA [ß = 0.24 (95% CI: 0.03, 0.44; p < 0.05)] was positively associated with lipids ratio z-score and one phenol (2,5 DCP) [ß = 0.09 (95% CI: 0.01, 0.18); p < 0.05)] was associated with increased waist circumference z-score. Results showed no evidence of mediation by hormone concentrations in the association between summary phthalates with lipids ratio or MetS risk z-scores. CONCLUSION: Higher EDC exposure was positively associated with serum lipids during adolescence, particularly among males.

Sleep Disparities Across Pregnancy: A Michigan Cohort Study.

Introduction: Poor sleep health during pregnancy is related to adverse pregnancy outcomes. This study aims to identify sociodemographic characteristics associated with sleep health during pregnancy and to examine how they relate to changes in sleep during pregnancy. Materials and Methods: Participants (n = 458) were from the Michigan Archive for Research on Child Health, which is a prospective pregnancy cohort. Sociodemographic characteristics and self-reported sleep timing and quality were collected in phone interviews. This longitudinal study collected sleep parameters once during the early trimesters and once during the third trimester. Fall asleep and wake-up times were used to calculate sleep duration and sleep midpoint. Results: Compared to the third trimester, sleep duration was 12 minutes longer (p = 0.02), fall asleep time was 21 minutes earlier (p < 0.001), and the midpoint of sleep was 12 minutes earlier (p = 0.01) in early trimesters. Shorter sleep duration was noted in younger women. Sleep midpoint was later in those who were younger, overweight, or obese, racial minorities, unmarried, and with lower educational levels or socioeconomic status, and who smoked before pregnancy after adjusting for covariates. After controlling for confounders, women who were not working for pay had higher likelihood of reduced sleep duration, and women who were unmarried were more likely to have a delayed sleep midpoint in the third trimester compared to the early trimesters. Conclusions: This study suggests that sleep parameters changed during pregnancy and sleep health differed by sociodemographic characteristics. Understanding sleep disparities could help with early detection of at-risk populations during prenatal care.

Associations between exposure to phthalates, phenols, and parabens with objective and subjective measures of sleep health among Mexican women in midlife: a cross-sectional and retrospective analysis.

Endocrine-disrupting chemicals (EDCs) may impact sleep during the menopausal transition by altering sex hormones. However, these studies are scarce among Latin American women. This investigation utilized cross-sectional and retrospective data from midlife women enrolled in the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) study to examine associations between exposure to EDCs (phthalates, phenols, and parabens) and sleep health measures. For cross-sectional analyses, single spot urine samples were collected between 2017-2019 from a pilot sample of women (N = 91) of midlife age to estimate the urinary concentration of individual phthalates, phenols, and parabens and to calculate the summary concentration of phthalate mixtures. Seven-day nightly sleep duration, midpoint, and fragmentation were obtained from wrist-actigraphy devices and estimated from the actigraphy data using a pruned dynamic programming algorithm. Self-reported poor sleep quality was assessed by one item from the Pittsburgh Sleep Quality Index (PSQI). We examined associations between urinary summary phthalate mixtures, phthalate metabolites, phenol, and paraben analytes with each sleep measure using linear or logistic (to compute odds of poor sleep quality only) regression models adjusted for specific gravity, age, and socioeconomic status. We ran similar regression models for retrospective analyses (N = 74), except that urine exposure biomarker data were collected in 2008 when women were 24-50 years old. At the 2017-2019 midlife visit, 38% reported poor sleep quality. Cross-sectionally, EDCs were associated with longer sleep duration, earlier sleep timing, and more fragmented sleep. For example, every 1-unit IQR increase in the phenol triclosan was associated with a 26.3 min per night (95% CI: 10.5, 42.2; P < 0.05) longer sleep duration and marginally associated with 0.2 decimal hours (95% CI: -0.4, 0.0; P < 0.10) earlier sleep midpoint; while every 1-unit IQR increase in the phthalate metabolite MEHP was associated with 1.1% higher sleep fragmentation (95% CI: 0.1, 2.1; P < 0.05). Retrospective study results generally mirrored cross-sectional results such that EDCs were linked to longer sleep duration, earlier sleep timing, and more fragmented sleep. EDCs were not significantly associated with odds of self-reported poor sleep quality. Results from cross-sectional and retrospective analyses revealed that higher exposure to EDCs was predictive of longer sleep duration, earlier sleep timing, and more fragmented sleep among midlife women.

Sleep duration and timing are prospectively linked with insulin resistance during late adolescence.

OBJECTIVE: The aim of this study was to evaluate whether short sleep duration or later sleep timing is a risk factor for insulin resistance (IR) in late adolescence. METHODS: Mexico City adolescents enrolled in a longitudinal birth cohort (ELEMENT) took part in two study visits during peri-puberty that occurred approximately 2 years apart. IR was assessed with serum glucose and insulin. Four groups were defined using puberty-specific cut points: no IR over the follow-up period, transition from normal to IR, transition from IR to normal, and IR at both time points. Baseline sleep assessments were measured with 7-day wrist actigraphy. Multinomial logistic regression models were used to evaluate associations between sleep duration and timing with homeostatic model assessment of insulin resistance categories, adjusting for age, sex, and baseline pubertal status. RESULTS: Adolescents who were ≥ 1 hour below the sleep duration recommendations-for-age were 2.74 times more likely to develop IR (95% CI: 1.0-7.4). Similarly, adolescents who were in the latest category of sleep midpoint (>4:33 a.m.) were more likely than those with earliest midpoints (1 a.m.-3 a.m.) to develop IR (odds ratio = 2.63, 95% CI: 1.0-6.7). Changes in adiposity over follow-up did not mediate sleep and IR. CONCLUSIONS: Insufficient sleep duration and late sleep timing were associated with development of IR over a 2-year period in late adolescence.

Prenatal dietary patterns in relation to adolescent offspring adiposity and adipokines in a Mexico City cohort.

Maternal diet during pregnancy has been associated with obesity among offspring. The extent to which trimester-specific dietary patterns are associated with markers of adiposity during adolescence remains unclear. We examined associations between prenatal diet patterns with adolescent offspring measures of adiposity and adipokines in 384 mother-adolescent dyads from the Mexico City ELEMENT cohort. Trimester-specific diet patterns were derived from principal component analysis of food frequency questionnaire data. Adolescent anthropometry and serum leptin and adiponectin were measured at 10-17 years. Three maternal diet patterns were identified: Prudent Diet (PD), high in fish and vegetables, the High Meat and Fat Diet (HMFD), high in pork and processed meats, and the Transitioning Mexican Diet (TMD), high in corn tortillas and sugar-sweetened beverages. Multiple linear regression was used to estimate sex-stratified associations among quartiles of diet patterns with adiposity and adipokines, adjusting for maternal marital status, education, and parity. First trimester TMD was associated with greater anthropometric measures and higher leptin in females, while third trimester HMFD was associated higher body fat percentage, triceps thickness, waist circumference, and leptin, but lower adiponectin among males. Contrary to expectation, there were positive associations between the trimester 1 PD pattern and anthropometric measurements in females, and for trimester 2 HMFD and TMD patterns with adipokines among males. Findings suggest maternal diet patterns may influence offspring adiposity markers during adolescence in a sex-specific manner.

Urinary phthalates, phenols, and parabens in relation to sleep health markers among a cohort of Mexican adolescents.

INTRODUCTION: Emerging research has shed light on the potential impact of environmental toxicants on sleep health, however, it remains unclear if these associations exist during adolescence and whether associations differ by sex. This study aimed to examine associations between phthalates, parabens, and phenols on adolescent sleep health using cross-sectional data from 470 participants from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) study. MATERIAL AND METHODS: In 2015, spot urine samples were analyzed for exposure biomarkers of 14 phthalate metabolites, seven phenol, and four paraben analytes. Over seven consecutive days, sleep duration, midpoint, and fragmentation were assessed with wrist-actigraphy. We examined associations between summary phthalates, individual phthalate metabolites, and phenol and paraben analytes with mean weekday sleep duration, midpoint, and fragmentation using linear regression models adjusted for specific-gravity and sex, age, pubertal status, smoking and alcohol behavior, physical activity, and screen time. RESULTS: Mean (SD) age was 13.8 (2.1) years; 53.5 % were female. Σ Plastic - summary measure for toxicants from plastic sources - and Σ DEHP and its metabolites, were associated with longer sleep duration in the unstratified sample. To illustrate, every 1-unit log increase in Σ DEHP was associated with 7.7 min (95 % CI: 0.32, 15.1; p < 0.05) longer duration. Summary measures of toxicants from plastic sources, personal care products, anti-androgenic toxicants, and multiple individual phthalates, phenols, and parabens were associated with later midpoint. The midpoint associations were largely female-specific. There were no associations with sleep fragmentation. CONCLUSIONS: Higher EDC exposure may be related to longer sleep duration and later sleep timing during adolescence, and associations may vary by toxicant and according to sex.

Duration, timing, and consistency of sleep in relation to inflammatory cytokines in Mexican adolescents.

OBJECTIVE: To evaluate whether sleep duration, timing, and variability were associated with inflammatory cytokines in a cohort of Mexico City adolescents. METHODS: The analytic sample comprised >500 adolescents who were part of an ongoing longitudinal study in Mexico City. At two time points during mid-to-late puberty (average age 14, n = 391) and late-to-post puberty (average age 16, n = 345), adolescents completed a follow-up visit that included 7-day wrist actigraphy and clinical assessment of plasma inflammatory cytokines (high-sensitivity C-reactive protein, Interleukin 1ß, Interleukin 6, and Tumor Necrosis Factor ɑ). Sleep characteristics included weekday and weekend sleep duration and midpoint (median of bed and wake time), as well as sleep variability (SD of sleep duration across 7 days) and social jetlag (midpoint difference from weekdays to weekends). At each time point, multivariable linear regression models were run with log inflammatory levels as the outcome and categories of sleep characteristics as predictors, while adjusting for potential confounders (specific to each model). Analyses were run unstratified and sex-stratified. RESULTS: In the mid-to-late pubertal visit, weekday sleep duration was inversely associated with natural log hs-CRP after adjustment (Q4 vs Q1: ß = -0.41, 95% Confidence Interval (CI) -0.81 to -0.01) and later sleep midpoint was positively associated with log hs-CRP (Q4 vs Q1: ß = 0.55, 95% CI 0.13 to 0.97). Sleep duration variability was associated with higher IL-1ß among boys, while in girls social jetlag was associated with higher IL-1ß and weekend sleep duration was inversely associated with IL-6. At the late-to-post pubertal visit, there were few associations except for a positive association between weekday sleep duration and hs-CRP among boys (ß = 0.60, 95% CI 0.04 to 1.16) and a non-linear positive association between social jetlag and hs-CRP among girls (ß = 0.80, 95% CI 0.22 to 1.37 comparing 2 to 3 h of social jetlag vs <1 h). CONCLUSION: Later timing, shorter duration, and inconsistency of sleep were related to higher levels of inflammatory biomarkers, but associations were more evident at the mid-to-late pubertal visit than the late-to-post pubertal visit.

Early Childhood Diet in Relation to Toddler Nighttime Sleep Duration Trajectories.

The objective of this study was to evaluate whether dietary habits at age 2 associate with sleep duration trajectories through age 5 in children from north and central Appalachia. A total of 559 children from the Center for Oral Health Research in Appalachia (COHRA) cohort 2 were followed via caregiver phone interviews up to six times between ages 2 and 5. Exposures included data from the year 2 interview: sleep habits, household and demographic characteristics, meal patterns and consumption frequencies of fruits, vegetables, water, juice, milk, and soda. Sleep duration trajectories were identified using group-based trajectory models from ages 2 to 5. Three distinct nightly sleep duration trajectories were identified: short, increasing duration (4.5% of the study population); steady, 9 h of sleep (37.3%); and longer, slightly decreasing sleep duration (58.2%). Using multinomial logistic models that accounted for confounders, children with consistent meal patterns (i.e., meals and snacks at same time every day) and with higher fruit and vegetable consumption were more likely to follow the longer duration sleep trajectory compared to the steady sleep trajectory. In contrast, children who drank milk more frequently at age 2 were less likely to be in the longer duration sleep trajectory than the steady sleep trajectory.

Association between self-reported sleep duration and dietary quality in Mexican school-aged children.

Short sleep duration has been associated with poor diet quality in school-aged children in multiple populations. However, investigations of sleep and dietary quality in Mexican school-aged children are scarce. The main objective of this work was to assess the association between sleep duration and dietary quality in Mexican school-aged children stratified by sex. The data were collected from 373 (138 girls and 235 boys) elementary school children aged 6-12 years in Monterrey, Nuevo Leon, Mexico. Surveys collected information on general demographic characteristics and self-reported sleep duration. Diet was assessed with 24-h recalls, and dietary quality was calculated by the Healthy Eating Index (HEI-2015). Results indicated that overall mean sleep duration was 8.23 ± 1.06 h. From the total sample, 6.7% slept ≤6 h (not recommended), 55.8% 7-8 h (may be appropriate), and 37.5% ≥ 9 h (recommended). Average total HEI-2015 score was 64.6 (out of possible 100), with boys having lower HEI-2015 scores than girls (57.7 vs 69.4). Moreover, girls and boys with shorter sleep duration (≤6 h compared to ≥ 9 h) had lower HEI-2015 scores (-1.03 [95% CI -2.74, -0.47; p < .01] and -1.78 [95% CI -3.15, -0.86; p < .001], respectively). Regarding the individual components of dietary quality, those with ≤6 h of sleep had lower scores particularly in vegetables, protein sources, added sugars and saturated fats for girls and boys compared to those with ≥9 h. These findings suggest sleep may be an important determinant of dietary practices within the Mexican children.

Later sleep timing and social jetlag are related to increased inflammation in a population with a high proportion of OSA: findings from the Cleveland Family Study.

STUDY OBJECTIVES: To examine the association between sleep midpoint and inflammation in a population with a large proportion of individuals diagnosed with obstructive sleep apnea syndrome (OSAS), a group that is already prone to increased inflammation. METHODS: Subjects from the Cleveland Family Study underwent overnight polysomnography and completed surveys on sleep habits. Morning and evening blood samples were collected and assayed for proinflammatory biomarkers interleukin (IL)-1, IL-6, and tumor necrosis factor α (TNF-α). Linear regression models were used, adjusting for potential confounders and sleep duration. RESULTS: The study population included 587 adults (52.3% with OSAS). Mean ± standard deviation weekday sleep midpoint was 3.52 ± 2.09 (3:31 am) and weekend sleep midpoint was 4.46 ± 1.69 (4:28 am). The Mean difference between weekday and weekend sleep midpoint (social jetlag) was 0.94 ± 2.08 hours. After adjusting for OSA severity, greater social jetlag was associated with higher levels of the inflammatory cytokine IL-1 (beta: 0.435 pg/mL, 95% confidence interval [CI]: 0.091 to 0.779). Additionally, later timing of sleep during both the weekdays and the weekends was associated with increased levels of IL-6 (weekday beta: 0.182 pg/mL; 95% CI: 0.013 to 0.350; and weekend beta: 0.188 pg/mL; 95% CI: 0.004 to 0.373). No trends were observed with TNF-α and any sleep exposure. CONCLUSIONS: Later sleep timing was associated with elevated levels of IL-6 while increased social jetlag was associated with elevated levels of IL-1. Our results indicate that later sleep schedules and increased social jetlag may lead to higher inflammation, even after controlling for OSA severity. CITATION: Girtman KL, Baylin A, O'Brien LM, Jansen EC. Later sleep timing and social jetlag are related to increased inflammation in a population with a high proportion of OSA: findings from the Cleveland Family Study. J Clin Sleep Med. 2022;18(9):2179-2187.

Differential fat accumulation in early adulthood according to adolescent-BMI and heavy metal exposure.

INTRODUCTION: Heavy metals such as Lead (Pb) and Mercury (Hg) can affect adipose tissue mass and function. Considering the high prevalence of exposure to heavy metals and obesity in Mexico, we aim to examine if exposure to Pb and Hg in adolescence can modify how fat is accumulated in early adulthood. METHODS: This study included 100 participants from the ELEMENT cohort in Mexico. Adolescent Pb and Hg blood levels were determined at 14-16 years. Age- and sex-specific adolescent BMI Z-scores were calculated. At early adulthood (21-22 years), fat accumulation measurements were performed (abdominal, subcutaneous, visceral, hepatic, and pancreatic fat). Linear regression models with an interaction between adolescent BMI Z-score and Pb or Hg levels were run for each adulthood fat accumulation outcome with normal BMI as reference. RESULTS: In adolescents with obesity compared to normal BMI, as Pb exposure increased, subcutaneous (p-interaction = 0.088) and visceral (p-interaction < 0.0001) fat accumulation increases. Meanwhile, Hg was associated with subcutaneous (p-interaction = 0.027) and abdominal (p-interaction = 0.022) fat deposition among adolescents with obesity. CONCLUSIONS: Heavy metal exposure in adolescence may alter how fat is accumulated in later periods of life.