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.

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.

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).

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.

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.

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.

Sleep Difficulties among Mexican Adolescents: Subjective and Objective Assessments of Sleep.

OBJECTIVE/BACKGROUND: Self-reported sleep difficulties, such as insomnia symptoms, have been reported among adolescents. Yet, studies of their prevalence and correlates are scarce among Latin Americans. This study sought (1) to describe associations between sociodemographic and lifestyle factors with self-reported sleep difficulties and (2) to examine associations between self-reported sleep difficulties and actigraphy-based sleep. PARTICIPANTS: Participants included 477 Mexican adolescents from the ELEMENT cohort. METHODS: Over 7 days, self-reported sleep measures (hard time falling asleep, overall sleep difficulties, and specific types of sleep difficulties) were obtained from daily sleep diaries. Actigraphy-based sleep measures (duration, i.e. sleep onset to morning wake, midpoint, and fragmentation) were concurrently assessed using a wrist actigraph. RESULTS: Mean (SD) age was 15.9 (2.2) years, and 53.5% were females. Mean (SD) sleep duration was 8.5 (1.2) h/night. Half reported a hard time falling asleep at least 3 days, and 25% had sleep difficulties at least 3 days over 7 days. The 3 types of sleep difficulties commonly reported among the entire cohort were insomnia/restlessness (29%), environmental (27%), and mental/emotional difficulties (19%). Female sex, smoking behavior, and socioeconomic indicators were among the most consistent factors associated with sleep difficulties. Subjective sleep difficulties were associated with shorter sleep duration (ß = -20.8 [-35.3, -6.2] min), while subjective hard time falling asleep was associated with longer sleep duration (ß = 11.3 [4.6, 27.2] min). CONCLUSION: A high proportion of Mexican adolescents in the sample reported sleep difficulties. Findings demonstrate the importance of obtaining subjective and objective sleep measures for a more comprehensive assessment of adolescent sleep.

Associations between sleep duration and Mediterranean diet score in Costa Rican adults.

Both insufficient and excessive sleep duration have been associated with lower-quality diets in adult populations. However, investigations in Latin America, where different sleep norms may exist (e.g., daily napping), are scarce. Therefore, we examined whether weekday sleep duration and inconsistencies between weekday and weekend sleep duration were related to adherence to the Mediterranean diet among Costa Rican adults. The study population included 2169 controls (74% men) from a population-based case-control study. Usual sleep duration (weekday versus weekend) was self-reported and defined as short, recommended, and long (<7 h, 7-9 h, >9 h, respectively). Inconsistent weekday-weekend sleep duration was defined as >1-h difference. Diet was assessed with a food frequency questionnaire, and adherence to the Mediterranean diet was calculated with the Alternative Mediterranean Diet Score (AMED). Sex-stratified linear regression models were conducted with AMED score as a continuous outcome and sleep variables as categorical or dichotomous exposures (in separate models). Models were adjusted for age, area of residence, education, napping, caffeine intake, smoking status, type 2 diabetes mellitus, hypertension, and physical activity. Average (SD) hours of sleep per night reported were 7.0 (1.4) on weekdays and 7.3 (1.6) on weekends for men, and 7.0 (1.5) on weekdays and 7.2 (1.6) on weekends for women. Among women, sleep duration <7-h per night was associated with a lower AMED score compared to those with recommended sleep duration (ß: -0.35, CI: -0.63 to -0.07). Unstratified models showed a suggestive association between inconsistent weekday-weekend sleep and lower AMED scores that did not vary by sex (ß: -0.08, CI: -0.16, 0.006; P, interaction with sex = 0.93). Lastly, the napping frequency was not associated with AMED scores in any model. In conclusion, short and inconsistent sleep duration may affect the dietary patterns of Costa Ricans.

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.

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.

Parallel Assessment Challenges in Nutritional and Sleep Epidemiology.

Sleep has been consistently linked to health outcomes in clinical studies, but only in recent years has sleep become a focus in epidemiologic studies and public health. In particular, the sizable prevalence of insufficient sleep in the population warrants well-designed epidemiologic studies to examine its impact on public health. As a developing field, sleep epidemiology encounters methodological challenges similar to those faced by nutritional epidemiology research. In this article, we describe a few central challenges related to assessment of sleep duration in population-based studies in comparison with measurement challenges in nutritional epidemiology. In addition, we highlight 3 strategies applied in nutritional epidemiology to address measurement challenges and suggest ways these strategies could be implemented in large-scale sleep investigations.

Relationships of beverage consumption and actigraphy-assessed sleep parameters among urban-dwelling youth from Mexico.

OBJECTIVE: To examine whether usual beverage intake was associated with sleep timing, duration and fragmentation among adolescents. DESIGN: Usual beverage intake was assessed with a FFQ. Outcomes included sleep duration, midpoint (median of bed and wake times) and fragmentation, assessed with 7-d actigraphy. Sex-stratified linear regression was conducted with sleep characteristics as separate outcomes and quantiles of energy-adjusted beverage intake as exposures, accounting for age, maternal education, physical activity and smoking. SETTING: Mexico City. PARTICIPANTS: 528 adolescents residing in Mexico City enrolled in a longitudinal cohort. RESULTS: The mean age (sd) was 14·4 (2·1) years; 48 % were male. Among males, milk and water consumption were associated with longer weekday sleep duration (25 (95 % CI 1, 48) and 26 (95 % CI 4, 47) more minutes, in the 4th compared to the 1st quartile); and higher 100 % fruit juice consumption was related to earlier weekday sleep timing (-22 (95 % CI -28, 1) minutes in the 1st compared to the last quantile; P = 0·03). Among females, soda was associated with higher sleep fragmentation (1·6 (95 % CI 0·4, 2·8) % in the 4th compared to the 1st), and coffee/tea consumption was related to shorter weekend sleep duration (-23 (95 % CI -44, 2) minutes in the 4th compared to the 1st). CONCLUSIONS: Among females, adverse associations with sleep were observed for caffeinated drinks, while males with higher consumption of healthier beverage options (water, milk and 100 % juice) had evidence of longer and earlier-timed sleep. Potential mechanisms involving melatonin and tryptophan should be further investigated.

Association between pesticide exposure and sleep health among a representative sample of US adults: evidence from NHANES 2009-2014.

BACKGROUND: Data suggest that pesticides interact with the melatonin receptor, which may influence sleep. However, the link between pesticides and sleep remains unexplored among the general adult population. This study evaluated unstratified and sex-stratified associations between urinary pesticide exposure (N = 4,478) and self-reported acute household pesticide exposure (N = 14,956), with sleep health outcomes within a nationally representative sample of US adults. METHODS: Data from the National Health and Nutrition Examination Surveys (NHANES) 2009-2014 were combined for analysis of aim 1 and aim 2. Urinary pesticide metabolite concentrations served as biomarkers of pesticide exposure. Acute household pesticide exposure (if any chemical products were used in the home in the past seven days to control pests) was self-reported (yes/no). Insufficient sleep duration (< 7 h/night) and trouble sleeping (yes/no) were self-reported. Log-binomial regression models that accounted for complex survey weights and adjusted for confounders were used to compute prevalence ratios and 95% CI. RESULTS: Log urinary 3-phenoxybenzoic acid (3-PBA) was related to a higher probability of insufficient sleep [1.09 (95% CI: 1.00, 1.20), p = 0.04] and trouble sleeping [1.14 (95% CI: 1.02, 1.27), p = 0.02] among males. Self-reported acute household pesticide exposure was associated with a higher probability of insufficient sleep duration [1.16 (95% CI: 1.02, 1.32), p = 0.03] and trouble sleeping [1.20 (95% CI: 1.01, 1.44), p = 0.04] in the unstratified sample. Sex-stratified findings showed that associations between acute household pesticide exposure and trouble sleeping only persisted  among males [1.69 (95% CI: 1.27, 2.24), p < .001]. CONCLUSIONS: In summary, acute pesticide exposure may be detrimental to adult sleep health, particularly among US males.

Sleep Duration and Quality in Relation to Fruit and Vegetable Intake of US Young Adults: a Secondary Analysis.

BACKGROUND: Sleep is gaining recognition as a determinant of diet, yet this relationship remains understudied among young adults. We sought to examine how sleep duration and quality were related to fruit and vegetable (FV) intake within a diverse sample of young adults. METHODS: Participants (n = 1444) ages 21-30 (69% women, 15% African American, 35% full or part time in college) consuming < 5 servings/day of FV (eligibility criteria) completed a baseline survey to enroll in a randomized online FV intervention. Sleep questions included duration, perceived sleep quality, time to fall asleep, and insomnia symptoms. Overall and gender-stratified linear regression models compared average daily FV intake and sleep characteristics, adjusting for confounders. RESULTS: One-third (32%) of the participants reported < 7 h of sleep per night, and 36% noted insomnia symptoms ≥ 3 times per week. Women, a BMI > 30, African American race/ethnicity, less education, unemployment, higher depression, and stress were related to suboptimal sleep. Bivariate analyses showed that better sleep was associated with higher FV intake. After accounting for confounders, men with better sleep quality and shorter time to fall asleep had higher intakes of FV (1.12 serving/day difference in highest versus lowest quality [95% CI 0.48, 1.75] and a 0.52 serving/day higher intake difference for shortest versus longest fall asleep time [95% CI 0.90, 0.15], respectively). CONCLUSION: Sleep was highly prevalent in a diverse sample of community-based young adults and may contribute to lower FV intake among men. These associations highlight young adulthood as an important period for promoting healthy sleep habits.

Skipping breakfast and mood: The role of sleep.

BACKGROUND: Breakfast skipping has been related to poor mood, but the role of sleep in this relationship remains unclear. AIM: To evaluate whether breakfast skipping associated with mood independently of sleep, and whether sleep interacted with breakfast skipping. METHODS: During an in-person research visit, a sample of 329 adults completed questionnaires regarding last night's sleep, current morning breakfast intake, and mid-morning mood states. Sex-stratified linear regression models examined associations between breakfast skipping and mood and interactions with sleep. RESULTS: Among males, those who did not consume breakfast had less vigor independent of sleep (ß=-2.72 with 95% CI -4.91, -0.53). Among females, those who did not consume breakfast had higher feelings of anxiety (ß=1.21 with 95% CI -0.04, 2.47). Interaction analyses revealed that males with longer time to fall asleep and longer night-time awake time had higher depression scores in the presence of breakfast skipping, and females with more night-time awake time and shorter duration had higher fatigue and less vigor if they were also breakfast skippers. CONCLUSION: Breakfast skipping and poor sleep may jointly affect mood.

Plasma DHA Is Related to Sleep Timing and Duration in a Cohort of Mexican Adolescents.

BACKGROUND: Delayed sleep timing and short sleep duration represent a significant public health burden in adolescents. Whether intake of nutrients affects the pineal gland, where sleep/wake cycles are regulated, remains unclear. OBJECTIVES: In a cross-sectional analysis, we investigated whether plasma concentrations of DHA and arachidonic acid (AA), long-chain fatty acids that can be obtained through diet, were related to sleep timing and duration in adolescents. METHODS: The study population included 405 Mexico City adolescents (mean age ± SD = 14.2 ± 2.1 y; 48% males) who took part in a 2015-2016 follow-up visit as a part of an ongoing cohort study. Fatty acid concentrations were measured in plasma using GLC, as a percentage of total fatty acids. Sleep midpoint and duration were assessed with 7-d wrist actigraphy. We categorized DHA and AA plasma concentrations into quartiles (Q1-Q4; Q4 = highest fatty acids). We conducted cross-sectional linear regression analysis with sleep characteristics as separate outcomes and quartiles of DHA and AA as exposures, adjusting for sex, age, and BMI z-scores. RESULTS: Mean ± SD plasma DHA (as percentage of total fatty acids) was 1.2 ± 0.4%, whereas mean ± SD plasma AA was 6.2 ± 1.5%. In adjusted analysis, higher plasma DHA was linearly associated with longer sleep duration on the weekends; to illustrate, those in Q4 compared with Q1 had 32 min longer duration (95% CI: 7, 57; P trend = 0.005). Higher DHA was also associated with earlier sleep timing during weekdays and weekends, although in a nonlinear fashion. The largest difference was a 0.75-h (45-min) later sleep midpoint in Q2 compared with Q4 (95% CI: 0.36, 1.14). CONCLUSIONS: Plasma DHA was associated with earlier sleep timing and longer weekend sleep duration in Mexican adolescents. Whether DHA supplementation improves sleep in adolescent populations deserves consideration in randomized trials.

Mercury exposure in relation to sleep duration, timing, and fragmentation among adolescents in Mexico City.

INTRODUCTION: Mercury intoxication is known to be associated with adverse symptoms of fatigue and sleep disturbances, but whether low-level mercury exposure could affect sleep remains unclear. In particular, children may be especially vulnerable to both mercury exposures and to poor sleep. We sought to examine associations between mercury levels and sleep disturbances in Mexican youth. METHODS: The study sample comprised 372 youth from the Early Life Exposures to Environmental Toxicants (ELEMENT) cohort, a birth cohort from Mexico City. Sleep (via 7-day actigraphy) and concurrent urine mercury were assessed during a 2015 follow-up visit. Mercury was also assessed in mid-childhood hair, blood, and urine during an earlier study visit, and was considered a secondary analysis. We used linear regression and varying coefficient models to examine non-linear associations between Hg exposure biomarkers and sleep duration, timing, and fragmentation. Unstratified and sex-stratified analyses were adjusted for age and maternal education. RESULTS: During the 2015 visit, participants were 13.3 ± 1.9 years, and 48% were male. There was not a cross-sectional association between urine Hg and sleep characteristics. In secondary analysis using earlier biomarkers of Hg, lower and higher blood Hg exposure was associated with longer sleep duration among girls only. In both boys and girls, Hg biomarker levels in 2008 were associated with later adolescent sleep midpoint (for Hg urine in girls, and for blood Hg in boys). For girls, each unit log Hg was associated with 0.2 h later midpoint (95% CI 0 to 0.4), and for boys each unit log Hg was associated with a 0.4 h later sleep midpoint (95% CI 0.1 to 0.8). CONCLUSIONS: There were mostly null associations between Hg exposure and sleep characteristics among Mexican children. Yet, in both boys and girls, higher Hg exposure in mid-childhood (measured in urine and blood, respectively) was related to later sleep timing in adolescence.

Associations between Mental Workload and Sleep Quality in a Sample of Young Adults Recruited from a US College Town.

OBJECTIVE: To evaluate associations between perceived mental workload (number of hours spent studying and perceived mental intensity) and sleep quality among young adults. PARTICIPANTS: 656 participants [62% male, median age (IQR) = 20 (19, 21) years] recruited from a US college town. METHODS: As part of an online screener, participants answered questions about perceived workload and sleep quality (Pittsburgh Sleep Quality Index (PSQI)). Number of hours/day of mentally engaging work/study, and mental intensity score were the exposures, categorized into quartiles. Linear regression models were used for continuous sleep quality score, and modified Poisson models were used for poor quality sleep (>5 PSQI score) and individual sleep components, adjusting for sex, age, race, physical activity, and caffeine intake. RESULTS: Higher mental work-hours were associated with lower-quality sleep; those in the highest quartile of mental work-hours had a 28% higher likelihood of poor sleep quality (95% CI 2% to 62%). Higher mental intensity scores were also related to lower quality sleep; comparing the highest to the lowest quartiles, there was a 45% higher probability of being a poor sleeper (95% CI 15% to 83%). Associations with PSQI components were partly sex-specific: while both sexes had associations between mental intensity and short sleep, males had positive associations with poor sleep quality and sleep medication use. Conversely, females with higher mental intensity reported higher-quality sleep overall and lower sleep medication use but lower sleep efficiency. CONCLUSIONS: Higher mental workload is associated with lower overall sleep quality in young adults. Associations with individual sleep quality components differed by sex.

Associations between sleep duration and dietary quality: Results from a nationally-representative survey of US adults.

Insufficient sleep duration is a recognized determinant of cardiometabolic disease, with poor diet quality as a likely intermediate. Yet, inconsistencies in findings on sleep duration and diet quality among adult populations remain, particularly regarding a potential non-linear relationship. Thus, within a nationally representative survey of US adults (2011-2016 National Health and Nutrition Survey), we evaluated cross-sectional associations between sleep duration and diet quality. Self-reported typical sleep duration was categorized into four groups (≤5 h per night, 6 h, 7-8 h, and ≥9 h per night). Diet was assessed with two 24-h recalls (averaged), and diet quality was measured with the Healthy Eating Index-2015 (score range 0-100), which is comprised of 13 dietary components. Regression analyses that accounted for complex survey weights were used to compute multivariable-adjusted models of sleep duration categories and HEI-2015 overall scores, and individual HEI components. Within this nationally-representative sample of adults ≥18 years, 10% reported 5 or fewer hours of sleep, and 20% reported 6 h, while 12% obtained ≥9 h (long sleep duration). Compared to adults with 7-8 h of sleep, those with ≤5 h had 1.7 lower multivariable-adjusted HEI-2015 score (95% CI 0.6, 2.7), and those with ≥9 h had 1.2 lower adjusted HEI-2015 score (95% CI 0.2, 2.2). Upon examination of individual HEI-2015 components, short sleepers had lower consumption of healthier components (total fruits, whole fruits, total vegetables, greens and bean, whole grains, dairy, total protein, and seafood), while long sleepers had higher consumption of some unhealthier components (refined grains and added sugar) as well as some healthier components (dairy and total protein). In conclusion, within a nationally-representative US survey, a reverse U-shaped association was observed between sleep duration and dietary quality.