Midpoint Of Sleep Research Articles

Relationships of Sleep Duration, Midpoint, and Variability with Physical Activity in the HCHS/SOL Sueño Ancillary Study

Relationships of Sleep Duration, Midpoint, and Variability with Physical Activity in the HCHS/SOL Sueño Ancillary Study

Effect of Social Jetlag on Sleep and Respiratory Disturbance in Young Patients with Obstructive Sleep Apnea Syndrome

Objectives Circadian misalignment may increase the risk of obesity and related obstructive sleep apnea (OSA). Considerable young adults have social jetlag (SJL), which is defined as the time discrepancy between workdays and free days. We aim to evaluate the relationship between SJL and sleep and respiratory disturbance in patients with untreated OSA patients. Methods A total of 180 OSA patients under the age of 50 [mean 38.3±8.0 y, 93.3% male, mean apnea-hypopnea index (AHI) 38.2±27.4 /h] were recruited from the university affiliated sleep clinic and fulfilled sleep-related questionnaires including Munich Chronotype Questionnaire (MCTQ). SJL was defined as the difference in sleep midpoints between work and free days. Patients were divided into three groups with SJL less than 1 hour, 1–2 hours, and 2 hours or more and the clinical and sleep data of each group were compared. Results 51.6% (n=93) suffered from significant SJL (≥1 h). Patients with ≥2h of SJL (16.6%, n=30) had the largest neck circumference (NC). AHI and sleep parameters were not significantly different among groups except lowest oxygen saturation (LoS) was the lowest in the group of ≥2 h. SJL was positively correlated with body mass index and NC and negatively correlated with LoS after adjusting for age and sex. Conclusions About a half of young adults with OSA have significant SJL more than 1 h. This study suggests that SJL is associated with being overweight, while it seems not increase the severity of OSA nor deteriorate sleep quality in young adults. Keywords: Obstructive sleep apnea, Circadian rhythm, Chronotype, Sleep, Obesity

The impact of summer vacation on children\u2019s obesogenic behaviors and body mass index: a natural experiment

BackgroundChildren’s BMI gain accelerates during summer. The Structured Days Hypothesis posits that the lack of the school day during summer vacation negatively impacts children’s obesogenic behaviors (i.e., physical activity, screen time, diet, sleep). This natural experiment examined the impact of summer vacation on children’s obesogenic behaviors and body mass index (BMI).MethodsElementary-aged children (n = 285, 5-12 years, 48.7% male, 57.4% African American) attending a year-round (n = 97) and two match-paired traditional schools (n = 188) in the United States participated in this study. Rather than taking a long break from school during the summer like traditional schools, year-round schools take shorter and more frequent breaks from school. This difference in school calendars allowed for obesogenic behaviors to be collected during three conditions: Condition 1) all children attend school, Condition 2) year-round children attend school while traditional children were on summer vacation, and Condition 3) summer vacation for all children. Changes in BMI z-score were collected for the corresponding school years and summers. Multi-level mixed effects regressions estimated obesogenic behaviors and monthly zBMI changes. It was hypothesized that children would experience unhealthy changes in obesogenic behaviors when entering summer vacation because the absence of the school day (i.e., Condition 1 vs. 2 for traditional school children and 2 vs. 3 for year-round school children).ResultsFrom Condition 1 to 2 traditional school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 24.2, 95CI = 10.2, 38.2), screen time minutes (∆ = 33.7, 95CI = 17.2, 50.3), sleep midpoint time (∆ = 73:43, 95CI = 65:33, 81:53), and sleep efficiency percentage (−∆ = 0.7, 95CI = -1.1, − 0.3) when compared to year-round school children. Alternatively, from Condition 2 to 3 year-round school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 54.5, 95CI = 38.0, 70.9), light physical activity minutes (∆ = − 42.2, 95CI = -56.2, − 28.3) MVPA minutes (∆ = − 11.4, 95CI = -3.7, − 19.1), screen time minutes (∆ = 46.5, 95CI = 30.0, 63.0), and sleep midpoint time (∆ = 95:54, 95CI = 85:26, 106:22) when compared to traditional school children. Monthly zBMI gain accelerated during summer for traditional (∆ = 0.033 95CI = 0.019, 0.047) but not year-round school children (∆ = 0.004, 95CI = -0.014, 0.023).ConclusionsThis study suggests that the lack of the school day during summer vacation negatively impacts sedentary behaviors, sleep timing, and screen time. Changes in sedentary behaviors, screen time, and sleep midpoint may contribute to accelerated summer BMI gain. Providing structured programming during summer vacation may positively impact these behaviors, and in turn, mitigate accelerated summer BMI gain.Trial registrationClinicalTrials.gov Identifier: NCT03397940. Registered January 12th 2018.

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

PurposeEmerging 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. MethodsThe 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. ResultsThe 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. ConclusionsSleep duration and sleep timing were independently associated with insulin resistance, and associations were more pronounced among girls.

Effects of ambulatory blood pressure monitoring on sleep in healthy, normotensive men and women.

To determine the effect of ambulatory blood pressure monitoring (ABPM) on sleep quality among healthy adults and to explore possible effect modification by demographics. We examined data from 192 relatively healthy young (median age: 31; 33% men, 18% with clinic BP >130/80 mmHg) participants in an observational study of sleep and arterial stiffness. Demographic/health questionnaires were completed. A wrist-based accelerometer assessed sleep for seven nights, and sleep duration, wakefulness after sleep onset (WASO), fragmentation (physical restlessness), midpoint, and efficiency were estimated. ABPM was conducted for one 36-h period, including one actigraphy night. Within-subject comparisons indicated that WASO and fragmentation were higher, midpoint was later, and efficiency was lower on the ABPM night (Ps < 0.001-0.038). Neither age nor sex moderated these associations. Among older adults, a later midpoint and worse fragmentation were observed with ABPM (Ps = 0.002-0.010). There was also a main effect of sex: men demonstrated shorter sleep duration, greater WASO and fragmentation, and less efficiency than women (Ps = 0.002-0.046). With ABPM, women had worse fragmentation and a later midpoint (Ps = 0.002-0.049); for men, WASO and fragmentation were worse (Ps = 0.003-0.023). Importantly, this study does not address whether the effect of wearing ABPM on sleep in turn affects BP during sleep. ABPM appears to modestly disturb actigraphy-assessed sleep among healthy adults. Researchers and clinicians should consider the downstream effects of performing ABPM and whether these effects are more pronounced in those who typically experience sleep disturbance.

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

ABSTRACT 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 timing, sleep consistency, and health in adults: a systematic review.

The objective of this systematic review was to examine the associations between sleep timing (e.g., bedtime/wake-up time, midpoint of sleep), sleep consistency/regularity (e.g., intra-individual variability in sleep duration, social jetlag, catch-up sleep), and health outcomes in adults aged 18 years and older. Four electronic databases were searched in December 2018 for articles published in the previous 10 years. Fourteen health outcomes were examined. A total of 41 articles, including 92 340 unique participants from 14 countries, met inclusion criteria. Sleep was assessed objectively in 37% of studies and subjectively in 63% of studies. Findings suggest that later sleep timing and greater sleep variability were generally associated with adverse health outcomes. However, because most studies reported linear associations, it was not possible to identify thresholds for "late sleep timing" or "large sleep variability". In addition, social jetlag was associated with adverse health outcomes, while weekend catch-up sleep was associated with better health outcomes. The quality of evidence ranged from "very low" to "moderate" across study designs and health outcomes using GRADE. In conclusion, the available evidence supports that earlier sleep timing and regularity in sleep patterns with consistent bedtimes and wake-up times are favourably associated with health. (PROSPERO registration no.: CRD42019119534.) Novelty This is the first systematic review to examine the influence of sleep timing and sleep consistency on health outcomes. Later sleep timing and greater variability in sleep are both associated with adverse health outcomes in adults. Regularity in sleep patterns with consistent bedtimes and wake-up times should be encouraged.

Sleep health, diseases, and pain syndromes: findings from an electronic health record biobank.

Implementation of electronic health record biobanks has facilitated linkage between clinical and questionnaire data and enabled assessments of relationships between sleep health and diseases in phenome-wide association studies (PheWAS). In the Mass General Brigham Biobank, a large health system-based study, we aimed to systematically catalog associations between time in bed, sleep timing, and weekly variability with clinical phenotypes derived from ICD-9/10 codes. Self-reported habitual bed and wake times were used to derive variables: short (<7 hours) and long (≥9 hours) time in bed, sleep midpoint, social jetlag, and sleep debt. Logistic regression and Cox proportional hazards models were used to test cross-sectional and prospective associations, respectively, adjusted for age, gender, race/ethnicity, and employment status and further adjusted for body mass index. In cross-sectional analysis (n = 34,651), sleep variable associations were most notable for circulatory system, mental disorders, and endocrine/metabolic phenotypes. We observed the strongest associations for short time in bed with obesity, for long time in bed and sleep midpoint with major depressive disorder, for social jetlag with hypercholesterolemia, and for sleep debt with acne. In prospective analysis (n = 24,065), we observed short time in bed associations with higher incidence of acute pain and later sleep midpoint and higher sleep debt and social jetlag associations with higher incidence of major depressive disorder. Our analysis reinforced that sleep health is a multidimensional construct, corroborated robust known findings from traditional cohort studies, and supported the application of PheWAS as a promising tool for advancing sleep research. Considering the exploratory nature of PheWAS, careful interrogation of novel findings is imperative.

Relationships of Sleep Duration, Midpoint, and Variability with Physical Activity in the HCHS/SOL Sueño Ancillary Study

ABSTRACT Objective/Background Short and long sleep duration, later sleep midpoint, and greater intra-individual sleep variability are associated with lower physical activity, but previous research lacks objective and concurrent assessment of sleep and physical activity. This cross-sectional study examined whether sleep duration, midpoint, and variability in duration and midpoint were related to wrist actigraphy-measured physical activity. Participants Participants were 2156 Hispanics/Latinos in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Sueño Ancillary Study. Methods Participants wore Actiwatch devices to measure sleep and physical activity via the wrist for ≥5 days. Physical activity was defined as minutes/day in the upper quartile of the sampling distribution’s non-sleep activity, capturing light to vigorous physical activity. Results An inverse linear relationship between sleep duration and physical activity was found such that each additional sleep hour related to 29 fewer minutes of physical activity (B = −28.7, SE = 3.8), p < .01). Variability in sleep midpoint was also associated with physical activity; with each 1-hr increase in variability there were 24 more minutes of physical activity (B = 24.2, SE = 5.6, p < .01). In contrast, sleep midpoint and variability in duration were not associated with physical activity. Sensitivity analyses identified an association of short sleep duration and greater variability in sleep duration with greater accelerometry-derived moderate-to-vigorous physical activity measured at the HCHS/SOL baseline (M = 2.1 years before the sleep assessment). Conclusions Findings help clarify inconsistent prior research associating short sleep duration and sleep variability with greater health risks but also contribute novel information with simultaneous objective assessments.

The Parent's Chronotype and Child's Sleeping Quality in Association with Relationship Satisfaction.

The prospective Ulm-SPATZ study was investigated to assess the role of child sleeping quality between 4 to 6 years of age in affecting a partner’s sleeping and relationship satisfaction within a couple. The study was conducted using a triadic approach in which the child was included in the Actor-Partner-Interdependence Model (APIM). Sleeping quality of the child was determined by using the German version of the children’s sleep habits questionnaire, sleeping features of the parents were assessed by using the Munich chronotype questionnaire, and the partner relationship assessment was performed by employing the German version of the parenting stress index questionnaire. In 211 German triads, we observed that sleeping characteristics and partner relationship scores at different child ages are consistent for both men and women. Higher and statistically significant sleep duration, time spent in bed, the midpoint of sleep, time getting out of bed, and sleep onset in women compared to men during the working days were observed. The APIM analyses showed a significant direct effect of child sleep quality on the partner relationship satisfaction. In women, a mediated effect of child sleep quality acted through sleep duration and time spent in bed on the partner relationship satisfaction score during both free and working days. In men, low child sleep quality was found to be associated with increased sleep onset during both free and working days. Child sleep quality influences relationship satisfaction mostly in mothers, likely because of their higher involvement in childcare during working days. Distress in the couple could be counteracted by a major involvement of the fathers in child management.

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

IntroductionMercury 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. MethodsThe 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. ResultsDuring 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). ConclusionsThere 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.

Real-time mobile monitoring of bipolar disorder: a review of evidence and future directions.

Rapidly accumulating data from mobile assessments are facilitating our ability to track patterns of emotions, behaviors, biologic rhythms, and their contextual influences in real time. These approaches have been widely applied to study the core features, traits, changes in states, and the impact of treatments in bipolar disorder (BD). This paper reviews recent evidence on the application of both passive and active mobile technologies to gain insight into the role of the circadian system and patterns of sleep and motor activity in people with BD. Findings of more than two dozen studies converge in demonstrating a broad range of sleep disturbances, particularly longer duration and variability of sleep patterns, lower average and greater variability of motor activity, and a shift to later peak activity and sleep midpoint, indicative of greater evening orientation among people with BD. The strong associations across the domains tapped by real-time monitoring suggest that future research should shift focus on sleep, physical/motor activity, or circadian patterns to identify common biologic pathways that influence their interrelations. The development of novel data-driven functional analytic tools has enabled the derivation of individualized multilevel dynamic representations of rhythms of multiple homeostatic regulatory systems. These multimodal tools can inform clinical research through identifying heterogeneity of the manifestations of BD and provide more objective indices of treatment response in real-world settings. Collaborative efforts with common protocols for the application of multimodal sensor technology will facilitate our ability to gain deeper insight into mechanisms and multisystem dynamics, as well as environmental, physiologic, and genetic correlates of BD.

Association between short sleep duration and metabolic syndrome in Chinese children and adolescents

BackgroundThe relationship between short sleep duration and metabolic syndrome (MetS) in children and adolescents has been inconsistent. This study aimed to examine the association between short sleep duration and MetS in Chinese children and adolescents. MethodsData were from a cross-sectional survey conducted in Jinan, China between September 2013 and November 2014. A total of 1008 children and adolescents aged 6–17 years were included. Sleep duration was self-reported by participants and categorized as normal or short (<9 h in children aged 6–12 years or <8 h in adolescents aged 13–17 years) according to the recommendations of the American Academy of Sleep Medicine. MetS was defined based on the modified criteria of the National Cholesterol Education Program Adult Treatment Panel III. ResultsAfter adjusted for sex, age, parental education levels, and midpoint of sleep, compared with normal sleep duration, short sleep duration was associated with increased odds of MetS (odds ratio [OR]: 1.79, 95% confidence interval [CI]: 1.09–2.95) and abdominal obesity (OR: 1.60, 95% CI: 1.14–2.25). In the subgroups stratified by age and sex, compared with normal sleep duration, short sleep duration was associated with increased odds of abdominal obesity (OR: 2.34, 95% CI: 1.07–5.13) in girls aged 6–12 years; short sleep duration was associated with increased odds of MetS (OR: 2.49, 95% CI: 1.06–5.84), abdominal obesity (OR: 2.30, 95% CI: 1.10–4.82), and high TG (OR: 2.63, 95% CI: 1.11–6.21) in boys aged 13–17 years. ConclusionsShort sleep duration associated with higher odds for MetS in Chinese children and adolescents. Interventions to improve sleep duration could help prevent and control MetS among children and adolescents.

Increase in eveningness and insufficient sleep among adults in population-based cross-sections from 2007 to 2017

ObjectivesShort or long sleep duration, insufficient sleep, and Evening chronotype associate with many health issues and increased risk for mortality. Understanding population-level changes in sleep and chronotype frequencies is important for assessing the prospective health status of the society and future challenges on health care at a national level. This study examines the cross-sectional differences in sleep duration, insufficient sleep, and chronotype frequencies indicated by both circadian preference and habitual sleep-wake rhythm among adults living in Finland during a 10-year period of 2007–2017. MethodsThe study sample (N = 18 039) was derived from he National FINRISK 2007 and 2012 Studies, and The FinHealth 2017 Study, each consisting of a random sample of adults, aged 25–74 years and as stratified by age and sex, and providing the self-reported data on their circadian preference, habitual daily sleep duration, insufficient sleep and bedtimes.T ResultsDuring the 10 years, sleep duration decreased, insufficient sleep increased and circadian preference towards eveningness increased significantly in each 10-year age group and among both sexes. In general, eveningness was more common among younger adults in all the study years but, as compared to 2012, in 2017 bedtimes and midpoint of sleep were more advanced among this age group while sleep-wake rhythm became more delayed in older adults. The decrease in sleep duration and the increase in insufficient sleep were emphasized in younger adults and especially in women, whereas the increase in eveningness in older adults and in men. ConclusionsThe evolution of sleep and chronotype frequencies from 2007 to 2017 is alarming, as these might lead to a poorer health status in the adult population and thus cause more strain to the public health. The mismatch between sleep-wake behavior and circadian preference was emphasized in young adults, indicating a greater risk for circadian misalignment in the Finnish adult population in the future, if there will not be any interventions to correct this mismatch.

Depression and anxiety symptoms correlate with diurnal preference, sleep habits, and Per3 VNTR polymorphism (rs57875989) in a non-clinical sample

BackgroundEvidences suggest that alterations in circadian rhythms trigger the development of mental disorders. Eveningness, sleep behavior, and circadian genes polymorphisms have been associated with depression and anxiety symptomatology. However, the mechanism underlying these interactions is not well understood. We investigated the contribution of diurnal preference, sleep habits, and PER3 VNTR polymorphism (rs57875989) to depression and anxiety symptoms in a Northeast sample from the Brazilian population. MethodsEight hundred and four young adults completed the Morningness-Eveningness (MEQ), Munich Chronotype (MCTQ), Center for Epidemiologic Studies – Depression (CES-D), and Beck Anxiety Inventory (BAI) questionnaires. All participants were genotyped and linear regression was performed to test the interactions between the genetic /behavioral variants and depression/ anxiety symptoms. ResultsEveningness and sleep behaviors (bedtime, wake-up time, sleep duration, and midpoint of sleep) were correlated with depression symptomatology, specifically in somatic factors of the CES-D questionnaire. No correlation was found between diurnal preference/sleep habits with anxiety symptoms for both BAI total score and its factors. However, women with PER34/4 genotype showed less interpesonal affect in depression symptomatology and more anxiety symptoms in four factors of the BAI questionnaire. LimitationsMainly because this study was based on self-report questionnaires and was limited to undergraduate students aging 18 to 30 years old. ConclusionThese results reinforce a role for sleep and diurnal preference in depression, and PER3 VNTR polymorphism in anxiety symptomatology, particularly in women.

Social jetlag is associated with cardiorespiratory fitness in male but not female adolescents

IntroductionCardiorespiratory fitness (CRF) is a vital sign that can improve risk classification for adverse health outcomes. While lifestyle-related factors are associated with CRF, few have examined the influence of sleep characteristics, especially in youths. Social jetlag, a mismatch between one's biological clock and sleep schedule, is prevalent in adolescents and associated with increased adiposity, though its relationship with CRF is unclear. ObjectiveTo quantify the relationship between social jetlag and CRF, independent of other sleep characteristics. MethodsThis cross-sectional sample includes 276 New Zealand adolescents (14–18 years, 52.5% female). CRF (VO2max) was estimated from a 20-m multi-stage shuttle run. Average sleep duration, sleep disturbances, social jetlag, physical activity, and the number of bedroom screens were estimated from validated self-report surveys. Social jetlag is the difference in hours between the midpoint of sleep during weekdays (school) and weekend days (free). Combined and sex-stratified linear regression assessed the association between sleep outcomes and CRF, controlling for relevant covariates. ResultsMales slept 17.6 min less, had less sleep disturbances, and a 25.1-min greater social jetlag than their female peers (all p < 0.05). A 1-h increase in social jetlag was associated with a 0.72 ml/kg/min decrease in VO2max (95% CI: −1.31, −0.14), independent of other sleep variables, which were not associated with CRF. Sex-specific models indicated an association in males (B −0.93, 95% CI: −1.76, −0.09), but not females (B −0.32, 95% CI: −1.18, 0.55). ConclusionsSocial jetlag is negatively associated with CRF in adolescent males and may be a simple, measurable target for public health interventions.

Children's objective sleep assessed with wrist-based accelerometers: strong heritability of objective quantity and quality unique from parent-reported sleep.

Children's poor sleep is a risk factor for lower cognitive functioning and internalizing and externalizing problems. It is unclear whether genetic and environmental influences vary based on sleep assessment and no studies to date have examined genetic and environmental contributions to links between multiple objective and subjective sleep indicators. Further, nearly all heritability studies rely on subjective parent- or self-report measures of sleep duration and problems. Given these gaps in the literature, we (1) modeled genetic and environmental influences on multiple objective and subjective sleep indicators and (2) estimated genetic and environmental covariances between objective and subjective sleep indicators in middle childhood. Participants were 608 twin children (MZ = 178, same-sex DZ = 234, opposite-sex DZ = 190) assessed at 8 years of age (SD = 0.63 years). Objective nighttime sleep duration, efficiency, sleep onset latency (SOL), midpoint time, and midpoint variability were collected from actigraph watches worn for 7 nights (Mnights = 6.83, SD = 0.62). Children's nighttime sleep duration and daytime sleepiness were assessed via parent report. Findings suggested high additive genetic influence on objective sleep quantity and quality, whereas objective SOL, sleep midpoint time, midpoint variability, parent-reported sleep duration, and daytime sleepiness were largely influenced by the shared environment. Common genetic factors explained associations between objective sleep quantity and quality, but genetics did not account for links with parent-reported sleep duration, midpoint time, or midpoint variability. Thus, objective and parent-reported assessments of children's sleep have unique genetic etiologies and should not be used interchangeably in the sleep literature.

Sleep Regularity and Cardiometabolic Heath: Is Variability in Sleep Patterns a Risk Factor for Excess Adiposity and Glycemic Dysregulation?

Night-to-night variability in sleep patterns leads to circadian disruption and, consequently, could increase cardiometabolic risk. The purpose of this review is to summarize findings from studies published between 2015 and 2020 examining various measures of night-to-night variability in sleep in relation to metabolic syndrome (MetS), type 2 diabetes (T2D), and their risk factors. We illustrate a potential causal pathway between irregular sleep patterns and T2D, highlighting knowledge gaps along the way. Across different measures of sleep variability, irregular sleep patterns were associated with poorer cardiometabolic outcomes. Higher standard deviations (SD) across nights of sleep duration and onset or midpoint of sleep were associated with increased odds of having MetS and clusters of metabolic abnormalities as well as greater adiposity and poorer glycemic control. Conversely, greater regularity of rest-activity patterns related to lower risk for T2D. Social jetlag was associated with glycemic dysregulation, adiposity, T2D, and MetS. These associations are often observed in both metabolically healthy and unhealthy individuals; both higher SD of sleep duration and social jetlag relate to poorer glucose regulation in individuals with diabetes. There is consistent evidence of associations of sleep variability with increased risk for adiposity, glucose dysregulation, T2D, and MetS. Although experimental evidence is needed to determine causation, there is support to recommend stabilizing sleep patterns for cardiometabolic risk prevention.

Eveningness associates with lower physical activity from pre- to late adolescence

ObjectiveAdolescence is often associated with decline in physical activity (PA) and a circadian shift towards eveningness, but it is not known whether these transitions are intertwined. We explored longitudinally and in cross-section how chronotype and genetic liability for morningness associate with PA as self-reported and measured by actigraphy in early and late adolescence. MethodsOur sample comes from a longitudinal Finnish community-cohort born in 1998 with information on actigraph-based PA and objectively measured sleep–wake rhythm based on midpoint of sleep at ages 12 (N = 353, girls = 187) and 17 (N = 171, girls = 98). Information on self-reported circadian preference and subjective PA was available at age 17. The summarized genetic effects of multiple single nucleotide polymorphism for morningness was assessed by calculating polygenic score (PGS) based on the results on a recent genome-wide association study (GWAS). ResultsPA declined by 40% (p < 0.0001) in boys and by 32% in girls (p < 0.0001) from age 12 to 17. Later midpoint of sleep correlated significantly with lower level of general, light and moderate to vigorous PA only at age 12 (all p < 0.05) but not at age 17 (all p ≥ 0.36). However, those with circadian preference more towards eveningness at age 17 had more sedentary behavior (p < 0.01) and a lower level of general (p = 0.01), light (p < 0.01) and moderate to vigorous PA (p < 0.05). They also had poorer subjective assessment of their fitness level (p < 0.01) and they exercised less (all p ≤ 0.05). The decline in objectively measured PA and increase in sedentary behavior from age 12 to 17 was emphasized among those with circadian preference towards eveningness (p < 0.05). PGS for morningness was not significantly associated with PA in adolescence (all p ≥ 0.13). ConclusionsFindings of this study highlighted the influence of circadian preference on physical activity behavior in adolescence. Self-assessed circadian preference towards eveningness associated with lower PA and greater decline of it during adolescence. Furthermore, PA declined significantly especially among boys from early to late adolescence. Interventions encouraging physical activity should target specifically evening-oriented adolescents.

Multidimensional sleep health is not cross-sectionally or longitudinally associated with adiposity in the Study of Women's Health Across the Nation (SWAN)

ObjectivesThe association between sleep and adiposity (indexed by body mass index or waist-to-hip ratio) has typically been evaluated using a single dimension of self-reported sleep. However, other dimensions and behavioral measures of sleep may also be associated with adiposity. This study evaluated whether multidimensional sleep health calculated from actigraphy and self-report was longitudinally associated with adiposity in a sample of midlife women who have a high prevalence of sleep disturbances and adiposity. DesignLongitudinal study with 11–14 years of follow-up time between the sleep health assessment and body mass index / waist-to-hip ratio measurements. ParticipantsTwo hundred and twenty-one midlife women enrolled in the Study of Women's Health Across the Nation Sleep Study. MeasurementsMultidimensional sleep health was quantified using actigraphy (M[SD] = 29.1[7.2] nights) measures of sleep efficiency, midpoint, duration, regularity, and self-report measures of alertness and satisfaction. Each component was dichotomized and summed; higher values indicated better sleep health. Height, body weight, and waist and hip circumference were measured at the sleep study and at follow-up. Linear regression models were used to assess associations between sleep health and adiposity, adjusting for demographic and menopausal covariates. ResultsThere was no substantial within-person change in adiposity over time. Better sleep health was cross-sectionally and longitudinally associated with lower adiposity in unadjusted, but not in adjusted, models. Individual sleep health components were not associated with adiposity after adjustment. ConclusionWe did not observe cross-sectional or longitudinal associations between multidimensional sleep health and adiposity. The sleep-adiposity link may be weaker in midlife adults than in other age groups.