Nonlinear relationship between sleep midpoint and depression symptoms: a cross-sectional study of US adults.

BACKGROUND: Despite the close relationship between sleep-wake cycles and depression symptoms, the relationship between sleep midpoint and depression symptoms in adults remains understudied. METHODS: In this cross-sectional study, 18280 adults aged ≥ 18 years from the National Health and Nutrition Examination Survey (NHANES) 2015-2020 were analyzed. Covariates included age, sex, race/ethnicity, education level, marital status, family income, body mass index, smoking status, drinking status, physical activity, comorbid condition, sleep duration, and sleep disturbance were adjusted in multivariate regression models. RESULTS: Weighted restricted cubic spline based on the complex sampling design of NHANES showed that in participants with a sleep midpoint from 2:18 AM to 6:30 AM, the prevalence of depression symptoms increased by 0.2 times (adjusted odds ratio [OR] = 1.20, 95% confidence interval [CI]: 1.08-1.33) per 1-h increment in sleep midpoint compared to the reference point of 2:18 AM. For participants with a sleep midpoint after 6:30 AM and before 2:18 AM the next day, the relationship between sleep midpoint and depression symptoms was not significant after adjusting for all covariates (adjusted OR = 1.01, 95% CI: 0.99-1.03). CONCLUSIONS: The findings indicate a significant nonlinear association between sleep midpoint and depression symptoms in a nationally representative sample of adults.

Association of nocturnal sleep duration and sleep midpoint with osteoporosis risk in rural adults: a large-scale cross-sectional study.

BACKGROUND: Evidence has suggested the linkage between sleep habits and several metabolic diseases, but the association of sleep factors with bone health remains unclear, especially in regions with low economic levels. Thus, this study aimed to investigate the relationship of nocturnal sleep duration and sleep midpoint with the osteoporosis risk in a rural population. METHOD: Eligible subjects were derived from the Henan Rural Cohort Study. The Pittsburgh Sleep Quality Index was applied to collect sleep information including sleep initiating time and wake-up time. The bone mineral density of the calcaneus was measured by the ultrasonic bone density apparatus. Multivariable logistic regression models and restricted cubic splines were utilized to evaluate the odds ratio (OR) and 95% confidence intervals (95% CI). RESULTS: For 8033 participants, 1636 subjects suffered from osteoporosis. Compared with the reference group (7 ~ h group), the ORs and 95% CI of osteoporosis associated with duration of nocturnal sleep were 1.32 (1.10, 1.56), 1.59 (1.25, 2.01), and 1.82 (1.25, 2.65) in the 8 ~ h, 9 ~ h, and ≥ 10 h group, respectively. Additionally, the adjusted ORs and 95% CI were 1.20 (1.01, 1.44) in the early sleep midpoint group and 1.09 (0.92, 1.29) in the intermediate sleep midpoint, compared with the late. Furthermore, there was a joint effect of long duration of nocturnal sleep and the early sleep midpoint on osteoporosis. CONCLUSION: Long duration of nocturnal sleep and early sleep midpoint were independently and jointly associated with higher risk of osteoporosis in rural areas. TRIAL REGISTRATION: The Henan Rural Cohort Study has been registered at Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375.

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.

Higher Rates of Sleep Disturbance Among Offspring of Parents With Recurrent Depression Compared to Offspring of Nondepressed Parents.

OBJECTIVE: Youth who have a parent with recurrent depression are at high risk for mental health problems. There is a need to identify transdiagnostic and clinically actionable mechanisms that explain higher rates of psychopathology among high-risk youth. The present study sought to examine whether offspring of depressed parents exhibit greater parent- and self-reported sleep disturbance, shorter sleep duration, and later sleep midpoint compared to youth without any parental psychopathology. METHOD: Participants included 82 youth, including 41 youth (ages 9-13; mean age = 11.07 years; 46% female) deemed to be at high-risk based on having a parent with a recurrent depression history, and 41 (mean age = 11.16 years; 49% female) at low-risk based on having parents without any history of psychopathology. Youth and their parents completed measures of youth sleep disturbance, and youth completed measures of sleep duration and midpoint using a daily sleep diary for 9 days. RESULTS: Offspring of parents with depression exhibited more sleep disturbance (e.g., problematic nighttime behaviors and daytime sleepiness) than low-risk youth as reported by both parents and youth. For parent-reported sleep disturbance, there were also sex differences. High-risk girls had more sleep disturbance than high-risk boys or low-risk girls. There were no group differences for daily sleep duration and midpoint. CONCLUSION: Sleep disturbance may be an important area for assessment among offspring of parents with depression. Our findings highlight one potential transdiagnostic risk factor that may emerge among high-risk youth, and sex-specific differences in sleep disturbance, which have implications for prevention and intervention.

Development of Late Circadian Preference: Sleep Timing From Childhood to Late Adolescence.

OBJECTIVES: To assess differences relating to circadian preference in objectively measured sleep patterns from childhood to adolescence over a 9-year period. We hypothesized there is developmental continuity in sleep timing and duration according to circadian preference. STUDY DESIGN: Young participants (N = 111, 65% girls) from a community-based birth cohort underwent sleep actigraphy at mean ages 8.1 (SD = 0.3), 12.3 (SD = 0.5), and 16.9 (SD = 0.1) years. A short version of Morningness-Eveningness Questionnaire was administered in late adolescence. At each follow-up, sleep midpoint, duration, wake after sleep onset, sleep efficiency, and weekend catch-up sleep were compared between those reporting morning, intermediate, and evening preferences in late adolescence. RESULTS: Mixed model analyses indicated that sleep timing was significantly earlier among morning types compared with evening types at all ages (P values < .04). The mean differences in sleep midpoint between morning and evening types increased from a mean of 19 minutes (age 8), 36 minutes (age 12), to 89 minutes (age 17). The largest change occurred from age 12 to 17 years. Sleep duration, wake after sleep onset, sleep efficiency, and catch-up sleep did not differ according to circadian preference. CONCLUSIONS: This study found significant continuity in sleep timing from childhood to adolescence over 9 years, indicating that late circadian preference reported in late adolescence begins to manifest in middle childhood. Further studies are needed to establish whether sleep timing has its origins at an even earlier age.

Objectively measured short sleep duration and later sleep midpoint in pregnancy are associated with a higher risk of gestational diabetes.

BACKGROUND: Experimental and epidemiologic data suggest that among nonpregnant adults, sleep duration may be an important risk factor for chronic disease. Although pregnant women commonly report poor sleep, few studies objectively evaluated the quality of sleep in pregnancy or explored the relationship between sleep disturbances and maternal and perinatal outcomes. OBJECTIVE: Our objective was to examine the relationship between objectively assessed sleep duration, timing, and continuity (measured via wrist actigraphy) and maternal cardiovascular and metabolic morbidity specific to pregnancy. STUDY DESIGN: This was a prospective cohort study of nulliparous women. Women were recruited between 16 0/7 and 21 6/7 weeks' gestation. They were asked to wear a wrist actigraphy monitor and complete a daily sleep log for a period of 7 consecutive days. The primary sleep exposure variables were the averages of the following over the total valid nights (minimum 5, maximum 7 nights): short sleep duration during the primary sleep period (<7 h/night), late sleep midpoint (midpoint between sleep onset and sleep offset >5 am), and top quartile of minutes of wake time after sleep onset and sleep fragmentation index. The primary outcomes of interest were a composite of hypertensive disorders of pregnancy (mild, severe, or superimposed preeclampsia; eclampsia; or antepartum gestational hypertension) and gestational diabetes mellitus. We used χ2 tests to assess associations between sleep variables and categorical baseline characteristics. Crude odds ratios and 95% confidence intervals were estimated from univariate logistic regression models to characterize the magnitude of the relationship between sleep characteristics and hypertensive disorders of pregnancy and gestational diabetes. For associations significant in univariate analysis, multiple logistic regression was used to explore further the association of sleep characteristics with pregnancy outcomes. RESULTS: In all, 901 eligible women consented to participate; 782 submitted valid actigraphy studies. Short sleep duration and a later sleep midpoint were associated with an increased risk of gestational diabetes (odds ratio, 2.24; 95% confidence interval, 1.11-4.53; and odds ratio, 2.58; 95% confidence interval, 1.24-5.36, respectively) but not of hypertensive disorders. A model with both sleep duration and sleep midpoint as well as their interaction term revealed that while there was no significant interaction between these exposures, the main effects of both short sleep duration and later sleep midpoint with gestational diabetes remained significant (adjusted odds ratio, 2.06; 95% confidence interval, 1.01-4.19; and adjusted odds ratio, 2.37; 95% confidence interval, 1.13-4.97, respectively). Additionally, after adjusting separately for age, body mass index, and race/ethnicity, both short sleep duration and later sleep midpoint remained associated with gestational diabetes. No associations were demonstrated between the sleep quality measures (wake after sleep onset, sleep fragmentation) and hypertensive disorders or gestational diabetes. CONCLUSION: Our results demonstrate a relationship between short sleep duration and later sleep midpoint with gestational diabetes. Our data suggest independent contributions of these 2 sleep characteristics to the risk for gestational diabetes in nulliparous women.

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.

Bedsharing sleep characteristics in children with mild sleep-disordered breathing.

STUDY OBJECTIVES: Examine sleep patterns in children with sleep-disordered breathing (SDB) who habitually bedshare. METHODS: We evaluated associations of bedsharing with parent-reported (n=457) and actigraphy-based (n=258) sleep patterns in a diverse child sample (mean age 6.6±2.3 years, range 3.0-12.9) with mild SDB using baseline data from the Pediatric Adenotonsillectomy Trial for Snoring. Multivariable linear regressions examined associations between sleep patterns and bedsharing, adjusting for sociodemographic, child, and parent/environmental factors. Moderation effects were investigated using interaction terms. Analyses were stratified by age, categorizing children as younger (<6) and older (≥6) years. RESULTS: Bedsharing rates were 38%, with higher rates in younger (48%) vs. older (30%) children (p<0.001). In adjusted models, bedsharing was associated with about 30 minutes shorter actigraphy-derived nocturnal sleep duration (p=0.005) and parent-reported later sleep midpoint (p< 0.005) in younger children. In older children, associations of bedsharing with shorter parent-reported sleep duration were more pronounced in children with greater SDB symptom burden (p=0.02), and in children with higher ratings of anxiety (p=0.048) and depressive symptoms (p=0.02). CONCLUSIONS: In children with mild SDB, bedsharing is associated with shorter sleep duration and later sleep timing in younger children. In older children, these relationships were modified by child factors, including SDB symptom burden and internalizing symptoms. These findings suggest that whereas age and parenting factors may play a greater role in the younger group, SDB and internalizing symptoms may play more of a role in older children who bedshare, suggesting the need to address co-occurring medical and emotional problems in children with SDB. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Pediatric Adenotonsillectomy for Snoring (PATS); Identifier: NCT02562040.

Association of sleep timing with all-cause and cardiovascular mortality: the Sleep Heart Health Study and the Osteoporotic Fractures in Men Study.

STUDY OBJECTIVES: Previous studies have highlighted the importance of sleep patterns for human health. This study aimed to investigate the association of sleep timing with all-cause and cardiovascular disease mortality. METHODS: Participants were screened from two cohort studies: the Sleep Heart Health Study (SHHS; n = 4,824) and the Osteoporotic Fractures in Men Study (n = 2,658). Sleep timing, including bedtime and wake-up time, was obtained from sleep habit questionnaires at baseline. The sleep midpoint was defined as the halfway point between the bedtime and wake-up time. Restricted cubic splines and Cox proportional hazards regression analyses were used to examine the association between sleep timing and mortality. RESULTS: We observed a U-shaped association between bedtime and all-cause mortality in both the SHHS and Osteoporotic Fractures in Men Study groups. Specifically, bedtime at 11:00 pm and waking up at 7:00 am was the nadir for all-cause and cardiovascular disease mortality risks. Individuals with late bedtime (> 12:00 am) had an increased risk of all-cause mortality in SHHS (hazard ratio 1.53, 95% confidence interval 1.28-1.84) and Osteoporotic Fractures in Men Study (hazard ratio 1.27, 95% confidence interval 1.01-1.58). In the SHHS, late wake-up time (> 8:00 am) was associated with increased all-cause mortality (hazard ratio 1.39, 95% confidence interval 1.13-1.72). No significant association was found between wake-up time and cardiovascular disease mortality. Delaying sleep midpoint (> 4:00 am) was also significantly associated with all-cause mortality in the SHHS and Osteoporotic Fractures in Men Study. CONCLUSIONS: Sleep timing is associated with all-cause and cardiovascular disease mortality. Our findings highlight the importance of appropriate sleep timing in reducing mortality risk. CITATION: Ma M, Fan Y, Peng Y, et al. Association of sleep timing with all-cause and cardiovascular mortality: the Sleep Heart Health Study and the Osteoporotic Fractures in Men Study. J Clin Sleep Med. 2024;20(4):545-553.

Effects of sleep on breakfast behaviors in recently unemployed adults.

OBJECTIVES: Skipping meals is linked to negative cardiometabolic health outcomes. Few studies have examined the effects of breakfast skipping after disruptive life events, like job loss. The present analyses examine whether sleep timing, duration, and continuity are associated with breakfast eating among 186 adults who recently (past 90 days) experienced involuntary unemployment from the Assessing Daily Activity Patterns Through Occupational Transitions (ADAPT) study. METHODS: We conducted both cross-sectional and 18-month longitudinal analyses to assess the relationship between actigraphic sleep after job loss and breakfast eating. RESULTS: Later sleep timing was associated with a lower percentage of days breakfast was eaten at baseline (B = -0.09, SE = 0.02, P < .001) and longitudinally over 18 months (estimate = -0.04; SE = 0.02; P < .05). No other sleep indices were associated with breakfast consumption cross-sectionally or prospectively. CONCLUSIONS: Unemployed adults with a delay in sleep timing are more likely to skip breakfast than adults with an advancement in sleep timing. Future studies are necessary to test chronobiological mechanisms by which sleep timing might impact breakfast eating. With the understanding that sleep timing is linked to breakfast eating, the advancement of sleep timing may provide a pathway for the promotion of breakfast eating, ultimately preventing cardiometabolic disease.

Preconception sleep duration, sleep timing, and shift work in association with fecundability and live birth among women with a history of pregnancy loss.

OBJECTIVE: To evaluate the associations between preconception sleep characteristics and shift work with fecundability and live birth. DESIGN: Secondary analysis of the Effects of Aspirin in Gestation and Reproduction study, a preconception cohort. SETTING: Four US academic medical centers. PATIENT(S): Women aged 18-40 with a history of 1-2 pregnancy losses who were attempting to conceive again. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURES(S): We evaluated baseline, self-reported sleep duration, sleep midpoint, social jetlag, and shift work among 1,228 women who were observed for ≤6 cycles of pregnancy attempts to ascertain fecundability. We ascertained live birth at the end of follow up via chart abstraction. We estimated fecundability odds ratios (FORs) using discrete, Cox proportional hazards models and risk ratios (RRs) for live birth using log-Poisson models. RESULT(S): Sleep duration ≥9 vs. 7 to <8 hours (FOR: 0.81, 95% confidence interval [CI], 0.61; 1.08), later sleep midpoints (3rd tertile vs. 2nd tertile: FOR: 0.85; 95% CI, 0.69, 1.04) and social jetlag (continuous per hour; FOR: 0.93, 95% CI: 0.86, 1.00) were not associated with reduced fecundability. In sensitivity analyses, excluding shift workers, sleep duration ≥9 vs. 7 to <8 hours (FOR: 0.62; 95% CI, 0.42; 0.93) was associated with low fecundability. Night shift work was not associated with fecundability (vs. non-night shift work FOR: 1.17, 95% CI, 0.96; 1.42). Preconception sleep was not associated with live birth. CONCLUSION(S): Overall, there does not appear to be a strong association between sleep characteristics, fecundability, and live birth. Although these findings may suggest weak and imprecise associations with some sleep characteristics, our findings should be evaluated in larger cohorts of women with extremes of sleep characteristics. CLINICAL TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT00467363.

Validation of the Munich Chronotype Questionnaire (MCTQ) in Chinese college freshmen based on questionnaires and actigraphy.

The Munich Chronotype Questionnaire (MCTQ) was developed to determine an individual's chronotype, and it provides information about sleep and wake times separately for work and free days. However, the MCTQ has not been effectively verified using a large sample based on multiple questionnaires and actigraphy measures. Three sequential studies were conducted. Study 1 used a large sample (n = 1066) to investigate the chronotype of Chinese college freshmen and assess the validity of the MCTQ compared with the reduced Morningness-Eveningness Questionnaire (rMEQ), actigraphy, and other related questionnaires. Study 2 verified the MCTQ compared with a sleep diary. Study 3 examined the test-retest reliability of the MCTQ at the 2-year follow-up. The results showed that MCTQ parameters were significantly associated with rMEQ scores, the actigraphy-based mid-point of sleep, sleep quality, depression, and trait anxiety. In addition, all MCTQ variables were significantly related to the diary-based sleep mid-point. The test-retest reliability of the mid-point of sleep adjusted for sleep debt (MSFsc) and mid-point of sleep on free days (MSF) was acceptable. These results indicate that the MCTQ is a practical and efficient tool with good reliability. Its further development is important for the accurate assessment of chronotypes and clinical diagnoses of sleep.

From early birds to night owls: a longitudinal study of actigraphy-assessed sleep trajectories during the transition from pre- to early adolescence.

STUDY OBJECTIVES: Pre- and early adolescence are believed to constitute periods of important age-related changes in sleep. However, much of the research on these presumed developmental changes has used cross-sectional data or subjective measures of sleep, limiting the quality of the evidence. In addition, little is known about the development of certain features of the sleep-wake cycle pertaining to regularity (e.g. weekend-weekday differences and intra-individual variability) or circadian rhythms (e.g. sleep midpoint). METHODS: This study examined the sleep trajectories of 128 typically developing youth (69 girls) from ages 8 to 12 years on four sleep characteristics: sleep onset, sleep offset, total sleep time (TST), and sleep midpoint. For each of these characteristics, actigraphy-derived estimates of typical (i.e. mean) sleep and sleep regularity were obtained at each time point. Multilevel growth curves were modeled. RESULTS: Overall, the sleep-wake cycle significantly changed between 8 and 12 years. Mean sleep onset, offset and midpoint exhibited an ascending curvilinear growth pattern that shifted later with age, while mean TST decreased linearly. Weekend-weekday differences (social jetlag) for sleep offset and midpoint became more pronounced each year. Weekday TST was longer than weekend TST, though this difference became smaller over time. Finally, intra-individual variability increased over time for all sleep characteristics, with variability in TST ascending curvilinearly. Important between-person and sex differences were also observed. CONCLUSION: This study reveals the marked changes that occur in the sleep of typically developing pre- and early adolescents. We discuss the potential implications of these trajectories.

Association of delayed chronotype with allergic diseases in primary school children.

To investigate the associations of sleep midpoint for both weekdays and weekends, and chronotype, with allergic diseases, specifically asthma, allergic rhinitis, and eczema in primary school children. In this cross-sectional study, we evaluated 10409 children between 7 and 12 years of age (mean 9.21 ± 1.51 years; male 52.2%). Each allergic disease was defined as children with both diagnosed disease and current symptoms, and the reference group was described as children without any allergic symptoms. Sleep durations and mid-sleep times were calculated by reported sleep timing. Chronotype was determined by mid-sleep time on free days corrected for oversleeping. Children with allergies have shorter sleep duration and later sleep preferences. Late weekly sleep midpoints were associated with higher odds of allergies, and the odds were even higher for later weekday midpoints than their weekend counterparts. Regarding chronotype, the more evening chronotype, the higher the odds of allergic rhinitis and eczema. Additionally, effect of weekday late sleep midpoint on allergies was stronger as the participants who slept less (asthma: aOR,1.62, 95 CI%,1.25-2.10, p < .001; allergic rhinitis: aOR,2.12, 95 CI%,1.68-2.67, p < .001; eczema: aOR, 1.94, 95 CI%,1.52-2.48, p < .001). Further, the associations of chronotype with allergic rhinitis were confounded by second-hand smoking exposure. Our study, which finds an association between chronotype and the odds of three allergic diseases, hopes to improve sleep health awareness, especially in the particular population with allergic diseases, and describes the importance of evaluating modifiable behavioral factors, such as sleep habits, as a plausible factor for the prevention and treatment of allergic diseases.

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.

The mediating effect of DNA methylation in the association between maternal sleep during pregnancy and offspring adiposity status: a prospective cohort study.

BACKGROUND: Childhood overweight/obesity is a global public health concern. It is important to identify its early-life risk factors. Maternal poor sleep is common in late pregnancy, and previous studies indicated that poor sleep may influence the offspring's adiposity status. However, very few studies in humans investigated the effect of the different sleep parameters (sleep quantity, quality, and timing) on the offspring's adiposity indicators, and long-term studies are even more scarce. In addition, the underlying mechanism remains unclear. The present study therefore aimed to examine the association between the three maternal sleep dimensions in the late pregnancy and the offspring adiposity indicators and to explore the potential mediating effect of the cord blood DNA methylation in the above association. METHODS: Included participants in the current study were 2211 healthy pregnant women with singleton gestation from the Shanghai Birth Cohort (SBC) and Shanghai Sleep Birth Cohort (SSBC). Maternal nighttime sleep duration, quality, and midpoint (an indicator of circadian rhythm) were assessed by the same instrument in both cohorts during late pregnancy, and the offspring's body mass index (BMI) and subcutaneous fat (SF) were measured at 2 years old. Additionally, in 231 SSBC samples, the genome-wide DNA methylation levels were measured using the Illumina Infinium Methylation EPIC BeadChip. The multivariate linear regression was used to determine the associations between the maternal sleep parameters and the offspring adiposity indicators. The epigenome-wide association study was conducted to identify the maternal sleep-related CpG sites. The mediation analysis was performed to evaluate the potential intermediate role of DNA methylation in the association between maternal sleep and offspring adiposity indicators. RESULTS: The mean maternal nighttime sleep duration and the sleep midpoint for combined cohorts were 9.24 ± 1.13 h and 3.02 ± 0.82, respectively, and 24.5% of pregnant women experienced poor sleep quality in late pregnancy. After adjusting for the covariates, the maternal later sleep midpoint was associated with the increased SF in offspring (Coef. = 0.62, 95% CI 0.37-0.87, p < 0.001) at 2 years old. However, no significant associations of the nighttime sleep duration or sleep quality with the offspring adiposity indicators were found. In the SSBC sample, 45 differential methylated probes (DMPs) were associated with the maternal sleep midpoint, and then, we observed 10 and 3 DMPs that were also associated with the offspring's SF and BMI at 2 years, of which cg04351668 (MARCH9) and cg12232388 significantly mediated the relationship of sleep midpoint and SF and cg12232388 and cg12225226 mediated the sleep midpoint-BMI association, respectively. CONCLUSIONS: Maternal later sleep timing in late pregnancy was associated with higher childhood adiposity in the offspring. Cord blood DNA methylation may play a mediation role in that relationship.

Genetic variants for morningness in relation to habitual sleep-wake behavior and diurnal preference in a population-based sample of 17,243 adults.

OBJECTIVE: Associations of eveningness with health hazards benefit from analyzing to what extent the polygenic score for morningness correlates with the assessments of the behavioral trait of morningness-eveningness and chronotype. METHODS: With a population-based sample of 17,243 Finnish adults, aged 25-74 years, this study examines the associations of four feasible assessment methods of chronotype, a) biological the genetic liability based on the polygenic score for morningness (PGSmorn), b) the widely-used single item for self-assessed morningness/eveningness (MEQi19) of the original Morningness-Eveningness Questionnaire (MEQ), c) the behavioral trait of morningness-eveningness as assessed with the score on the shortened version (sMEQ) of the original MEQ, and d) the phase of entrainment as assessed with the habitual midpoint of sleep based on the self-reported sleep-wake schedule during weekend (Sleepmid-wknd) as well as the sleep debt corrected midpoint of sleep (Sleepmid-corr). RESULTS: All self-report measures correlated with each other, but very weakly with the PGSmorn, which explained 1-2% of the variation in diurnal preference or habitual sleep-wake schedule. The influence of age was greater on Sleepmid-wknd and Sleepmid-corr than on the sMEQ or MEQi19, indicating that the diurnal preference might be a more stable indicator for morningness-eveningness than the sleep-wake schedule. Analyses of the discrepancies between sMEQ and MEQi19 indicated that eveningness can be over-estimated when relying on only the single-item self-assessment. CONCLUSIONS: The current polygenic score for morningness explains only a small proportion of the variation in diurnal preference or habitual sleep-wake schedule. The molecular genetic basis for morningness-eveningness needs further elucidation.

Sleeping Late Increases the Risk of Myocardial Infarction in the Middle-Aged and Older Populations.

Objective: Sleep has a significant influence on the incidence of myocardial infarction (MI). The purpose of this study was to investigate the association between sleep timing including bedtime, wake-up time and sleep midpoint, and the incidence of MI. Methods: A total of 4,576 patients (2,065 men, 2,511 women; age 63.4 ± 11.0 years) were selected from the Sleep Heart Health Study. Sleep timings on weekdays and weekends were recorded or calculated based on the sleep habits questionnaire completed by the participants at baseline. Bedtime was divided into 10:00 PM and before, 10:01 PM-11:00 PM, 11:01 PM-12:00 AM, and later than 12:00 AM. Cox proportional hazards regression analysis was used to examine the relationship between sleep timings and MI. Results: Participants with a weekday bedtime later than 12:00 AM, between 11:01 PM-12:00 AM, and 10:00 PM or before had a higher incidence of MI than those with a bedtime between 10:01 PM and 11:00 PM (9.2% vs. 7.0% vs. 6.9% vs. 5.1%, respectively; P = 0.008). Multivariable Cox regression analysis showed that sleeping on weekdays later than 12:00 AM was associated with an increased risk of incident MI after adjusting for potential covariates (hazard ratio, 1.628; 95% confidence interval, 1.092-2.427; P = 0.017). However, there was no significant association between late bedtime on weekends and MI. In addition, no significant association of late wake-up time and delayed sleep midpoint on both weekdays and weekends with the incidence of MI was observed. Conclusion: Sleeping late on weekday (>12:00 AM) independently increased the risk of MI. This finding emphasizes the importance of a proper bedtime for the maintenance of the health of the cardiovascular system.

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

OBJECTIVE: Adolescence 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. METHODS: Our 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). RESULTS: PA 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). CONCLUSIONS: Findings 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.

Chronotype in very low birth weight adults - a sibling study.

Chronotype is the temporal preference for activity and sleep during the 24 h day and is linked to mental and physical health, quality of life, and mortality. Later chronotypes, so-called "night owls", consistently display poorer health outcomes than "larks". Previous studies have suggested that preterm birth (<37 weeks of gestation) is associated with an earlier chronotype in children, adolescents, and young adults, but studies beyond this age are absent. Our aim was to determine if adults born preterm at very low birth weight (VLBW, ≤1500 g) display different chronotypes than their siblings. We studied VLBW adults, aged 29.9 years (SD 2.8), matched with same-sex term-born siblings as controls. A total of 123 participants, consisting of 53 sibling pairs and 17 unmatched participants, provided actigraphy-derived data on the timing, duration, and quality of sleep from 1640 nights (mean 13.3 per participant, SD 2.7). Mixed effects models provided estimates and significance tests. Compared to their siblings, VLBW adults displayed 27 min earlier sleep midpoint during free days (95% CI: 3 to 51 min, p =.029). This was also reflected in the timing of falling asleep, waking up, and sleep-debt corrected sleep midpoint. The findings were emphasized in VLBW participants born small for gestational age. VLBW adults displayed an earlier chronotype than their siblings still at age 30, which suggests that the earlier chronotype is an enduring individual trait not explained by shared family factors. This preference could provide protection from risks associated with preterm birth. ABBREVIATIONS: AGA: Appropriate for gestational age; ELBW: Extremely low birth weight, ≤ 1000 grams; FMBR: Finnish Medical Birth Registry; HeSVA: Helsinki Study of Very low birth weight Adults; MSFsc: Midsleep on free days, corrected for sleep debt; SGA: Small for gestational age, ≤ -2 SD; VLBW: Very low birth weight, ≤ 1500 grams; WASO: Wake after sleep onset.