The effects of social jetlag and sleep variability on sleepiness in a population-based study: The mediating role of sleep debt

Sleepiness is a multicausal condition, and previous research has highlighted associations between this symptom and the circadian timing system, specifically concerning social jetlag and sleep variability. Recent inquiries have shown that the effects of social jetlag on sleepiness can be confounded with the consequences of sleep debt. In light of the current evidence, we aimed to assess the effects of social jetlag and sleep variability on sleepiness and the potential mediating role of sleep debt. We used data from the EPISONO study, a cross-sectional population-based study with a sample size of 1042 participants, representative of the city of Sao Paulo, Brazil. Participants completed the UNIFESP Sleep Questionnaire (self-reported bedtime and get-up time) and the Epworth Sleepiness Scale (subjective daytime sleepiness). Subsequently, sleep-corrected mid-sleep time (chronotype), total sleep time, social jetlag (absolute difference between the mid-sleep time on workdays and mid-sleep time on free days), sleep variability (standard deviation of mid-sleep time), and sleep debt (difference between total sleep time on workdays and free days) were calculated. Generalised linear models were used to test whether social jetlag and sleep variability affected sleepiness. Mediation models were used to determine if any observed significant effects were mediated by sleep debt. The prevalence of social jetlag was 23% for >1 h and 12% for >2 h. The mean sleep variability was 41 ± 30 min. Social jetlag had a significant effect on the Epworth Sleepiness Scale scores. This association was no longer statistically significant after controlling for age, sex, body mass index, work schedule, and chronotype. A significant indirect effect of social jetlag on sleep debt and subsequently on the Epworth Sleepiness Scale scores was found. No effect of sleep variability on sleepiness could be identified. In conclusion, the association between social jetlag and sleepiness was mediated by sleep debt but was not independent of demographic, work, and chronotype variables. This study provides new evidence on the importance of circadian misalignment and sleep debt for sleep health on a population level.

Patterns of Sleep Duration and Metabolic Biomarkers Across the Menstrual Cycle

CONTEXT

Along the menstrual cycle, associations between inconsistent sleep duration and levels of metabolic biomarkers are uncertain and could involve fluctuations in estrogen concentrations.

OBJECTIVE

To examine associations between patterns of sleep duration and metabolic biomarkers across two menstrual cycles within a cohort of premenopausal women.

METHODS

The BioCycle Study was conducted in New York between 2005-2007, enrolling 259 premenopausal women over two menstrual cycles. This micro-longitudinal cohort study involved intensive data collection including daily sleep diaries and biomarker assessments of leptin, insulin, and glucose at 16 key points timed to menstrual cycle phases. We considered dynamic sleep duration, as hours slept one night or as mean hours slept during the two nights prior to each biomarker assessment. Variability in habitual sleep duration, i.e., reported daily sleep duration, summarized across both menstrual cycles. Variation in habitual sleep duration was computed using L-moments, a robust version of dispersion, skewness, and kurtosis. To examine associations between patterns of sleep duration and metabolic biomarkers, we fitted a series of linear mixed models with random intercepts and inverse probability weighting. These models were adjusted for potential demographic, lifestyle, health confounders, and menstrual cycle phase.

RESULTS

Sleep duration one night or two nights prior to clinic visits were not associated with metabolic biomarker measures we assessed. However, overall variability (dispersion) in habitual sleep duration was associated with lower mean insulin HOMA-IR levels, but not glucose. Moreover, extreme short or long bouts of sleep duration was associated with higher mean levels of leptin, insulin, and HOMA-IR.

CONCLUSIONS

These data suggest that variation in habitual sleep duration along the menstrual cycle may be associated with metabolic function.

Actigraphic sleep dimensions and associations with academic functioning among adolescents

STUDY OBJECTIVES

There is mixed evidence regarding associations of sleep duration with academic functioning in adolescents and a lack of research on other sleep dimensions, particularly using objective sleep measures. We examined associations of multiple actigraphic sleep dimensions with academic functioning among adolescents.

METHODS

Data were from the sleep sub-study of the age 15 wave of the Future of Families and Child Wellbeing Study (n=774-782), a national, diverse sample of teens. Adolescents wore wrist-actigraphs for ~1 week and completed a survey reporting grades and school-related problems. Regression models assessed whether average sleep duration, timing, maintenance efficiency, and SD-variability were associated with self-reported academic functioning in cross-sectional analyses adjusted for demographic characteristics, depressive symptoms, and anxious symptoms.

RESULTS

Later sleep timing (hrs) and greater sleep variability (SD-hrs) were associated with poorer academic outcomes, including sleep onset variability with higher odds of receiving a D or lower (OR=1.29), sleep onset (β=-.07), sleep offset (β=-.08), and sleep duration variability (β=-.08) with fewer A grades, sleep offset with lower GPA (β=-.07), sleep offset (OR=1.11), sleep duration variability (OR=1.31), and sleep onset variability (OR=1.42) with higher odds of being suspended or expelled in the past two years, and sleep duration variability with greater trouble at school (β=.13). Sleep duration, sleep maintenance efficiency, and sleep regularity index were not associated with academic functioning.

CONCLUSION

Later sleep timing and greater sleep variability are risk factors for certain academic problems among adolescents. Promoting sufficient, regular sleep timing across the week may improve adolescent academic functioning.

Sleep Variability, Sleep Irregularity, and Nighttime Blood Pressure Dipping

BACKGROUND

Circadian rhythm regulates many important biological functions in humans. The goal of this study is to explore the impact of day-to-day deviations in the sleep-wake cycle on nighttime blood pressure (BP) dipping and further examine whether the ethnic difference in day-to-day deviations in sleep patterns can explain the ethnic difference in nighttime BP dipping.

METHODS

Twenty-four-hour ambulatory BP monitoring and 7-day accelerometer data were obtained from 365 adult participants (age range, 18.7-50.1 years; 52.6% Black participants and 47.3% European Americans; 64.1% females). Systolic BP dipping level was used to represent nighttime BP dipping. The SD of sleep duration was calculated as the index of sleep variability, and the SD of sleep midpoint was calculated as the index of sleep irregularity.

RESULTS

A 1-hour increase in the SD of sleep midpoint was associated with a 1.16% decrease in nighttime BP dipping (P<0.001). A 1-hour increase in the SD of sleep duration was associated with a 1.39% decrease in nighttime BP dipping (P=0.017). The ethnic difference in the SD of sleep midpoint can explain 29.2% of the ethnicity difference in BP dipping (P=0.008).

CONCLUSIONS

Sleep variability and sleep irregularity are associated with blunted BP dipping in the general population. In addition, data from the present investigation also demonstrate that the ethnic difference in sleep irregularity could partly explain the ethnic difference in BP dipping, an important finding that may help reduce the health disparity between Black participants and European Americans.

Variability in Sleep Duration and Biomarkers of Cardiovascular Disease Across the Menstrual Cycle

Variability in sleep duration and cardiovascular health have been infrequently investigated, particularly among reproductive-age women. We examined these associations across the menstrual cycle among a cohort of 250 healthy premenopausal women, aged 18-44 years. The BioCycle study (New York, 2005-2007) collected cardiovascular biomarkers (serum high- and low-density lipoprotein (HDL, LDL), total cholesterol, triglycerides, and C-reactive protein (CRP)) at key time points along the menstrual cycle (follicular, ovulatory, and luteal phases). Women also recorded sleep duration in daily diaries. From these data, we computed L-moments, robust versions of location, dispersion, skewness, and kurtosis. We fitted linear mixed models with random intercepts and inverse probability weighting to estimate associations between sleep variability and cardiovascular biomarkers, accounting for demographic, lifestyle, health, and reproductive factors. Sleep dispersion (any deviation from mean duration) was associated with lower mean LDL for nonshift workers and non-White women. Skewed sleep duration was associated with higher mean CRP and lower mean total cholesterol. Sleep durations with extreme short and long bouts (kurtosis) were associated with a lower mean HDL, but not mean CRP, LDL, or triglycerides. Sleep duration modified associations between sleep dispersion and LDL, HDL, and total cholesterol. Even in young and healthy women, sleep duration variability could influence cardiovascular health.

Interrupted lullabies: the association between menopausal symptoms and sleep variability in peri- and post-menopausal women

Poor sleep is a reality for many midlife women experiencing menopause. Although much empirical attention has been allocated toward ameliorating vasomotor symptoms and related consequences, less focus has been given toward sleep, specifically sleep variability, in menopausal women. The present study aimed to determine the association between menopausal symptoms and night-to-night sleep variability among peri- and post-menopausal women. Participants were 220 menopausal women (42.3 percent peri-menopausal, 57.7 percent post-menopausal) aged 40 to 64 from the United States recruited via Prolific, and online platform. The current study conducted secondary analyses on data collected as part of a larger investigation on midlife women from the United States. A structural equation model assessed associations between a latent menopausal symptom construct, composed of several Women's Health Questionnaire domains, and a latent sleep variability construct, composed of sleep diary indices. Menopausal symptoms were associated with latent sleep variability (β = 0.49, p < .05); greater experience of menopausal symptoms was associated with more night-to-night sleep variability (medium effect size). Waking after sleep onset (WASO) was the sole significant indicator of the latent sleep factor. The findings highlight the importance of menopausal symptoms for sleep variability, specifically wakefulness. As such, wakefulness may be an important target for sleep interventions for menopausal women. The findings further suggest a need for more research and interventions targeted toward understanding and ameliorating the impact of menopausal symptoms on night-to-night wakefulness overall.

Variability in Sleep Timing and Dietary Intake: A Scoping Review of the Literature

The objective of this scoping review was to summarize previous studies which examined the effect of day-to-day variability in sleep timing and social jetlag (SJL) on dietary intake. A systematic literature search was conducted in PubMed, Embase, and Clarivate Analytics Web of Science and we identified 22 records. No difference in caloric and macronutrient intake between SJL groups was observed in studies that enrolled healthy young adults. However, studies that enrolled participants with obesity and obesity-related chronic conditions reported a higher caloric intake and a higher intake of carbohydrates, total fat, saturated fats, and cholesterol in participants with SJL than in those without. Most studies reported a lower quality of diet, a delayed mealtime, and eating jetlag in participants with SJL vs. those without SJL. No correlation of day-to-day variability in sleep timing with average caloric intake was observed, but bed-time variability was negatively associated with diet quality. Methodological issues have been identified in sources assessed including study design, power calculation, population enrolled, and tools/metrics used for sleep timing variability assessment. Future well powered longitudinal studies, with clear protocols, standardized metrics, including all age groups from general population are needed to clarify the dietary intake consequences of variability in sleep timing.

Minimum number of nights for reliable estimation of habitual sleep using a consumer sleep tracker

Study Objectives

To determine the minimum number of nights required to reliably estimate weekly and monthly mean sleep duration and sleep variability measures from a consumer sleep technology (CST) device (Fitbit).

Methods

Data comprised 107 144 nights from 1041 working adults aged 21-40 years. Intraclass correlation (ICC) analyses were conducted on both weekly and monthly time windows to determine the number of nights required to achieve ICC values of 0.60 and 0.80, corresponding to "good" and "very good" reliability thresholds. These minimum numbers were then validated on data collected 1-month and 1-year later.

Results

Minimally, 3 and 5 nights were required to obtain "good" and "very good" mean weekly total sleep time (TST) estimates, while 5 and 10 nights were required for monthly TST estimates. For weekday-only estimates, 2 and 3 nights were sufficient for weekly time windows while 3 and 7 nights sufficed for monthly time windows. Weekend-only estimates of monthly TST required 3 and 5 nights. TST variability required 5 and 6 nights for weekly time windows, and 11 and 18 nights for monthly time windows. Weekday-only weekly variability required 4 nights for both "good" and "very good" estimates while monthly variability required 9 and 14 nights. Weekend-only estimates of monthly variability required 5 and 7 nights. Error estimates made using data collected 1-month and 1-year later with these parameters were comparable to those associated with the original dataset.

Conclusions

Studies should consider the metric, measurement window of interest, and desired reliability threshold to decide on the minimum number of nights required to assess habitual sleep using CST devices.

Regularity and Timing of Sleep Patterns and Behavioral Health Among Adolescents

OBJECTIVE

Sleep is vital to supporting adolescent behavioral health and functioning; however, sleep disturbances remain under-recognized and undertreated in many health care settings. One barrier is the complexity of sleep, which makes it difficult for providers to determine which aspects-beyond sleep duration-may be most important to assess and treat to support adolescent health. This study examined associations between 2 sleep indices (regularity and timing) and adolescent behavioral health and functioning over and above the impact of shortened/fragmented sleep.

METHOD

Eighty-nine adolescents recruited from the community (mean age = 14.04, 45% female participants) completed 7 days/nights of actigraphy and, along with a parent/guardian, reported on behavioral health (internalizing and externalizing symptoms) and psychosocial functioning. Stepwise linear regressions examined associations between sleep timing and regularity and behavioral/functional outcomes after accounting for shortened/fragmented sleep.

RESULTS

Delayed sleep timing was associated with greater self-reported internalizing (F[6,82] = 11.57, p = 0.001) and externalizing (F[6,82] = 11.12, p = 0.001) symptoms after accounting for shortened/fragmented sleep. Irregular sleep was associated with greater self-reported and parent-reported externalizing symptoms (self: F[7,81] = 6.55, p = 0.01; parent: F[7,80] = 6.20, p = 0.01) and lower psychosocial functioning (self: F[7,81] = 6.03, p = 0.02; parent: F[7,78] = 3.99, p < 0.05) after accounting for both shortened/fragmented sleep and delayed sleep timing.

CONCLUSION

Sleep regularity and timing may be critical for understanding the risk of poor behavioral health and functional deficits among adolescents and as prevention and intervention targets. Future work should focus on developing and evaluating convenient, low-cost, and effective methods for addressing delayed and/or irregular adolescent sleep patterns in real-world health care settings.

Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing

Many people are concerned about whether they are getting “enough” sleep, and if they can “sleep too much.” These concerns can be approached scientifically using experiments probing long-term (i.e., multi-night) sleep homeostatic processes, since homeostatic processes move the system toward its physiological setpoint (i.e., between “not enough” and “too much”). We analyzed sleep data from two human studies with sleep opportunities much longer than people usually stay in bed (i.e., conditions in which sleep homeostatic responses could be documented): sleep opportunities were 14–16 h per day for 3–28 days. Across the nights of the extended sleep opportunities, total sleep duration, Rapid Eye Movement (REM) sleep duration and non-REM sleep durations decreased and sleep latency increased. Multiple nights were required to reach approximately steady-state values. These results suggest a multi-day homeostatic sleep process responding to self-selected insufficient sleep duration prior to the study. Once steady state-values were reached, there were large night-to-night variations in total sleep time and other sleep metrics. Our results therefore answer these concerns about sleep amount and are important for understanding the basic physiology of sleep and for two sleep-related topics: (i) the inter-individual and intra-individual variability are relevant to understanding “normal” sleep patterns and for people with insomnia and (ii) the multiple nights of sleep required for recovery from insufficient sleep from self-selected sleep loss is important for public health and other efforts for reducing the adverse effects of sleep loss on multiple areas of physiology.

Longitudinal associations between adolescents' sleep and adjustment: Respiratory sinus arrhythmia as a moderator

Sleep and autonomic nervous system functioning are important bioregulatory systems. Poor sleep and low baseline respiratory sinus arrhythmia (RSA), a measure of parasympathetic nervous system activity, are associated with externalizing behaviors and depressive symptoms in youth. Rarely, however, have measures of these systems been examined conjointly. The present study examined baseline RSA (RSA-B) as a moderator of longitudinal relations between adolescent sleep and adjustment. Participants were 256 adolescents (52% girls, 66% White/European American, 34% Black/African American) from small towns and surrounding rural communities in the southeastern United States. Sleep (minutes, efficiency, variability in minutes and efficiency) was assessed at age 15 via actigraphs across seven nights. RSA-B was derived from electrocardiogram data collected at rest. Adolescents self-reported externalizing problems and depressive symptoms at ages 15 and 17. Controlling for age 15 adjustment, findings generally demonstrated that sleep predicted age 17 adjustment particularly at higher (rather than lower) levels of RSA-B, such that adolescents with good sleep (more minutes and lower variability) and high RSA-B were at lowest risk for maladjustment. The results highlight the value of examining multiple bioregulatory processes conjointly and suggest that promoting good sleep habits and regulation of physiological arousal should support adolescent adjustment.

Too Jittery to Sleep? Temporal Associations of Actigraphic Sleep and Caffeine in Adolescents

Caffeine consumption has been linked to poor sleep health in adolescents, but it is unknown whether poor sleep predicts caffeine consumption, and/or whether caffeine consumption predicts poor sleep, particularly when sleep is measured objectively. Data were collected from a micro-longitudinal sub-study of the age 15 wave of the Fragile Families and Child Wellbeing Study (n = 589). Adolescents wore an actigraphy device and completed daily surveys for ~1 week. Daily surveys assessed subjective sleep quality and caffeinated beverage consumption (0 = no caffeine, 1 = any caffeine). Separate mixed models assessed whether actigraphy-measured sleep duration, timing, maintenance efficiency, and subjective quality predicted next-day caffeinated beverage consumption within and between adolescents. Variability (standard deviation) of sleep duration and timing, sleep regularity index, and social jetlag were tested as additional between-person predictors. Lagged models tested whether daily caffeinated beverage consumption predicted sleep that night (n = 458). Adolescents with more variable sleep duration and midpoint had higher average odds of consuming caffeinated beverages compared to others. After adolescents consumed ≥1 caffeinated beverage, they had later sleep onset that night and wake time the next morning than usual versus when they did not consume caffeine. Curbing caffeinated beverage consumption may aid in the maintenance of regular sleep schedules and advance sleep timing in adolescents.

Association of job strain with accelerometer-based sleep duration and timing of sleep among older employees

Job strain has been associated with poor sleep quality and could lead to changes in duration and timing of sleep as well. This study examined the association of job strain with sleep duration, bedtimes and awakening times among public sector employees close to their retirement age. Differences in these sleep parameters between workdays and free days across job strain groups were examined. Duration and timing of sleep were measured repeatedly with accelerometers among 466 public sector employees in Finland (mean age 63 years, 86% women), who contributed to 759 measurements in total. Job demands (low/high) and control (low/high) measured by self-reports and job exposure matrix were used to identify low strain (low demand, high control), passive (low, low), active (high, high) and high strain (high, low) jobs. No differences in sleep duration were observed on workdays, whereas on free days those in the high strain group had longer sleep duration than those in the low strain and passive job groups. The high strain group also extended their sleep from workdays to free days more, the extension being on average 59 min (95% CI 42 min-75 min) when adjusted for several sociodemographic, work and health factors. This extension of sleep duration resulted mostly from a greater delay of awakening times from workdays to free days. Psychosocial work factors, such as job strain, need to be considered when promoting sufficient sleep duration among older employees, as those with job strain may have a greater need for recovery and sleep.

Sleep quantity and variability during the first semester at university: implications for well-being and academic performance

Research has demonstrated the importance of sleep quality for university students, although work is limited with respect to how sleep during the first semester of school impacts well-being and academic outcomes. The current study sought to examine the role of sleep quantity and variability over the first semester of university on GPA and happiness. Students (n = 97) from a first-semester psychology course completed weekly assessments of sleep and well-being (happiness and anxiety) for 15 weeks, and they gave permission for researchers to collect their GPA and SAT data from the registrar. Average weekly sleep quantity was associated with greater weekly happiness and less anxiety. Weekly sleep variability was associated with lower happiness and more anxiety. Even when accounting for sleep quantity and initial start-of-semester measures, sleep variability predicted worse GPA and happiness for students at the end-of-semester. In summary, sleep consistency may be an important target for health professionals working within the university setting. This study contributes to the literature on the importance not only of sleep but also of sleep consistency, during a major life transition.

Gender differences in nighttime sleep patterns and variability across the adult lifespan: a global-scale wearables study

STUDY OBJECTIVES

Previous research on sleep patterns across the lifespan have largely been limited to self-report measures and constrained to certain geographic regions. Using a global sleep dataset of in situ observations from wearable activity trackers, we examine how sleep duration, timing, misalignment, and variability develop with age and vary by gender and BMI for nonshift workers.

METHODS

We analyze 11.14 million nights from 69,650 adult nonshift workers aged 19-67 from 47 countries. We use mixed effects models to examine age-related trends in naturalistic sleep patterns and assess gender and BMI differences in these trends while controlling for user and country-level variation.

RESULTS

Our results confirm that sleep duration decreases, the prevalence of nighttime awakenings increases, while sleep onset and offset advance to become earlier with age. Although men tend to sleep less than women across the lifespan, nighttime awakenings are more prevalent for women, with the greatest disparity found from early to middle adulthood, a life stage associated with child-rearing. Sleep onset and duration variability are nearly fixed across the lifespan with higher values on weekends than weekdays. Sleep offset variability declines relatively rapidly through early adulthood until age 35-39, then plateaus on weekdays, but continues to decrease on weekends. The weekend-weekday contrast in sleep patterns changes as people age with small to negligible differences between genders.

CONCLUSIONS

A massive dataset generated by pervasive consumer wearable devices confirms age-related changes in sleep and affirms that there are both persistent and life-stage dependent differences in sleep patterns between genders.

Sleep among Youth with Severely Disabling Chronic Pain: Before, during, and after Inpatient Intensive Interdisciplinary Pain Treatment

Poor sleep is commonly reported in pediatric chronic pain. There are signals that intensive interdisciplinary pain treatments (IIPT) may inadvertently improve objective sleep, but this claim cannot be substantiated without baseline sleep data prior to IIPT. This study followed the objective sleep/wake patterns (e.g., duration, quality, timing, consistency) of pediatric patients with severely functionally disabling chronic pain before, during, and after inpatient IIPT (the Functional Independence Restoration Program-"FIRST Program"), alongside a similarly-disabled chronic pain Comparison Group. The final sample included N = 10 FIRST Patients and N = 9 Comparison Group patients. At baseline, the whole sample showed healthy sleep duration (~9 h), average sleep efficiency <90%, late sleep onset and offset (mean = 11:56 p.m.-8:50 a.m.), and highly inconsistent sleep schedules night to night. During IIPT, FIRST Patients maintained healthy sleep durations, moved sleep schedules 2 h earlier, and decreased timing and duration variability by >60 min while the Comparison Group maintained similar sleep to baseline. At follow up (1-2 months later), FIRST Patients' sleep schedules shifted later but were still less variable than at baseline. Results point to the malleability of sleep/wake patterns within treatment contexts with strict environmental control but suggest that these gains may be difficult for youth with chronic pain to maintain in the home environment.

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

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.

Sleep, self-management, neurocognitive function, and glycemia in emerging adults with Type 1 diabetes mellitus: A research protocol

Type 1 Diabetes (T1D) affects 1.6 million Americans, and only 14% of emerging adults ages 18-25 years achieve targets for glycemic control (A1C < 7.0%). Sleep deficiency, including habitual short sleep duration (<6.5 hr total sleep time and high within-person variability in total sleep time), is associated with poorer glycemic control. Emerging adults with T1D have a more pronounced sleep extension on weekends compared with matched controls, consistent with sleep deficiency; however, associations among sleep variability and glycemic control have not been explored in this population. Sleep deficiency may affect the complex higher-order neurocognitive functioning needed for successful diabetes self-management (DSM). We report the protocol for an ongoing study designed to characterize sleep and the associations among sleep deficiency, neurocognitive function, DSM, diabetes quality of life, and glycemia among a sample of 40 emerging adults with T1D. We monitor sleep via wrist-worn actigraphy and glucose via continuous glucose monitoring concurrently over 14 days. We are collecting data on self-report and objective sleep, a 10-min psychomotor vigilance test on a PVT-192 device, a 3-min Trail Making Test on paper, and questionnaires, including twice-daily Pittsburgh sleep diaries using Research Electronic Data Capture (REDCap)^TM . Results from this study will be used to support the development and testing of the efficacy of a tailored sleep self-management intervention that may improve total sleep time, sleep variability, neurocognitive function, DSM, glycemic control, and glucose variability among emerging adults with T1D.

Effect of Cognitive Behavioral Therapy for Insomnia on Insomnia Symptoms for Individuals With Type 2 Diabetes: Protocol for a Pilot Randomized Controlled Trial

Background

Insomnia symptoms are a common form of sleep difficulty among people with type 2 diabetes (T2D) affecting sleep quality and health outcomes. Several interventional approaches have been used to improve sleep outcomes in people with T2D. Nonpharmacological approaches, such as cognitive behavioral therapy for insomnia (CBT-I), show promising results regarding safety and sustainability of improvements, although CBT-I has not been examined in people with T2D. Promoting sleep for people with insomnia and T2D could improve insomnia severity and diabetes outcomes.

Objective

The objective of this study is to establish a protocol for a pilot randomized controlled trial (RCT) to examine the effect of 6 sessions of CBT-I on insomnia severity (primary outcome), sleep variability, and other health-related outcomes in individuals with T2D and insomnia symptoms.

Methods

This RCT will use random mixed block size randomization with stratification to assign 28 participants with T2D and insomnia symptoms to either a CBT-I group or a health education group. Outcomes including insomnia severity; sleep variability; diabetes self-care behavior (DSCB); glycemic control (A_1c); glucose level; sleep quality; daytime sleepiness; and symptoms of depression, anxiety, and pain will be gathered before and after the 6-week intervention. Chi-square and independent t tests will be used to test for between-group differences at baseline. Independent t tests will be used to examine the effect of the CBT-I intervention on change score means for insomnia severity, sleep variability, DSCB, A_1c, fatigue, sleep quality, daytime sleepiness, and severity of depression, anxiety, and pain. For all analyses, alpha level will be set at .05.

Results

This study recruitment began in February 2019 and was completed in September 2019.

Conclusions

The intervention, including 6 sessions of CBT-I, will provide insight about its effect in improving insomnia symptoms, sleep variability, fatigue, and diabetes-related health outcomes in people with T2D and those with insomnia symptoms when compared with control.

Trial Registration

ClinicalTrials.gov NCT03713996; https://clinicaltrials.gov/ct2/show/NCT03713996

International Registered Report Identifier (IRRID)

DERR1-10.2196/14647

Sleep duration, sleep variability, and impairments of visual attention

Attentional networks are sensitive to sleep deprivation. However, variation in attentional performance as a function of normal sleep parameters is understudied. We examined whether attentional performance is influenced by (a) individual differences in sleep duration, (b) sleep duration variability, and/or (c) their interaction. A total of 57 healthy participants (61.4% female, M_age = 32.37 years, SD = 8.68) completed questionnaires, wore wrist actigraphy for 1 week, and subsequently completed the attention network test. Sleep duration and sleep duration variability did not predict orienting score, executive control score, or error rates. Sleep duration variability appeared to moderate the association between sleep duration with overall reaction time (β = -.34, t = -2.13, p = .04) and alerting scores (β = .43, t = 2.94, p = .01), though further inspection of the data suggested that these were spurious findings. Time of testing was a significant predictor of alerting score (β = .35, t = 2.96, p = .01), chronotype of orienting (β = .31, t = 2.28, p = .03), and age of overall reaction time (β = .35, t = 2.70, p = .01). Our results highlight the importance of examining the associations between variations in sleep-wake patterns and attentional networks in samples with greater variation in sleep, as well as the importance of rigorously teasing apart mechanisms of the sleep homeostat from those related to the circadian rhythm in studies examining cognition.

The cross-sectional and prospective associations between sleep characteristics and adiposity in toddlers: Results from the GET UP! Study

BACKGROUND

The associations between sleep characteristics and adiposity in children under three years are not fully understood yet.

OBJECTIVE

The objective of the study is to examine the cross-sectional and prospective associations between sleep characteristics and adiposity in toddlers over a 12-month period.

METHODS

Participants were 202 toddlers from the GET-UP!

STUDY

Sleep duration, sleep timing, and sleep variability were assessed using 24-hour accelerometry for seven consecutive days. Height and weight were measured, and BMI z scores were calculated. Linear mixed models were performed to examine the cross-sectional and prospective associations between sleep characteristics and adiposity, with adjustments for clustering effects and demographic factors.

RESULTS

Total sleep duration was negatively associated with higher adiposity cross-sectionally (B = -0.12; 95% CI: -0.23, -0.01; .033) but not prospectively (B = 0.01; 95% CI: -0.13, 0.10; .843). Nap duration was prospectively associated with higher levels of adiposity (B = 0.41; 95% CI: 0.14, 0.68; .003). Sleep variability and sleep timing were not associated with concurrent or subsequent adiposity.

CONCLUSION

Although sleep duration is an important factor associated with obesity in toddlerhood, the potential effects of different types of sleep duration may vary. While longer total sleep duration may protect children from increasing adiposity, longer nap duration seems to be risk factor. As evidence in this age group is scarce, more research is needed to confirm this finding.

Comparison of Sleep Patterns in Vietnam Veterans With and Without Posttraumatic Stress Disorder Using Wrist Actigraphy

STUDY OBJECTIVES

Disturbed sleep is a hallmark feature of posttraumatic stress disorder (PTSD). However, few studies have examined sleep objectively in individuals with PTSD compared to trauma-exposed controls. This study used wrist actigraphy to measure and compare sleep patterns in trauma-exposed Australian Vietnam veterans (VV) with and without PTSD.

METHODS

Trauma-exposed Australian VV with and without PTSD were recruited from the PTSD Initiative. VV wore wrist accelerometers over 14 days and completed daily sleep diaries. Sleep parameters were compared between groups including sleep latency (SL), time in bed (TIB), total sleep time (TST), wake after sleep onset (WASO), and movement index (MI). Night-to-night and overall within-individual variability were assessed by root mean squared successive differences and comparison of individual standard deviations. Correlations between sleep diary (self-reported) and wrist actigraphy (objective) variables were also assessed.

RESULTS

A total of 40 male VV (20 with PTSD) participated in the study. We found no difference in sleep patterns determined by wrist actigraphy between groups with the exception of reduced SL in VV with PTSD (3.9 ± 0.9 versus 4.9 ± 1.4 minutes, P < .05). Overall within-individual variability was significantly greater in VV with PTSD for TIB, TST, WASO, and MI. Self-reported and objective TST and WASO were more strongly correlated in VV without PTSD than those with PTSD.

CONCLUSIONS

Although there were no significant differences in sleep parameters, VV with PTSD had increased within-individual overall sleep variability and reduced correlation between self-reported and objective sleep parameters compared to trauma-exposed controls. Further evaluation of extended sleep patterns by actigraphy in VV with PTSD is warranted.

The coupling of short sleep duration and high sleep need predicts riskier decision making

Objective: To examine how risk-related decision making might be associated with habitual sleep variables, including sleep variability, sleep duration and perceived sleep need in young adults cross-sectionally and longitudinally. Design: 166 participants completed a 7-day protocol with sleep and risk-related decision-making measures at baseline (T1) and 12 months later (T2). Results: Habitual short sleep duration (averaging < 6 h nightly) was identified in 11.0% in our sample. After controlling for baseline demographic factors and risk-taking measures, self-reported sleep need at T1 interacted with habitual short sleep in predicting risk taking at follow-up (F_8,139=9.575, adjusted R²=.431, p<.001). T1 greater perceived sleep need predicted more risk taking among short sleepers, but decreased risk taking among normal sleepers at T2. Variable sleep timing was cross-sectionally correlated with making more Risky choices at baseline and fewer Safe choices after loss at follow up. Conclusions: Young adults with variable sleep timing and those with short sleep duration coupled with high perceived sleep need were more likely to take risks. The moderating effects of perceived sleep need suggest that individual differences may alter the impact of sleep loss and hence should be measured and accounted for in future studies.

Self-report sleep quality combined with sleep time variability distinguishes differences in fatigue, anxiety, and depression in individuals with multiple sclerosis: A secondary analysis

BACKGROUND

Nearly 70% of individuals with multiple sclerosis report sleep disturbances or poor sleep quality. Sleep disturbances may exacerbate or complicate the management of multiple sclerosis-related symptoms. While sleep variability has been associated with several health outcomes, it is unclear how sleep variability is associated with multiple sclerosis-related symptoms.

OBJECTIVE

The purpose of this study was to determine how total sleep time variability combined with self-reported sleep quality is associated with fatigue, depression, and anxiety in individuals with multiple sclerosis.

METHODS

This study involved a secondary analysis of actigraphy data and questionnaires to assess sleep quality, fatigue, anxiety, and depression.

RESULTS

There were significant differences between the Good Sleepers (good sleep quality/low sleep time variability; n=14) and Bad Sleepers (poor sleep quality/high sleep time variability; n=23) in overall fatigue (p=0.003), cognitive (p=0.002) and psychosocial fatigue (p=0.01) subscales, and in trait anxiety (p=0.007). There were significant differences in state (p=0.004) and trait (p=0.001) anxiety and depression (p=0.002) between the Good Sleepers and Poor Reported Sleepers (poor sleep quality/low sleep time variability; n=24).

CONCLUSION

These results indicate different factors are associated with poor sleep quality in individuals with low versus high total sleep time variability. Considering the factors that are associated with sleep quality and variability may allow for better tailoring of interventions aimed at improving sleep issues or comorbid conditions.

Night-to-Night Sleep Variability in Older Adults With Chronic Insomnia: Mediators and Moderators in a Randomized Controlled Trial of Brief Behavioral Therapy (BBT-I)

STUDY OBJECTIVES

Sleep variability is a clinically significant variable in understanding and treating insomnia in older adults. The current study examined changes in sleep variability in the course of brief behavioral therapy for insomnia (BBT-I) in older adults who had chronic insomnia. Additionally, the current study examined the mediating mechanisms underlying reductions of sleep variability and the moderating effects of baseline sleep variability on treatment responsiveness.

METHODS

Sixty-two elderly participants were randomly assigned to either BBT-I or self-monitoring and attention control (SMAC). Sleep was assessed by sleep diaries and actigraphy from baseline to posttreatment and at 3-month follow-up. Mixed models were used to examine changes in sleep variability (within-person standard deviations of weekly sleep parameters) and the hypothesized mediation and moderation effects.

RESULTS

Variabilities in sleep diary-assessed sleep onset latency (SOL) and actigraphy-assessed total sleep time (TST) significantly decreased in BBT-I compared to SMAC (Pseudo R² = .12, .27; P = .018, .008). These effects were mediated by reductions in bedtime and wake time variability and time in bed. Significant time × group × baseline sleep variability interactions on sleep outcomes indicated that participants who had higher baseline sleep variability were more responsive to BBT-I; their actigraphy-assessed TST, SOL, and sleep efficiency improved to a greater degree (Pseudo R² = .15 to .66; P < .001 to .044).

CONCLUSIONS

BBT-I is effective in reducing sleep variability in older adults who have chronic insomnia. Increased consistency in bedtime and wake time and decreased time in bed mediate reductions of sleep variability. Baseline sleep variability may serve as a marker of high treatment responsiveness to BBT-I.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, Identifier: NCT02967185.

Sleep Patterns and Mental Health Correlates in US Adolescents

OBJECTIVE

To investigate systematically the associations of sleep patterns with a range of mental disorders and other outcomes among a nationally representative sample of US adolescents.

STUDY DESIGN

Using the National Comorbidity Survey Adolescent Supplement, a nationally representative cross-sectional survey of 10 123 US adolescents 13-18 years of age, we assessed associations between adolescent-reported sleep patterns (tertiles of weeknight bedtime, weeknight sleep duration, weekend bedtime delay, and weekend oversleep) and past-year mental disorders based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, smoking, injury, suicidality, and perceived mental and physical health, assessed via direct diagnostic interview.

RESULTS

The average weeknight bedtime was at 22:37 and sleep duration was 7.72 hours. Average weekend bedtime delay was 1.81 hours and average weekend oversleep was 1.17 hours. Later weeknight bedtime, shorter weeknight sleep duration, greater weekend bedtime delay, and both short and long periods of weekend oversleep were associated with increased odds of mood, anxiety, substance use, and behavioral disorders, as well as suicidality, tobacco smoking, and poor perceived mental and physical health. ORs ranged from 1.27 to 2.15. The only outcomes not associated with any sleep patterns were past-year injury and eating disorder.

CONCLUSIONS

Suboptimal sleep patterns were associated with an array of mental disorders and other health-related outcomes among adolescents. Abnormal sleep patterns may serve as markers of prodromal or untreated mental disorders among adolescents, and may provide opportunities for prevention and intervention in mental disorders.

Relationship of Sleep Duration and Regularity with Dietary Intake Among Preschool-Aged Children with Obesity from Low-Income Families

OBJECTIVE

Diet is a modifiable factor associated with pediatric obesity outcomes, but few studies have evaluated the relationships of sleep duration and regularity on dietary intake of young preschool-aged children. The goal of this study was to evaluate whether short sleep duration and irregular sleep timing were associated with greater calorie, carbohydrate and fat consumption among young children with obesity from low-income families.

METHODS

Fifty-one ethnically diverse children aged 2 to 4 years were recruited from the Special Supplemental Nutrition Program for Women, Infants, and Children clinics in a southeast Texas county. Sleep behaviors were parent reported using the Child Sleep Assessment tool. Dietary intake data were obtained by 24-hour recall interviews (2 weekdays and 1 weekend day).

RESULTS

Short sleep duration (<11 hr) was highly prevalent among this cohort of preschool-aged children. Short sleep duration was associated with greater fat and decreased carbohydrate consumption. Children with greater variability in sleep duration and timing had greater energy intake from fat and protein sources.

CONCLUSION

Allowing for the opportunity to educate parents on the importance of maintaining regular, adequate sleep and relationships between sleep and dietary intake may decrease the risk of childhood obesity in this high-risk pediatric population.

Examining the Variability of Sleep Patterns during Treatment for Chronic Insomnia: Application of a Location-Scale Mixed Model

STUDY OBJECTIVES

The purpose of this study was to introduce a novel statistical technique called the location-scale mixed model that can be used to analyze the mean level and intra-individual variability (IIV) using longitudinal sleep data.

METHODS

We applied the location-scale mixed model to examine changes from baseline in sleep efficiency on data collected from 54 participants with chronic insomnia who were randomized to an 8-week Mindfulness-Based Stress Reduction (MBSR; n = 19), an 8-week Mindfulness-Based Therapy for Insomnia (MBTI; n = 19), or an 8-week self-monitoring control (SM; n = 16). Sleep efficiency was derived from daily sleep diaries collected at baseline (days 1-7), early treatment (days 8-21), late treatment (days 22-63), and post week (days 64-70). The behavioral components (sleep restriction, stimulus control) were delivered during late treatment in MBTI.

RESULTS

For MBSR and MBTI, the pre-to-post change in mean levels of sleep efficiency were significantly larger than the change in mean levels for the SM control, but the change in IIV was not significantly different. During early and late treatment, MBSR showed a larger increase in mean levels of sleep efficiency and a larger decrease in IIV relative to the SM control. At late treatment, MBTI had a larger increase in the mean level of sleep efficiency compared to SM, but the IIV was not significantly different.

CONCLUSIONS

The location-scale mixed model provides a two-dimensional analysis on the mean and IIV using longitudinal sleep diary data with the potential to reveal insights into treatment mechanisms and outcomes.

Actigraphy-assessed sleep during school and vacation periods: a naturalistic study of restricted and extended sleep opportunities in adolescents

School-related sleep restriction in adolescents has been identified by studies comparing weekday and weekend sleep. This study compared weekday and vacation sleep to assess restricted and extended sleep opportunities. One-hundred and forty-six adolescents (47.3% male) aged 16.2 ± 1.0 years (M ± SD) from the general community wore an actigraph continuously for 4 weeks: the last week of a school term (Time-E), the following 2-week vacation, and the first week of the next term. Self-reported sleep was assessed for each of the three time intervals, and chronotype was assessed using the Morningness-Eveningness Questionnaire at Time-E. Daily actigraphy bedtime, rise-time, time-in-bed, total sleep time, sleep onset latency, sleep efficiency, and % wake after sleep onset were analysed using latent growth curve modelling. The removal of school-related sleep restriction was associated with an abrupt delay in sleep timing and increase in sleep duration. Subsequently, bedtime and rise-time showed further linear delays throughout the vacation, while changes in time-in-bed were non-significant. Sleep onset latency increased linearly, peaking in the middle of the second vacation week. Across the first vacation week, total sleep time and sleep efficiency linearly decreased, while % wake after sleep onset increased. These changes stabilized during the second vacation week. Older age and eveningness were associated with later bedtime and rise-time, whilst females had longer time-in-bed, total sleep time and sleep onset latency. Compared with school days, sleep during the vacation was characterized by later timing, longer duration, lower quality and greater variability. Recovery from school-related sleep restriction appeared to be completed within the 2 weeks of naturalistic extended sleep.

Sleep variability, health-related practices, and inflammatory markers in a community dwelling sample of older adults

OBJECTIVE

To explore relationships between wake- and sleep-related health behaviors and circulating concentrations of inflammatory markers (interleukin [IL]-6 and tumor necrosis factor [TNF]-α) in a cohort of community dwelling older adults. Low-grade chronic inflammation is an important risk factor for age-related morbidity. Health behaviors, including average aggregate measures of sleep, have been linked to increased inflammation in older adults. Variability in sleep timing may also be associated with increased inflammation.

METHOD

Participants were community dwelling older adults ≥ 60 years (n = 222: 39 bereaved, 55 caregivers, 52 with insomnia, and 76 good sleepers). Mean values and intraindividual variability in sleep, as well as caffeine and alcohol use, exercise, and daytime napping, were assessed by sleep diaries. Blood samples were obtained in the morning.

RESULTS

Several interactions were noted between sleep behaviors, inflammatory markers, and participant group. Greater variability in wake time and time in bed was associated with higher IL-6 among good sleepers relative to caregivers and older adults with insomnia. Good sleepers who consumed moderate amounts of alcohol had the lowest concentrations of IL-6 compared with the other three groups who consumed alcohol. Insomnia subjects, but not good sleepers, showed increased concentrations of IL-6 associated with caffeine use. Caregivers showed increased concentrations of TNF-α with alcohol use relative to good sleepers. Greater variability in bedtime, later wake times, and longer time in bed was associated with higher TNF-α regardless of group.

CONCLUSIONS

Moderation and regularity in the practice of certain health behaviors, including sleep practices, were associated with lower plasma levels of inflammatory markers in older adults. Life circumstances and specific sleep disorders may modify these associations.