Wisconsin Sleep Cohort Study Research Articles

Objectively measured daytime sleepiness predicts weight change among adults: Findings from the Wisconsin Sleep Cohort Study

ObjectiveBody mass index (BMI) trajectories are associated with night-time sleep, but it is not clear how they relate to daytime sleepiness in population data. This study aimed to examine longitudinal associations between levels and changes in daytime sleepiness and BMI trajectories among men and women. MethodsWe estimated growth curve models among 827 participants in the Wisconsin Sleep Cohort Study (mean [sd] age = 55.2 [8.0] years at baseline). The outcome variable was BMI (kg/m2) and the key predictor was daytime sleepiness measured by Multiple Sleep Latency Test (MSLT) scores. Covariates included demographics, health behaviors, retirement status, stimulant use, and depressive symptoms. In sensitivity analyses, we evaluated the potential effects of cardiovascular disease, shift work status, and sleep apnea on the robustness of sleepiness and BMI associations. ResultsAt the between-person level, men who were sleepier had higher BMI levels. At the within-person level, age moderated the positive association between sleepiness and BMI among women. Specifically, young women who became sleepier over time gained more BMI than older women with comparable increases in sleepiness. Furthermore, while BMI tended to increase with age among women, BMI trajectories were steeper among sleepy women than among well-rested women, who experienced less increase in BMI over time. ConclusionThe study suggested that levels and changes in daytime sleepiness as objectively measured by MSLT scores are associated with body mass among adults.

Prevalence and Course of Idiopathic Hypersomnia in the Wisconsin Sleep Cohort Study.

Idiopathic hypersomnia (IH) is a CNS disorder of hypersomnolence of unknown etiology. Due to the requirement for objective sleep testing to diagnose the disorder, there are currently no population-based estimates of the prevalence of IH nor data regarding the longitudinal course of IH in naturalistic settings. Subjective and objective data from the Wisconsin Sleep Cohort study were used to identify cases with probable IH from participants with polysomnography and multiple sleep latency test data. Demographic, polysomnographic, and symptom-level data were compared between those with and without IH. Longitudinal trajectories of daytime sleepiness among those with IH were assessed to evaluate symptom persistence or remission over time. From 792 cohort study participants with available polysomnography and multiple sleep latency test data, 12 cases with probable IH were identified resulting in an estimated prevalence of IH of 1.5% (95% CI 0.7-2.5, p < 0.0001). Consistent with inclusion/exclusion criteria, cases with IH had more severe sleepiness and sleep propensity, despite similar or longer sleep times. Longitudinal data (spanning 12.1 ± 4.3 years) demonstrated a chronic course of sleepiness for most of the cases with IH, though pathologic somnolence remitted in roughly 40% of cases. These results demonstrate IH is more common in the working population than generally assumed with a prevalence on par with other common neurologic and psychiatric conditions. Further efforts to identify and diagnose those impaired by unexplained daytime somnolence may help clarify the causes of IH and the mechanisms underlying symptomatic remission.

Cardiorespiratory Fitness Attenuates the Deleterious Effects of Sleep Apnea on Cerebral Structure and Perfusion in the Wisconsin Sleep Cohort Study.

Emerging evidence suggests that age-related changes in cerebral health may be sensitive to vascular risk modifiers, such as physical activity and sleep. We examine whether cardiorespiratory fitness modifies the association of obstructive sleep apnea (OSA) severity with MRI-assessed measures of cerebral structure and perfusion. Using data from a cross-sectional sample of participants (n = 129, 51% female, age range 49.6-85.3 years) in the Wisconsin Sleep Cohort study, we estimated linear models of MRI-assessed total and regional gray matter (GM) and white matter (WM) volumes, WM hyperintensity (WMH:ICV ratio), total lesion volume, and arterial spin labeling (ASL) cerebral blood flow (CBF), using an estimated measure of cardiorespiratory fitness (CRF) and OSA severity as predictors. Participants' sleep was assessed using overnight in-laboratory polysomnography, and OSA severity was measured using the apnea-hypopnea index (AHI), or the mean number of recorded apnea and hypopnea events per hour of sleep. The mean±SD time difference between PSG data collection and MRI data collection was 1.7±1.5 years (range: [0, 4.9 years]). OSA severity was associated with reduced total GM volume (β=-0.064; SE = 0.023; p = 0.007), greater total WM lesion volume (interaction p = 0.023), and greater WMHs (interaction p = 0.017) in less-fit subjects. Perfusion models revealed significant differences in the association of AHI and regional CBF between fitness groups (interaction ps < 0.05). This work provides new evidence for the protective role of cardiorespiratory fitness against the deleterious effects of OSA on brain aging in late-middle age to older adults.

DAYTIME SLEEPINESS AND WEIGHT CHANGE AMONG ADULTS: FINDINGS FROM THE WISCONSIN SLEEP COHORT STUDY

Abstract BMI trajectories are associated with nighttime sleep, but it is less clear how they relate to daytime sleepiness. We examined the association between levels and changes in daytime sleepiness and BMI among men and women using growth curve models among 1047 participants in the Wisconsin Sleep Cohort Study (mean [sd] age = 51.1 [8.0] years at baseline). The outcome variable was BMI (kg/m2). Key predictors were self-reported sleepiness measured by the Epworth Sleepiness Scale (ESS), and the objective Multiple Sleep Latency Test (MSLT) scores at each data collection wave. Men, but not women, who were sleepier had higher BMI levels. Age moderated the association between changes in ESS and MSLT sleepiness and BMI trajectories. The association was weaker for older men, but stronger for younger men; such effect was the opposite for women. The MSLT models further suggested that women who were sleepier had steeper increases in BMI over time.

Metabolic health disparities driven by financial stress: Behavioural adaptation or modification?

Financial stress has been linked to an increased risk of metabolic syndrome, yet, it remains unclear whether suboptimal sleep duration and physical inactivity are the adaptive responses to financial stress or effect modifiers in the association between financial stress and metabolic syndrome. Hence, this study aims to examine whether physical activity and sleep duration mediate or moderate the bivariate association between financial stress and metabolic syndrome. A prospective secondary analysis was conducted using data from the Wisconsin Sleep Cohort Study (N=445, mean [SD] age=64 [7] years). Baseline moderation effect was examined using subgroup analysis with model constraints; prospective mediation model was examined using bias-corrected bootstrap confidence intervals. Results indicate that participants with higher financial stress were less likely to meet physical activity and sleep recommendations. Baseline moderation analysis indicates that meeting current recommendations of sleep duration and physical activity attenuated the association between financial stress and metabolic syndrome. In the prospective mediation analysis, weekly physical activity levels partially mediated the relationship between financial stress and metabolic syndrome, but sleep duration did not mediate this relationship. In conclusion, the joint effect of optimal sleep duration and physical activity disassociates financial stress from the risk of metabolic syndrome. Future interventions addressing metabolic risk might achieve better outcomes if clinicians and researchers factor in the behavioral adaptation of physical inactivity in financially stressed adults (Clinical Trial Registration: NCT00005557).

Cardiorespiratory fitness attenuates the deleterious effects of sleep apnea on cerebral structure, perfusion, and risk of Alzheimer’s disease in the Wisconsin Sleep Cohort study

AbstractBackgroundEmerging evidence suggests that age‐related changes in cerebral structure and perfusion—hallmark features of preclinical Alzheimer’s disease (AD)—may be sensitive to vascular risk modifiers such as physical exercise and sleep quality. Here, we examine whether cardiorespiratory fitness modifies the effects of obstructive sleep apnea (OSA) on cerebral structure, perfusion, and AD risk.MethodUsing data from a sample of participants (n=134 for analyses of imaging outcomes and n=1,182 for analyses examining AD outcomes) in the Wisconsin Sleep Cohort (WSC) study, we examined cross‐sectional associations between OSA severity, estimated cardiorespiratory fitness (eCRF), and their interaction with MRI‐assessed total and regional gray (GM) and white matter (WM) volumes, WM hyperintensities (WMHs), total lesion volume, and arterial spin labeling cerebral blood flow (CBF), using multiple linear regression models adjusted for age, sex, BMI, hypertension, and education level. We further assessed whether eCRF modifies the associations between OSA and risk of AD using Cox proportional hazard models.ResultOSA severity was associated with greater total lesion volume, reduced total GM volume, and greater WMHs among less‐fit, but not among more‐fit, subjects. Perfusion models likewise revealed significant regional differences in CBF between fitness groups. OSA severity was likewise associated with greater risk of AD among less‐fit individuals, but there was no significant association among the more‐fit.ConclusionThis work provides new evidence for the protective role of cardiorespiratory fitness against the deleterious effects of OSA on brain aging and AD.

Association between stressful life events and non-optimal lipid levels among women with hyperlipidaemia.

Psychological stress has been linked to lipid dysregulation with noticeable gender differences, but it remains unclear whether women are more susceptible to non-optimal lipid levels than men, when experiencing stressful life events. This study aims to examine the association between stressful life events and non-optimal lipid levels among persons with hyperlipidaemia and whether the association differs between men and women. A nested case-control study was performed using data from the Wisconsin Sleep Cohort (WSC) Study from 2011 to 2015, including 224 participants with hyperlipidaemia and without a history of myocardial infarction or heart failure. Among them, 63 participants with non-optimal LDL cholesterol or triglyceride levels were identified as cases, and 161 participants with optimal LDL cholesterol and triglyceride levels were identified as controls. Cases and controls were traced back to their self-reported life events collected through the Retirement and Sleep Trajectories study during 2010-11. The association between stressful life events and non-optimal lipid levels was examined using multivariable logistic regression; confounding effects were addressed using propensity score weighting and Mahalanobis distance matching; gender differences were examined using subgroup analysis. Results showed that a higher number of stressful life events during 2010-11 was associated with greater odds of non-optimal lipid levels during 2011-15 (odds ratio = 1.45, P = 0.03) among women with hyperlipidaemia, whereas the association was not significant among men with hyperlipidaemia (P = 0.910). Future studies are needed to examine the underlying mechanisms that explain gender differences in the association between stressful life events and non-optimal lipid levels. ClinicalTrials.gov NCT00005557.

The genetic etiology of periodic limb movement in sleep.

Periodic limb movement in sleep is a common sleep phenotype characterized by repetitive leg movements that occur during or before sleep. We conducted a genome-wide association study (GWAS) of periodic limb movements in sleep (PLMS) using a joint analysis (i.e., discovery, replication, and joint meta-analysis) of four cohorts (MrOS, the Wisconsin Sleep Cohort Study, HypnoLaus, and MESA), comprised of 6843 total subjects. The MrOS study and Wisconsin Sleep Cohort Study (N = 1745 cases) were used for discovery. Replication in the HypnoLaus and MESA cohorts (1002 cases) preceded joint meta-analysis. We also performed LD score regression, estimated heritability, and computed genetic correlations between potentially associated traits such as restless leg syndrome (RLS) and insomnia. The causality and direction of the relationships between PLMS and RLS was evaluated using Mendelian randomization. We found 2 independent loci were significantly associated with PLMS: rs113851554 (p = 3.51 × 10-12, β = 0.486), an SNP located in a putative regulatory element of intron eight of MEIS1 (2p14); and rs9369062 (p = 3.06 × 10-22, β = 0.2093), a SNP located in the intron region of BTBD9 (6p12); both of which were also lead signals in RLS GWAS. PLMS is genetically correlated with insomnia, risk of stroke, and RLS, but not with iron deficiency. Pleiotropy adjusted Mendelian randomization analysis identified a causal effect of RLS on PLMS. Because PLMS is more common than RLS, PLMS may have multiple causes and additional studies are needed to further validate these findings.

0115 Discrepancies Between Actual and Ideal Bedtime are Associated with Cognitive Performance

Abstract Introduction Experimental studies have shown that acute sleep-circadian misalignment can lead to cognitive deficits. Additionally, chronic jetlag among pilots and long-term exposure to shiftwork are associated with worse cognitive performance. This study investigated whether small daily discrepancies in actual versus perceived ideal bedtime are associated with cognitive performance. Methods A subset of Wisconsin Sleep Cohort study participants (N=750; 58% male; mean[range] age 59 [38-78] years) participated in a neurocognitive test battery, provided a 6-night sleep diary, and completed questionnaires at the same study visit. The neurocognitive assessment included the Controlled Oral Word Association Test, Trails Making Test Part B, Grooved Pegboard Test, Auditory Verbal Learning Test, Digit Cancellation, and Symbol Digit Modalities Test. Weekday bedtimes from the sleep diary were averaged to represent “actual” bedtime. “Ideal” bedtime was represented by the answer to the question from the Horne-Ostberg Morningness-Eveningness Questionnaire: If you were free of any schedule and could go to bed at any time you wanted, what time would that be? Bedtime mismatch was represented as (ideal bedtime – actual bedtime). Cognitive performance was regressed on bedtime mismatch (separate models for each cognitive test) in linear regression models, adjusting for age, sex, BMI, sedative and stimulant use, average total sleep time, actual bedtime, smoking, caffeine consumption, and education level. Results There was a significant association between bedtime mismatch and performance on both the Grooved Pegboard (p=0.02) and Symbol Digit Modalities (p=0.02) tests, and a borderline significant association (p=0.09) with performance on the Oral Word test. On average, participants that had actual bedtimes that were later than ideal bedtimes demonstrated worse cognitive performance, while actual bedtimes that were earlier than ideal bedtimes were associated with better performance. No associations were found for the other 3 cognitive tests. Conclusion Going to bed at a time that is later than perceived ideal bedtime may be associated with cognitive deficits, even after accounting for actual bedtime and total sleep time. Support (If Any) This work was supported by the National Heart, Lung, and Blood Institute (R01HL62252), National Institute on Aging (R01AG058680) and the National Center for Research Resources (1UL1RR025011) at the US National Institutes of Health.

Cardiorespiratory Fitness Attenuates the Deleterious Effects of Sleep Apnea on Cerebral Structure and Perfusion in the Wisconsin Sleep Cohort Study

Cardiorespiratory Fitness Attenuates the Deleterious Effects of Sleep Apnea on Cerebral Structure and Perfusion in the Wisconsin Sleep Cohort Study

Habitual Sleep, Sleep Duration Differential, and Weight Change Among Adults

We assessed longitudinal associations between diary-measured sleep duration and clinically assessed body mass index (BMI) among 784 men and women enrolled in the Wisconsin Sleep Cohort Study (mean [SD] age = 51.1 [8.0] years at baseline). The outcome was BMI (kg/m2). Key predictors were habitual sleep duration (defined as average weekday nighttime sleep duration) and sleep duration differential (defined as the difference between average weekday and average weekend nighttime sleep duration) at each data collection wave. Men with shorter habitual sleep duration on weekdays had higher BMI than men with longer habitual sleep duration on weekdays. Participants with larger differentials between weekday and weekend sleep duration experienced more rapid BMI gain over time for both men and women. Inadequate sleep, characterized as shorter habitual sleep during weekdays and larger weekday-weekend sleep differential, is positively associated with BMI levels and trajectories among men and women in mid-to-late life.

Napping characteristics and cognitive function in older adults

AbstractBackgroundBrief naps are considered beneficial for cognition in younger adults, whereas emerging evidence suggests excessive napping may be associated with dementia in older adults. The effects of napping parameters on different cognitive domains remain controversial, and the role of reasons for napping is poorly understood.MethodWe used cross‐sectional data from the Wisconsin Sleep Cohort Study. Participants reported on naps that lasted more than 5 minutes over the past month, nap frequency and length, and reasons for napping. Participants reported nighttime sleep duration and quality, and completed overnight polysomnography to assess sleep apnea. Six neurocognitive tests measured attention, memory, learning and executive function.ResultOf the 686 participants (mean (SD), [range] age 65.0 (7.1), [50‐85] years; 44% women), 500 (73%) reported a nap &gt;5 minutes during the past month and 184 (27%) napped at least four times per week. The average nap length was 41.4 minutes. 187 (27%) napped due to not getting enough sleep at night, 52 (7.6%) napped due to illness or medical reasons, 256 (37%) napped to feel refreshed, 27 (3.9%) napped because they felt unhappy or unwell, and 139 (20%) napped for other reasons. After adjustment for age, sex, body mass index, alcohol intake, smoking, depression, and history of diabetes and cardiovascular diseases, those with more frequent naps performed worse on three neurocognitive tests (P&lt;0.02): Symbol‐Digit Modalities (SDMT) (b=‐1.9, standard error (SE)=0.7), Oral Word Fluency (b=‐2.3, SE=0.9) and Auditory Verbal Learning Test (b=‐1.9, SE=0.8). Those with longer naps performed worse on Grooved Pegboard (b=11.0, SE=2.8), Trails B (b=8.1, SE=2.3), SDMT (b=‐1.9, SE=0.4) and Digit Cancellation (b=14.4, SE=5.6). Further adjustment for sleep duration, quality and sleep apnea did not appreciably alter results. There were no associations between specific reasons for napping and cognition.ConclusionAmong middle‐ to older‐aged adults, more frequent naps were associated with worse attention and memory and learning; longer naps were associated with worse attention and executive function. Longitudinal studies are needed to examine how napping characteristics predict cognition as individuals age and to further explore reasons for napping during this transition.

Habitual sleep, sleep duration differential, and weight change among adults: Findings from the Wisconsin Sleep Cohort Study

ObjectivesAssess longitudinal associations between diary-measured sleep duration and clinically assessed body mass index (BMI). DesignMultilevel growth curve analyses examined how within-person changes and between-person differences in habitual sleep duration were associated with BMI trajectories. SettingSleep diaries across 2-6 consecutive weekday and weekend nights at each data collection point, repeatedly collected at approximate 4-year intervals, for an average of 9.2 (standard deviation [SD] = 3.6) years between 1989 and 2011. ParticipantsAbout 784 participants (47% women) enrolled in the Wisconsin Sleep Cohort Study (mean [SD] age = 51.1 [8.0] years at baseline). MeasurementsThe outcome variable was BMI (kg/m2). Key predictors were habitual sleep duration (defined as average weekday nighttime sleep duration) and sleep duration differential (defined as the difference between average weekday and average weekend nighttime sleep duration) at each data collection wave. ResultsMen with shorter habitual sleep duration on weekdays had higher BMI than men with longer habitual sleep duration on weekdays (β = −0.90 kg/m2/hour, se = 0.34, p = .008). Participants with larger differentials between weekday and weekend sleep duration experienced more rapid BMI gain over time for both men (β = 0.033 kg/m2/year per hour differential, se = 0.017, p = .044) and women (β = 0.057 kg/m2/year per hour differential, se = 0.027, p = .036). ConclusionThis study suggests that habitual short sleep is associated with higher BMI levels in men and that a larger weekday-weekend sleep differential is associated with increasing BMI trajectories among both men and women in mid-to-late life.

Physiological sleep measures predict time to 15-year mortality in community adults: Application of a novel machine learning framework.

Clarifying whether physiological sleep measures predict mortality could inform risk screening; however, such investigations should account for complex and potentially non-linear relationships among health risk factors. We aimed to establish the predictive utility of polysomnography (PSG)-assessed sleep measures for mortality using a novel permutation random forest (PRF) machine learning framework. Data collected from the years 1995 to present are from the Sleep Heart Health Study (SHHS; n=5,734) and the Wisconsin Sleep Cohort Study (WSCS; n=1,015), and include initial assessments of sleep and health, and up to 15years of follow-up for all-cause mortality. We applied PRF models to quantify the predictive abilities of 24 measures grouped into five domains: PSG-assessed sleep (four measures), self-reported sleep (three), health (eight), health behaviours (four), and sociodemographic factors (five). A 10-fold repeated internal validation (WSCS and SHHS combined) and external validation (training in SHHS; testing in WSCS) were used to compute unbiased variable importance metrics and associated p values. We observed that health, sociodemographic factors, and PSG-assessed sleep domains predicted mortality using both external validation and repeated internal validation. The PSG-assessed sleep efficiency and the percentage of sleep time with oxygen saturation <90% were among the most predictive individual measures. Multivariable Cox regression also revealed the PSG-assessed sleep domain to be predictive, with very low sleep efficiency and high hypoxaemia conferring the highest risk. These findings, coupled with the emergence of new low-burden technologies for objectively assessing sleep and overnight oxygen saturation, suggest that consideration of physiological sleep measures may improve risk screening.

244 Physical fitness attenuates the deleterious association of sleep apnea with gray matter volume in the Wisconsin Sleep Cohort Study

Abstract Introduction Recent evidence has illustrated that gray matter (GM) atrophy, a diagnostic hallmark of Alzheimer’s disease (AD), may be influenced by psychosocial risk modifiers such as physical exercise and sleep. Cardiorespiratory fitness, a measure of oxygen delivery and utilization during exercise, is positively associated with both sleep quality and gray matter volume in brain areas associated with age-related cognitive decline, such as the hippocampus. In contrast, sleep apnea has been linked to global and regional gray matter atrophy, which is thought to be driven in-part by the incomplete modulation of cardiovascular and respiratory control during sleep. This study examines whether cardiorespiratory fitness modifies the deleterious relationship between sleep apnea and GM volume in a sample of non-demented older participants from the Wisconsin Sleep Cohort (WSC). Methods Using data from a subset of WSC participants (n=129, 51% female, mean [range] age at baseline=68 [49-85] years), cardiorespiratory fitness was estimated using a Non-Exercise CardioRespiratory Fitness Measure (NECRFM; based on age, sex, BMI, self-reported physical activity, and resting heart rate). Sleep apnea severity was measured by overnight polysomnography and characterized by the base 10 logarithm of the apnea-hypopnea index, log10(AHI+1). We assembled cross-sectional linear models of MRI-measured total GM volume using NECRFM and log10(AHI+1) as predictors while controlling for age, sex, BMI, education, and hypertension. Regional volumetric changes in the hippocampus and amygdala were assessed using analogous linear models, adjusting both outcome volumetrics for total intracranial volume. Results While the interaction between fitness and apnea severity was not significant (p=0.50), results stratified at the median NECRFM illustrated that among the less fit individuals, higher log10(AHI+1) was associated with a significant reduction in total GM volume (B(SE)=-0.06 (0.02); p=0.007); this relationship was not significant among those who were more fit (B(SE)=-0.03 (0.02); p=0.11). There were no significant effects in the hippocampus or amygdala. Conclusion These results indicate that cardiovascular fitness may attenuate the effect of severe sleep apnea on GM volume in older adults, supporting the protective role of cardiovascular fitness in aging brain health. Support (if any) This work was supported by United States National Institutes of Health grants R01AG058680, R01HL62252, 1R01AG036838, 1UL1RR025011, and R01AG062167.

539 Interactions Between Cardiorespiratory Fitness and Sleep Apnea in Predicting Risk of Alzheimer’s Disease

Abstract Introduction Several studies suggest a link between obstructive sleep apnea (OSA) and Alzheimer’s disease (AD). Additionally, frequent exercise is associated with more favorable AD biomarker profiles, and emerging evidence suggests greater cardiorespiratory fitness levels may be associated with lower risk of cognitive decline. We investigated whether cardiorespiratory fitness modifies the association of OSA and risk of AD. Methods A subset of the Wisconsin Sleep Cohort study participants with study visits starting in 2000 (n=1182, 46% female, mean [range] age at baseline=57 [37–82] years) completed multiple [range, 1–5] in-laboratory protocols that included overnight polysomnography, anthropometric measurements, and questionnaires. Additionally, the National Death Index was searched to determine cause of death among decedents. Cox proportional hazards models estimated relative hazards of AD (self-reported physician diagnosis or indication of AD on the death certificate) associated with the joint effects and the interaction of OSA – characterized by the base 10 logarithm of the apnea-hypopnea index (log10(AHI+1)) – and cardiorespiratory fitness (an index based on age, sex, BMI, self-reported physical activity, and resting heart rate). Additionally, the sample was stratified by fitness level at the 3rd quartile (&amp;gt;75th percentile compared to &amp;lt;75th percentile) and the hazard ratio for log10(AHI+1) was estimated for the lower and higher fitness-level groups. Results were adjusted for age, sex, BMI, and education. Results There were 10 incident cases of AD. The mean [range] fitness level was 7.1 [0–12.3]. 28% of the sample had moderate OSA (AHI 5–15); and 26% had severe OSA (AHI&amp;gt;15). Higher log10(AHI+1) was associated with greater hazards (p=0.03) of AD and there was a significant interaction between log10(AHI) and fitness (p=0.04), such that at greater fitness levels, the effect of log10(AHI) on AD was mitigated. In stratified analysis, among the less fit, the hazard ratio for an increment of 1 in log10(AHI) was 12.8 (95% CI, 1.1–153.8, p=0.04); among those who were more fit, the hazard ratio was not significant. Conclusion More severe OSA is associated with higher risk of AD, and this risk is greater among those with lower levels of cardiorespiratory fitness. Support (if any) This work was supported by US NIH grants R01AG058680, R01AG062167, R01HL62252, 1R01AG036838 and 1UL1RR025011.

Polysomnographic indicators of restorative sleep and body mass trajectories in the Wisconsin Sleep Cohort Study.

Previous research suggests that reductions in restorative, slow-wave (N3), and rapid eye movement (REM) sleep are associated with weight gain and obesity in mid-to-late life. We extend prior work by examining how within-person (WP) changes and between-person (BP) differences in restorative sleep over several years are associated with body mass trajectories among participants in the Wisconsin Sleep Cohort Study (WSCS). We used data from 4,862 polysomnographic (PSG) sleep studies and physical exams collected from 1,187 WSCS participants over an average duration of 14.9 years. Primary measures of interest included body mass index (BMI = kg/m2) and the percentages of time spent in N3 and REM sleep. We estimated a series of linear mixed regression models to examine how WP changes and BP differences in N3 and REM sleep affected BMI trajectories, controlling for other sleep measures, demographic characteristics, and health behaviors as potential confounders. Women in the WSCS experienced more rapid BMI gain than men. With some variation by sex, we found that (1) below-average N3 and REM sleep is associated with above-average BMI, and (2) within-person decreases in N3 and REM sleep over time are associated with gains in BMI. These findings persisted after adjustment for sleep duration and other potential confounders. Our findings highlight the importance of PSG indices of restorative sleep in mid-to-late life, suggesting that future clinical treatments and public health policies will benefit from heightened attention to sleep quality.

Polysomnographic Indicators of Restorative Sleep and Body Mass Trajectories in the Wisconsin Sleep Cohort Study

Previous research suggests that reductions in restorative sleep—i.e., slow-wave (N3) and rapid-eye movement (REM) sleep—are associated with weight gain and obesity in mid-to-late life. This study extends prior work by examining how within-person changes and between-person differences in restorative sleep are associated with body mass trajectories among participants in the Wisconsin Sleep Cohort Study (WSCS). We used data from 4,862 polysomnographic sleep studies and physical exams collected from 1,187 WSCS participants over an average follow-up duration of 15 years. For both men and women, we found that (1) below-average N3 and REM sleep is associated with above-average BMI, and (2) within-person loss of N3 and REM sleep is associated with larger gains in BMI, particularly between ages 30-50. Our findings highlight the importance of restorative sleep in mid-to-late life, suggesting that future clinical treatments and public health policies will benefit from heightened attention to sleep quality.

Gender Differences in the Relationship Between Financial Stress and Metabolic Abnormalities.

Financial stress is associated with higher prevalence of metabolic abnormalities and cardiovascular disease, but the extent to which this association differs by type of metabolic abnormalities or gender is unclear. The study aims were (a) to examine the association between financial stress and the prevalence of common metabolic abnormalities and (b) to test the association for gender differences. A cross-sectional secondary analysis was conducted using data from the Retirement and Sleep Trajectories study, an ancillary study of the Wisconsin Sleep Cohort study. Composite indicator structural equation alpha modeling with a stacking approach was applied in the data analysis. After controlling for covariates, financial stress was positively associated with the prevalence of abdominal obesity, metabolic syndrome, and dyslipidemia, with significant gender differences. Among men, financial stress was positively associated with the prevalence of hypertriglyceridemia. Among women, financial stress was positively associated with the prevalence of prediabetes, abdominal obesity, metabolic syndrome, and dyslipidemia. Men living with financial stress are more likely to have hypertriglyceridemia, a specific metabolic abnormality and risk factor for acute cardiovascular events. However, financial stress in women is associated with a broader array of metabolic abnormalities (e.g., dyslipidemia, prediabetes, abdominal obesity, metabolic syndrome), highlighting a potential risk of multiple chronic conditions later in life.

Longitudinal sleep characteristics and hypertension status: results from the Wisconsin Sleep Cohort Study.

Sleep characteristics such as short sleep duration or sleep-disordered breathing are established predictors of hypertension. However, few studies have used in-lab polysomnography with a longitudinal design to measure how hypertension is associated with different sleep stages over time. The purpose of this study is to examine whether hypertension is associated with the longitudinal course of sleep quality over time. The current study evaluated data from the Wisconsin Sleep Cohort Study, which consists of 1525 adults in a community-based population of middle-aged to older adults followed for approximately 12-25 years. Sleep characteristics were objectively measured using polysomnography and subjectively assessed using a self-report questionnaire on insomnia complaints. We used linear mixed-effects regression models and cumulative logit models to assess whether the interaction of hypertension and time is associated with objective and subjective sleep. We found people with hypertension exhibited a greater decline in total sleep time in rapid eye movement sleep (%) over time than those without hypertension (P < 0.05). Individuals with hypertension had less decline in % N3 sleep over time than those without hypertension (P < 0.05). Among the subjective insomnia complaints, our findings indicate hypertensive individuals have a higher probability of having higher levels of 'difficulties in falling asleep' compared with people without hypertension. These findings suggest that hypertension is associated with modified longitudinal changes of objective and subjective sleep characteristics.