Search tips
Search criteria

Results 1-23 (23)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
1.  Obstructive Sleep Apnea is Associated with Future Subclinical Carotid Artery Disease: Thirteen-Year Follow-up from the Wisconsin Sleep Cohort 
To determine the longitudinal associations between obstructive sleep apnea (OSA), carotid artery intima-media thickness (IMT), and plaque.
Approach and Results
This is a population-based, prospective cohort study conducted from July, 1989 to November, 2012 on 790 randomly selected employed Wisconsin residents who completed a mean of 3.5 (range 1–6) polysomnograms during the study period. OSA was characterized by the apnea-hypopnea index (AHI, events/hour). Common carotid artery IMT and plaque were assessed by B-mode ultrasound. The mean (SD) time from the first polysomnograms to carotid ultrasound was 13.5 (3.6) years. Multivariable regression models were created to estimate the independent associations of baseline and cumulative OSA exposure with subsequent carotid IMT and plaque. At baseline, participants were mean 47.6 (7.7) years old (55% male, 97% white). AHI was 4.4 (9.0) events/hour (range, 0–97); 7% had AHI>15 events/hour. Carotid IMT was 0.755 (0.161) mm; 63% had plaque. Adjusting for age, sex, body-mass index, systolic blood pressure, smoking, and use of lipid-lowering, antihypertensive, and diabetes medications, baseline AHI independently predicted future carotid IMT (β=0.027 mm/unit log10[AHI+1], p=0.049), plaque presence (odds ratio 1.55 [95% confidence intervals 1.02–2.35], p=0.041) and plaque score (odds ratio 1.30 [1.05–1.61], p=0.018). In cumulative risk factor-adjusted models, AHI independently predicted future carotid plaque presence (p=0.012) and score (p=0.039), but not IMT (p=0.608).
Prevalent OSA is independently associated with increased carotid IMT and plaque over a decade later, indicating increased future cardiovascular disease risk.
PMCID: PMC4259877  PMID: 25189572
Atherosclerosis; Carotid arteries; Epidemiology; Sleep apnea; Ultrasound; Sleep disorders
2.  Increased Prevalence of Sleep-Disordered Breathing in Adults 
American Journal of Epidemiology  2013;177(9):1006-1014.
Sleep-disordered breathing is a common disorder with a range of harmful sequelae. Obesity is a strong causal factor for sleep-disordered breathing, and because of the ongoing obesity epidemic, previous estimates of sleep-disordered breathing prevalence require updating. We estimated the prevalence of sleep-disordered breathing in the United States for the periods of 1988–1994 and 2007–2010 using data from the Wisconsin Sleep Cohort Study, an ongoing community-based study that was established in 1988 with participants randomly selected from an employed population of Wisconsin adults. A total of 1,520 participants who were 30–70 years of age had baseline polysomnography studies to assess the presence of sleep-disordered breathing. Participants were invited for repeat studies at 4-year intervals. The prevalence of sleep-disordered breathing was modeled as a function of age, sex, and body mass index, and estimates were extrapolated to US body mass index distributions estimated using data from the National Health and Nutrition Examination Survey. The current prevalence estimates of moderate to severe sleep-disordered breathing (apnea-hypopnea index, measured as events/hour, ≥15) are 10% (95% confidence interval (CI): 7, 12) among 30–49-year-old men; 17% (95% CI: 15, 21) among 50–70-year-old men; 3% (95% CI: 2, 4) among 30–49-year-old women; and 9% (95% CI: 7, 11) among 50–70 year-old women. These estimated prevalence rates represent substantial increases over the last 2 decades (relative increases of between 14% and 55% depending on the subgroup).
PMCID: PMC3639722  PMID: 23589584
adult; middle age; obesity; sleep
3.  Do sleep-deprived adolescents make less-healthy food choices? 
The British journal of nutrition  2014;111(10):1898-1904.
Short sleep duration among children and adolescents has been reported to be associated with elevated BMI and other adverse health outcomes. Food choices are one proposed mechanism through which this association may occur. In the present study, we examined whether self-reported habitual sleep duration is associated with vegetable and fruit consumption and fast food consumption. Using cross-sectional data from the National Longitudinal Study of Adolescent Health (n 13 284), we estimated three nested logistic regression models for two outcome variables: daily vegetable and fruit consumption and previous week’s fast food consumption. The adjusted models included demographic and social/behavioural covariates. Self-reported habitual short sleep duration (<7 h/night) was associated with reduced odds of vegetable and fruit consumption compared with the recommended sleep duration (>8 h/night) (OR 0·66, P < 0·001), even after adjusting for demographic and social/behavioural factors (OR 0·75, P < 0·001). Short sleep duration was also associated with increased odds of fast food consumption (OR 1·40, P < 0·001) even after adjustment (OR 1·20, P < 0·05). Food choices are significantly associated with sleep duration and may play an important role in the mediation of the association between sleep and health among adolescents.
PMCID: PMC4454607  PMID: 24524288
Sleep; Sleep duration; Diet; Adolescents; Food choices
4.  The Sleep-Time Cost of Parenting: Sleep Duration and Sleepiness Among Employed Parents in the Wisconsin Sleep Cohort Study 
American Journal of Epidemiology  2013;177(5):394-401.
Insufficient sleep is associated with poor health and increased mortality. Studies on whether parenthood (including consideration of number and ages of children) is associated with sleep duration or sleep problems are scant and inconclusive. Using data collected in the Wisconsin Sleep Cohort Study (n = 4,809) between 1989 and 2008, we examined cross-sectional associations of number and ages of children with self-reported parental sleep duration, daytime sleepiness, and dozing among employed adults. Longitudinal change in sleep duration over 19 years was examined to evaluate changes in parental sleep associated with children transitioning into adulthood (n = 833). Each child under age 2 years was associated with 13 fewer minutes of parental sleep per day (95% confidence interval (CI): 5, 21); each child aged 2–5 years was associated with 9 fewer minutes of sleep (95% CI: 5, 13); and each child aged 6–18 years was associated with 4 fewer minutes (95% CI: 2, 6). Adult children were not associated with shorter parental sleep duration. Parents of children over age 2 years were significantly more likely to experience daytime sleepiness and dozing during daytime activities. Parents of minor children at baseline had significantly greater increases in sleep duration over 19 years of follow-up. Parenting minor children is associated with shorter sleep duration. As children age into adulthood, the sleep duration of parents with more children approaches that of parents with fewer children.
PMCID: PMC3626047  PMID: 23378502
adult; cohort studies; humans, middle aged; parents; sleep; sleep duration
Annals of epidemiology  2013;24(3):214-221.
Pathways by which the social and built environments affect health can be influenced by differences between perception and reality. This discordance is an important for understanding health impacts of the built environment. This study examines associations between perceived and objective measures of 12 non-residential destinations, as well as previously unexplored sociodemographic, lifestyle, neighborhood and urbanicity predictors of discordance.
Perceived neighborhood data were collected from participants of the Survey of the Health of Wisconsin (SHOW), using a self-administered questionnaire. Objective data were collected using the Wisconsin Assessment of the Social and Built Environment, an audit-based instrument assessing built environment features around each participant’s residence.
Overall, there was relatively high agreement, ranging from 50% for proximity to parks to >90% for golf courses. Education, positive neighborhood perceptions, and rurality were negatively associated with discordance. Associations between discordance and depression, disease status, and lifestyle factors appeared to be modified by urbanicity level.
These data show perceived and objective neighborhood environment data are not interchangeable and the level of discordance is associated with or modified by individual and neighborhood factors, including level of urbanicity. These results suggest that consideration should be given to including both types of measures in future studies.
PMCID: PMC3947547  PMID: 24467991
Epidemiological methods; Environment Design; Obesity; Perception; Validity (Epidemiology); Rural Population; Urban Population
6.  Ethnic Variation in the Association between Sleep and Body Mass among U.S. Adolescents 
We investigate whether differences in sleep duration help explain ethnic disparities in body mass index (BMI) among U.S. adolescents. We also evaluate the functional form of the association between sleep duration and BMI, and investigate whether this association varies by sex and ethnicity.
Participants and Methods
We analyzed restricted-use data from the first 2 waves of the National Longitudinal Study of Adolescent Health (n=30 133) to evaluate linear and quadratic associations between sleep duration and BMI. Through a series of models that incorporated interaction terms between sex, ethnicity and sleep duration, we also assessed whether (1) sleep duration mediates associations between ethnicity and BMI, and (2) associations between sleep duration and BMI differ for girls and boys from different ethnic groups.
A linear association between sleep duration and BMI best fits the data in this large sample of U.S. adolescents. We find no evidence that sleep duration contributes substantially to ethnic disparities in BMI. However, we detect significant differences in the association between sleep duration and BMI by sex and ethnicity. Sleep duration is negatively associated with BMI among white, Hispanic and Asian boys, positively associated with BMI among black girls, and not related to BMI among black boys or girls from white, Hispanic or Asian ethnic groups.
Despite significant associations between sleep duration and BMI for certain groups of adolescents, we find no evidence that ethnic differences in sleep duration exacerbate ethnic disparities in BMI. Future research should explore mechanisms that underlie ethnic differences in the association between sleep and BMI.
PMCID: PMC4090255  PMID: 24480862
Adolescent Health; Body Mass Index-BMI; Ethnicity; Health Disparities; Sleep
7.  Dissociation of Obstructive Sleep Apnea from Hypersomnolence and Obesity in Patients with Stroke 
Background and Purpose
Obstructive sleep apnea (OSA) is seldom considered in the diagnostic investigation in the post-stroke period even though it is a stroke risk factor and has adverse prognostic implications following stroke. One reason might be that widely used clinical criteria for detection of OSA in the general community are not applicable in stroke patients. We hypothesized that stroke patients report less sleepiness and are less obese than subjects from a community sample with the same severity of OSA.
We performed polysomnography in 96 consecutive stroke patients admitted to a stroke rehabilitation unit and in a community sample of 1,093 subjects without a history of stroke. We compared the degrees of subjective sleepiness assessed by the Epworth Sleepiness Scale (ESS) and body-mass index between the two samples according OSA-categories assessed by the frequency of apneas and hypopneas per hour of sleep (<5, no OSA; 5 to <15 mild OSA; and ≥15, moderate-severe OSA).
Compared to the community sample, stroke patients with OSA had significantly lower ESS scores and BMI for mild OSA (ESS 9.3±0.3 versus 5.6±0.5, p<0.001, and BMI 33.1±0.5 versus 28.5±1.1, p<0.048), and for moderate-severe OSA (ESS 9.7±0.4 versus 7.1±0.9, p=0.043, and BMI 36.4±0.8 versus 27.2±0.8 kg/m2, p<0.025).
For a given severity of OSA, stroke patients had less daytime sleepiness and lower BMI than subjects without stroke. These factors may make the diagnosis OSA elusive in the post-stroke period, and preclude many such patients from the potential benefits of OSA therapy.
PMCID: PMC4230450  PMID: 20075361
sleep disorders; apnea; rehabilitation; obesity
8.  The Wisconsin Assessment of the Social and Built Environment (WASABE): a multi-dimensional objective audit instrument for examining neighborhood effects on health 
BMC Public Health  2014;14:1165.
Growing evidence suggests that mixed methods approaches to measuring neighborhood effects on health are needed. The Wisconsin Assessment of the Social and Built Environment (WASABE) is an objective audit tool designed as an addition to a statewide household-based health examination survey, the Survey of the Health of Wisconsin (SHOW), to objectively measure participant’s neighborhoods.
This paper describes the development and implementation of the WASABE and examines the instrument’s ability to capture a range of social and built environment features in urban and rural communities. A systematic literature review and formative research were used to create the tool. Inter-rater reliability parameters across items were calculated. Prevalence and density of features were estimated for strata formed according to several sociodemographic and urbanicity factors.
The tool is highly reliable with over 81% of 115 derived items having percent agreement above 95%. It captured variance in neighborhood features in for a diverse sample of SHOW participants. Sidewalk density in neighborhoods surrounding households of participants living at less than 100% of the poverty level was 67% (95% confidence interval, 55-80%) compared to 34% (25-44%) for those living at greater than 400% of the poverty level. Walking and biking trails were present in 29% (19-39%) of participant buffer in urban areas compared to only 7% (2-12%) in rural communities. Significant environmental differences were also observed for white versus non-white, high versus low income, and college graduates versus individuals with lower level of education.
The WASABE has strong inter-rater reliability and validity properties. It builds on previous work to provide a rigorous and standardized method for systematically gathering objective built and social environmental data in a number of geographic settings. Findings illustrate the complex milieu of built environment features found in participants neighborhoods and have relevance for future research, policy, and community engagement purposes.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2458-14-1165) contains supplementary material, which is available to authorized users.
PMCID: PMC4289353  PMID: 25391283
Neighborhoods; Built environment; Social environment; Population health; Measurement; Urban; Rural; Chronic disease; Prevention; Physical activity; Methods; Audit tool
9.  Sleep spindle detection: crowdsourcing and evaluating performance of experts, non-experts, and automated methods 
Nature methods  2014;11(4):385-392.
Sleep spindles are discrete, intermittent patterns of brain activity that arise as a result of interactions of several circuits in the brain. Increasingly, these oscillations are of biological and clinical interest because of their role in development, learning, and neurological disorders. We used an internet interface to ‘crowdsource’ spindle identification from human experts and non-experts, and compared performance with 6 automated detection algorithms in middle-to-older aged subjects from the general population. We also developed a method for forming group consensus, and refined methods of evaluating the performance of event detectors in physiological data such as polysomnography. Compared to the gold standard, the highest performance was by individual experts and the non-expert group consensus, followed by automated spindle detectors. Crowdsourcing the scoring of sleep data is an efficient method to collect large datasets, even for difficult tasks such as spindle identification. Further refinements to automated sleep spindle algorithms are needed for middle-to-older aged subjects.
PMCID: PMC3972193  PMID: 24562424 CAMSID: cams3998
Sleep EEG; electroencephalography; PSG; polysomnography; Performance evaluation; Benchmarking; Reliability; Validity; Agreement; Sensitivity; Specificity; Precision; Recall; Signal analysis; Pattern recognition; Event detection; EEG microarchitecture; EEG features; Sleep Spindles
10.  Sleep spindle detection: crowdsourcing and evaluating performance of experts, non-experts, and automated methods 
Nature methods  2014;11(4):385-392.
Sleep spindles are discrete, intermittent patterns of brain activity that arise as a result of interactions of several circuits in the brain. Increasingly, these oscillations are of biological and clinical interest because of their role in development, learning, and neurological disorders. We used an internet interface to ‘crowdsource’ spindle identification from human experts and non-experts, and compared performance with 6 automated detection algorithms in middle-to-older aged subjects from the general population. We also developed a method for forming group consensus, and refined methods of evaluating the performance of event detectors in physiological data such as polysomnography. Compared to the gold standard, the highest performance was by individual experts and the non-expert group consensus, followed by automated spindle detectors. Crowdsourcing the scoring of sleep data is an efficient method to collect large datasets, even for difficult tasks such as spindle identification. Further refinements to automated sleep spindle algorithms are needed for middle-to-older aged subjects.
PMCID: PMC3972193  PMID: 24562424
Sleep EEG; electroencephalography; PSG; polysomnography; Performance evaluation; Benchmarking; Reliability; Validity; Agreement; Sensitivity; Specificity; Precision; Recall; Signal analysis; Pattern recognition; Event detection; EEG microarchitecture; EEG features; Sleep Spindles
11.  Nocturnal Rapid Eye Movement Sleep Latency for Identifying Patients With Narcolepsy/Hypocretin Deficiency 
JAMA neurology  2013;70(7):891-902.
Narcolepsy, a disorder associated with HLA-DQB1*06:02 and caused by hypocretin (orexin) deficiency, is diagnosed using the Multiple Sleep Latency Test (MSLT) following nocturnal polysomnography (NPSG). In many patients, a short rapid eye movement sleep latency (REML) during the NPSG is also observed but not used diagnostically.
To determine diagnostic accuracy and clinical utility of nocturnal REML measures in narcolepsy/hypocretin deficiency.
Observational study using receiver operating characteristic curves for NPSG REML and MSLT findings (sleep studies performed between May 1976 and September 2011 at university medical centers in the United States, China, Korea, and Europe) to determine optimal diagnostic cutoffs for narcolepsy/hypocretin deficiency compared with different samples: controls, patients with other sleep disorders, patients with other hypersomnias, and patients with narcolepsy with normal hypocretin levels. Increasingly stringent comparisons were made. In a first comparison, 516 age- and sex-matched patients with narcolepsy/hypocretin deficiency were selected from 1749 patients and compared with 516 controls. In a second comparison, 749 successive patients undergoing sleep evaluation for any sleep disorders (low pretest probability for narcolepsy) were compared within groups by final diagnosis of narcolepsy/hypocretin deficiency. In the third comparison, 254 patients with a high pretest probability of having narcolepsy were compared within group by their final diagnosis. Finally, 118 patients with narcolepsy/hypocretin deficiency were compared with 118 age- and sex-matched patients with a diagnosis of narcolepsy but with normal hypocretin levels.
Sensitivity and specificity of NPSG REML and MSLT as diagnostic tests for narcolepsy/hypocretin deficiency. This diagnosis was defined as narcolepsy associated with cataplexy plus HLA-DQB1*06:02 positivity (no cerebrospinal fluid hypocretin-1 results available) or narcolepsy with documented low (≤110 pg/mL) cerebrospinal fluid hypocretin-1 level.
Short REML (≤15 minutes) during NPSG was highly specific (99.2% [95% CI, 98.5%–100.0%] of 516 and 99.6% [95% CI, 99.1%–100.0%] of 735) but not sensitive (50.6% [95% CI, 46.3%–54.9%] of 516 and 35.7% [95% CI, 10.6%–60.8%] of 14) for patients with narcolepsy/hypocretin deficiency vs population-based controls or all patients with sleep disorders undergoing a nocturnal sleep study (area under the curve, 0.799 [95% CI, 0.771–0.826] and 0.704 [95% CI, 0.524–0.907], respectively). In patients with central hypersomnia and thus a high pretest probability for narcolepsy, short REML remained highly specific (95.4% [95% CI, 90.4%–98.3%] of 132) and similarly sensitive (57.4% [95% CI, 48.1%–66.3%] of 122) for narcolepsy/hypocretin deficiency (area under the curve, 0.765 [95% CI, 0.707–0.831]). Positive predictive value in this high pretest probability sample was 92.1% (95% CI, 83.6%–97.0%).
Among patients being evaluated for possible narcolepsy, short REML (≤15 minutes) at NPSG had high specificity and positive predictive value and may be considered diagnostic without the use of an MSLT; absence of short REML, however, requires a subsequent MSLT.
PMCID: PMC4170796  PMID: 23649748
12.  The Impact of Obesity on Oxygen Desaturation during Sleep-disordered Breathing 
Rationale: Obesity increases the risk and severity of sleep-disordered breathing. The degree to which excess body weight contributes to blood oxygen desaturation during hypopneic and apneic events has not been comprehensively characterized.
Objectives: To quantify the association between excess body weight and oxygen desaturation during sleep-disordered breathing.
Methods: A total of 750 adult participants in the Wisconsin Sleep Cohort Study were assessed for body mass index (BMI) (kg/m2) and sleep-disordered breathing. The amount of SaO2, duration, and other characteristics of 37,473 observed breathing events were measured during polysomnography studies. A mixed-effects linear regression model estimated the association of blood oxygen desaturation with participant-level characteristics, including BMI, gender, and age, and event-level characteristics, including baseline SaO2, change in Vt, event duration, sleep state, and body position.
Measurements and Main Results: BMI was positively associated with oxygen desaturation severity independent of age, gender, sleeping position, baseline SaO2, and event duration. BMI interacted with sleep state such that BMI predicted greater desaturation in rapid eye movement (REM) sleep than in non-REM sleep. Each increment of 10 kg/m2 BMI predicted a 1.0% (SE, 0.2%) greater mean blood oxygen desaturation for persons in REM sleep experiencing hypopnea events associated with 80% Vt reductions.
Conclusions: Excess body weight is an important predictor of the severity of blood oxygen desaturation during apnea and hypopnea events, potentially exacerbating the impact of sleep-disordered breathing in obese patients.
PMCID: PMC2778152  PMID: 19644043
sleep apnea; overweight; hypoxia
13.  Perceived neighborhood quality, sleep quality, and health status: Evidence from the Survey of the Health of Wisconsin 
Why does living in a disadvantaged neighborhood predict poorer mental and physical health? Recent research focusing on the Southwestern United States suggests that disadvantaged neighborhoods favor poor health, in part, because they undermine sleep quality. Building on previous research, we test whether this process extends to the Midwestern United States. Specifically, we use cross-sectional data from the Survey of the Health of Wisconsin (SHOW), a statewide probability sample of Wisconsin adults, to examine whether associations among perceived neighborhood quality (e.g., perceptions of crime, litter, and pleasantness in the neighborhood) and health status (overall self-rated health and depression) are mediated by overall sleep quality (measured as self-rated sleep quality and physician diagnosis of sleep apnea). We find that perceptions of low neighborhood quality are associated with poorer self-rated sleep quality, poorer self-rated health, and more depressive symptoms. We also observe that poorer self-rated sleep quality is associated with poorer self-rated health and more depressive symptoms. Our mediation analyses indicate that self-rated sleep quality partially mediates the link between perceived neighborhood quality and health status. Specifically, self-rated sleep quality explains approximately 20% of the association between neighborhood quality and self-rated health and nearly 19% of the association between neighborhood quality and depression. Taken together, these results confirm previous research and extend the generalizability of the indirect effect of perceived neighborhood context on health status through sleep quality.
PMCID: PMC3733364  PMID: 22901794
Sleep; Sleep quality; Neighborhood context; Neighborhood quality; Self-rated health; Depression; Wisconsin; USA
14.  Sleep-disordered breathing and retinal microvascular diameter 
Atherosclerosis  2012;226(1):124-128.
Sleep-disordered breathing (SDB) is an emerging risk factor for cardiovascular disease (CVD). Microvascular dysfunction has been proposed as a potential mechanism in the pathogenesis of CVD in SDB. The retinal vasculature offers a unique opportunity to investigate the systemic effects of microvascular dysfunction as it can be viewed non-invasively and is also structurally and functionally similar to microvasculature elsewhere in the body. We therefore examined the association between SDB and retinal microvascular diameter after adjusting for major confounders.
We examined n=476 participants from the Wisconsin Sleep Cohort Study. SDB was characterized using the apnea-hypopnea index (AHI) as <5 events/hr, 5-14.9 events/hr, and ≥15 events/hr. Outcomes of interest included the presence of retinal arteriolar narrowing (mean retinal arteriolar diameter <141.0 um) and retinal venular widening (mean venular diameter >223.0 um).
Higher AHI was found to be positively associated with retinal venular dilatation, independent of body mass index, hypertension, diabetes, and lipid levels. Compared to an AHI of <5 events/hr (referent), the multivariable-adjusted odds ratio of retinal venular widening for an AHI of 5-14.9 events/hr was 1.31(0.75-2.28) and for an AHI of >15 events/hr was 2.08 (1.03-2.16); p-trend=0.045. In contrast, there was no association between AHI and retinal arteriolar narrowing (p-trend=0.72).
Higher AHI, a marker of SDB, was positively associated with wider retinal venules, independent of age, gender, BMI, hypertension, diabetes, and lipid levels. These data suggest that the association of SDB with cardiovascular disease may be mediated, in part, by microvasculature.
PMCID: PMC3529805  PMID: 23137824
SDB; retinal arteriolar diameter; AHI
15.  Aging reduces the association between sleepiness and sleep-disordered breathing 
To investigate age-related changes in sleepiness symptoms associated with sleep disordered breathing (SDB).
Wisconsin Sleep Cohort participants were assessed with polysomnography, Epworth Sleepiness Scale (ESS) and Multiple Sleep Latency Test (MSLT). SDB was defined as an apnea/hypopnea index≥15 events/hour, sleepiness as ESS≥10 and MSLT≤5 minutes. Odds ratios were calculated using generalized estimating equations associating sleepiness with SDB, and conditional logistic regression examining changes in longitudinal sleepiness status (ESS only). Models were, a priori, stratified by gender.
ESS was measured in 1281 participants and MSLT in 998, at multiple time points (ESS n=3695; MSLT n=1846). Significant interactions were found between SDB and age in men, but not women. The odds ratios (OR) modeled for sleepiness in a 40 year old male with SDB were significant, compared to a male without SDB (OR: ESS 2.1; MSLT 2.9); however, these associations were not significant at 60 years. The within-subject odds ratio for sleepiness was also significant at 40 years (OR: 3.4), but not at 60 years.
The age-related reductions in the association between sleepiness and SDB may have clinical implications for the diagnosis and treatment of SDB in older people since sleepiness is often used as a therapeutic marker.
PMCID: PMC3608395  PMID: 22241742
Sleep disordered breathing; Obstructive sleep apnea; Aging; Sleepiness
16.  Sleep-disordered Breathing and Cancer Mortality 
Rationale: Sleep-disordered breathing (SDB) has been associated with total and cardiovascular mortality, but an association with cancer mortality has not been studied. Results from in vitro and animal studies suggest that intermittent hypoxia promotes cancer tumor growth.
Objectives: The goal of the present study was to examine whether SDB is associated with cancer mortality in a community-based sample.
Methods: We used 22-year mortality follow-up data from the Wisconsin Sleep Cohort sample (n = 1,522). SDB was assessed at baseline with full polysomnography. SDB was categorized using the apnea-hypopnea index (AHI) and the hypoxemia index (percent sleep time below 90% oxyhemoglobin saturation). The hazards of cancer mortality across levels of SDB severity were compared using crude and multivariate analyses.
Measurements and Main Results: Adjusting for age, sex, body mass index, and smoking, SDB was associated with total and cancer mortality in a dose–response fashion. Compared with normal subjects, the adjusted relative hazards of cancer mortality were 1.1 (95% confidence interval [CI], 0.5–2.7) for mild SDB (AHI, 5–14.9), 2.0 (95% CI, 0.7–5.5) for moderate SDB (AHI, 15–29.9), and 4.8 (95% CI, 1.7–13.2) for severe SDB (AHI ≥ 30) (P-trend = 0.0052). For categories of increasing severity of the hypoxemia index, the corresponding relative hazards were 1.6 (95% CI, 0.6–4.4), 2.9 (95% CI, 0.9–9.8), and 8.6 (95% CI, 2.6–28.7).
Conclusions: Our study suggests that baseline SDB is associated with increased cancer mortality in a community-based sample. Future studies that replicate our findings and look at the association between sleep apnea and survival after cancer diagnosis are needed.
PMCID: PMC3406081  PMID: 22610391
cancer; cohort study; mortality; obstructive sleep apnea; sleep-disordered breathing
17.  Exercise is associated with a reduced incidence of sleep-disordered breathing 
The American Journal of Medicine  2012;125(5):485-490.
The effect of exercise on sleep-disordered breathing is unknown. While diet and weight loss have been shown to reduce the severity of sleep-disordered breathing, it is unclear whether exercise has an independent effect.
A population-based longitudinal epidemiologic study of adults measured the association between exercise and incidence and severity of sleep-disordered breathing. Hours of weekly exercise were assessed by two mailed surveys (1988 and 2000). Sleep-disordered breathing was assessed by 18-channel in-laboratory polysomnography at baseline and at follow up.
Associations were modeled using linear and logistic regression, adjusting for body mass index, age, sex, and other covariates. Hours of exercise were associated with reduced incidence of mild (Odds Ratio = 0.76, p= 0.011) and moderate (Odds Ratio = 0.67, p= 0.002) sleep-disordered breathing. Also a decrease in exercise duration was associated with worsening sleep-disordered breathing, as measured by the apnea-hypopnea index, AHI (ß = 2.368, p= 0.048). Adjustment for body mass index attenuated these effects.
Exercise is associated with a reduced incidence of mild and moderate sleep-disordered breathing and decreasing exercise is associated with worsening of sleep-disordered breathing. The effect of exercise on sleep-disordered breathing appears to be largely, but perhaps not entirely, mediated by changes in body habitus.
PMCID: PMC3339801  PMID: 22482846
Exercise; Sleep Apnea
18.  β2 adrenergic receptor polymorphisms and nocturnal blood pressure dipping status in the Wisconsin Sleep Cohort Study 
Non-dipping nocturnal blood pressure (BP) is associated with target organ damage and cardiovascular disease. We hypothesized that β1- and β2-AR-associated SNPs would associate with non-dipping BP patterns. Participants (N=497, age range 30–74 years, 40% female) of the Wisconsin Sleep Cohort Study with at least one ambulatory BP monitoring test were included. Non-dipping was defined as less than a 10% dip in sleep BP compared to wake BP. Dipping ratios were calculated as sleep/wake BP. Single nucleotide polymorphisms in the β1-AR (rs7076938, tagging for Gly389Arg) and β2-AR (rs17778257 and rs2400707, tagging for Arg16Gly and Gln27Glu) were selected. β2-AR SNP rs2400707 A-positive subjects (tagging for Glu27) had higher systolic and diastolic dipping ratios in a dose-response fashion. Systolic dipping ratios were: GG=0.846; AG=0.854; AA=0.861 (p-trend=0.015). Diastolic dip ratios were: GG=0.807; AG=0.815; AA=0.824 (p-trend=0.026). The β2-AR rs17778257/rs2400707 A/A haplotype was associated with dipping ratios and systolic non-dipping status (non-dipping OR 2.0 [1.0, 3.8] for A/A versus A/G). Results were similar when models included participants on antihypertensive medications. Higher dipping ratios indicating a lack of nocturnal BP dipping are associated with β2-AR polymorphisms. Nocturnal dipping patterns may be modulated by β2-AR polymorphisms.
PMCID: PMC3071556  PMID: 21414566
single nucleotide polymorphisms; sympathetic nervous system; ambulatory blood pressure
19.  Effects of Sleep-disordered Breathing on Cerebrovascular Regulation 
Rationale: Cerebrovascular regulation is impaired in patients with moderate to severe obstructive sleep apnea; however, it is unknown whether this impairment exists in individuals with less severe sleep-disordered breathing.
Objectives: To test the hypothesis that cerebrovascular responses to hypercapnia are attenuated in a nonclinical population-based cohort.
Methods: A rebreathing test that raised end-tidal CO2 tension by 10 mm Hg was performed during wakefulness in 373 participants of the Wisconsin Sleep Cohort.
Measurements and Main Results: We measured cerebral flow velocity (transcranial Doppler ultrasound); heart rate (electrocardiogram); blood pressure (photoplethysmograph); ventilation (pneumotachograph); and end-tidal CO2 (expired gas analysis). Cerebrovascular CO2 responsiveness was quantified as the slope of the linear relationship between flow velocity and end-tidal CO2 during rebreathing. Linear regression analysis was performed using cerebrovascular CO2 responsiveness as the outcome variable. Main independent variables were the apnea–hypopnea index and the mean level of arterial oxygen saturation during sleep. We observed a positive correlation between cerebrovascular CO2 responsiveness and the mean level of oxygen saturation during sleep that was statistically significant in unadjusted analysis and after adjustment for known confounders and the increase in arterial pressure during rebreathing. Each 5% decrease in SaO2 during sleep predicted a decrease in cerebrovascular reactivity of 0.4 ± 0.2 cm/second/mm Hg PETCO2. In contrast, the negative correlation between cerebrovascular CO2 responsiveness and apnea–hypopnea index was statistically significant only in the unadjusted analysis.
Conclusions: Hypercapnic vasodilation in the cerebral circulation is blunted in individuals with sleep-disordered breathing. This impairment is correlated with hypoxemia during sleep.
PMCID: PMC3029932  PMID: 20639438
sleep apnea syndromes; cerebrovascular circulation; blood flow velocity; hypercapnia; endothelial function
20.  Prospective Associations of Insomnia Markers and Symptoms With Depression 
American Journal of Epidemiology  2010;171(6):709-720.
Whether insomnia, a known correlate of depression, predicts depression longitudinally warrants elucidation. The authors examined 555 Wisconsin Sleep Cohort Study participants aged 33–71 years without baseline depression or antidepressant use who completed baseline and follow-up overnight polysomnography and had complete questionnaire-based data on insomnia and depression for 1998–2006. Using Poisson regression, they estimated relative risks for depression (Zung scale score ≥50) at 4-year (average) follow-up according to baseline insomnia symptoms and polysomnographic markers. Twenty-six participants (4.7%) developed depression by follow-up. Having 3–4 insomnia symptoms versus none predicted depression risk (age-, sex-, and comorbidity-adjusted relative risk (RR) = 3.2, 95% confidence interval: 1.1, 9.6). After multiple adjustments, frequent difficulty falling asleep (RR = 5.3, 95% confidence interval: 1.1, 27.9) and polysomnographically assessed (upper or lower quartiles) sleep latency, continuity, and duration (RRs = 2.2–4.7; P’s ≤ 0.05) predicted depression. Graded trends (P-trend ≤ 0.05) were observed with increasing number of symptoms, difficulty falling asleep, and difficulty returning to sleep. Given the small number of events using Zung ≥50 (depression cutpoint), a limitation that may bias multivariable estimates, continuous depression scores were analyzed; mean values were largely consistent with dichotomous findings. Insomnia symptoms or markers increased depression risk 2.2- to 5.3-fold. These results support prior findings based on self-reported insomnia and may extend similar conclusions to objective markers. Heightened recognition and treatment of insomnia may prevent subsequent depression.
PMCID: PMC2842222  PMID: 20167581
depression; polysomnography; prospective studies; sleep; sleep initiation and maintenance disorders
21.  The Survey of the Health of Wisconsin (SHOW), a novel infrastructure for population health research: rationale and methods 
BMC Public Health  2010;10:785.
Evidence-based public health requires the existence of reliable information systems for priority setting and evaluation of interventions. Existing data systems in the United States are either too crude (e.g., vital statistics), rely on administrative data (e.g., Medicare) or, because of their national scope (e.g., NHANES), lack the discriminatory power to assess specific needs and to evaluate community health activities at the state and local level. This manuscript describes the rationale and methods of the Survey of the Health of Wisconsin (SHOW), a novel infrastructure for population health research.
The program consists of a series of independent annual surveys gathering health-related data on representative samples of state residents and communities. Two-stage cluster sampling is used to select households and recruit approximately 800-1,000 adult participants (21-74 years old) each year. Recruitment and initial interviews are done at the household; additional interviews and physical exams are conducted at permanent or mobile examination centers. Individual survey data include physical, mental, and oral health history, health literacy, demographics, behavioral, lifestyle, occupational, and household characteristics as well as health care access and utilization. The physical exam includes blood pressure, anthropometry, bioimpedance, spirometry, urine collection and blood draws. Serum, plasma, and buffy coats (for DNA extraction) are stored in a biorepository for future studies. Every household is geocoded for linkage with existing contextual data including community level measures of the social and physical environment; local neighborhood characteristics are also recorded using an audit tool. Participants are re-contacted bi-annually by phone for health history updates.
SHOW generates data to assess health disparities across state communities as well as trends on prevalence of health outcomes and determinants. SHOW also serves as a platform for ancillary epidemiologic studies and for studies to evaluate the effect of community-specific interventions. It addresses key gaps in our current data resources and increases capacity for etiologic, applied and translational population health research. It is hoped that this program will serve as a model to better support evidence-based public health, facilitate intervention evaluation research, and ultimately help improve health throughout the state and nation.
PMCID: PMC3022857  PMID: 21182792
22.  Sleep Disordered Breathing and Metabolic Syndrome 
Sleep disordered breathing (SDB) has been associated with cardiovascular disease, hypertension, and insulin resistance. This article examines the association between SDB and the prevalence of metabolic syndrome (MS) in a community-based sample.
A subset of participants in the Wisconsin Sleep Cohort Study (N=546) participated in an ancillary study to measure vascular and metabolic function. SDB was characterized using the apnea-hypopnea index (AHI) obtained in the polysomnography study closest to the collection of the metabolic measures. MS was defined using the National Cholesterol Education Program definition, and the homeostasis model assessment method (HOMA) was used to characterize insulin resistance.
SDB was significantly correlated with insulin resistance (Spearman r correlation between AHI and HOMA=0.30, P<0.0001). Compared with those without SDB (AHI <5), the age-sex-adjusted odds ratios of MS associated with mild (AHA 5-14.9) and moderate/severe SDB (AHI >15 or CPAP) were 4.0 (95% CI 2.6, 6.3) and 5.3 (95% CI 3.2, 8.8), respectively. Additional adjustment for markers of sympathetic or neuroendocrine activation (urinary norepinephrine, cortisol, heart rate variability) did not materially alter these estimates. These associations were weaker but remained statistically significant after adjusting for body mass index.
SDB might be considered an integral component of MS.
PMCID: PMC2873189  PMID: 19743760
23.  Burden of Sleep Apnea: Rationale, Design, and Major Findings of the Wisconsin Sleep Cohort Study 
Untreated sleep apnea is a prevalent but treatable condition of breathing pauses during sleep. With approximately 15% of the US population affected, understanding of the total health burden is necessary to guide policy, population initiatives, and clinical practice to reduce the prevalence of this condition.
To outline the history and need for a population approach to understanding sleep apnea and provide a review of the first longitudinal population study of this disorder.
Data Source
The results of cross-sectional and longitudinal data from 1500 participants in the Wisconsin Sleep Cohort, initiated 2 decades ago, illustrate the population burden of sleep apnea.
The prevalence of sleep apnea is increasing with trends of increased obesity. Prospective findings from 4- to 15-year follow-up data indicate untreated sleep apnea predicts increased blood pressure, hypertension, stroke, depression, and mortality.
The high prevalence of untreated sleep apnea and links to serious morbidity and mortality underscore the population burden of this condition and the need for greater clinical recognition and strategies to reduce prevalence.
PMCID: PMC2858234  PMID: 19743755

Results 1-23 (23)