Faculty Bibliography

Introduction: Previous research suggests that too little or too much sleep time in adults can have negative consequences on mortality, health, mood and cognitive outcomes. Most of these studies have measured sleep subjectively. In the present study we explored how average or long sleep measured objectively with actigraphy in older adults is associated with cognitive function. We hypothesized that long sleepers would have worse cognitive performance than average sleepers. Methods: As part of a larger longitudinal study, we measured total sleep time among 72 healthy older adults (mean age = 65.01, range = 60-77 years old, 63.9% were female) using actigraphy and sleep diaries. They were classified as average (6-7.25 h in bed) or long sleepers (8-9.25 h in bed). At baseline, we measured set shifting, visual attention and inhibition among 69 participants using the Stroop Task and the Trail Making Test. Results: Stroop Task: N = 69 participants completed this task at baseline. Completion time significantly differed (p < 0.05) between average (N = 39, 103.40 +/- 25.90 seconds) and long sleepers (N = 30, 117.61 +/- 30.74 seconds) with a moderate corresponding effect size (Cohen's d = 0.50). We found no significant difference (p > 0.5) between accuracy of average (4.74 +/- 6.63 errors) and long sleepers (3.73 +/- 5.52 errors). Trail Making Test: N = 64 participants completed this task at baseline. We found no significant difference (p > 0.9) in completion time between average (N = 35, 80.25 +/- 39.88 seconds) and long sleepers (N = 29, 79.87 +/- 30.77 seconds) and no significant difference (p > 0.65) between accuracy of average (0.74 +/- 0.98 errors) and long sleepers (0.86 +/- 1.19 errors). Conclusion: We found that longer sleep among older adults was associated with slower completion time on a task that requires inhibition of an automatic response, the Stroop Task, but that there were no significant differences on a task that requires set shifting and visual attention, the Trail Making Test

Introduction: Sleep duration has been inconsistently associated with elevated body mass index (BMI) in many populations. The Modeling the Epidemiologic Transition Study (METS), provides an excellent opportunity to assess these associations among populations of African origin at different levels of social and economic development. Methods: METS enrolled 500 young adults, 25-45 years, from each of 5 study sites: rural Ghana, urban South Africa, Seychelles, urban Jamaica and suburban U.S. Anthropometrics and self-reported sleep duration data were collected. Multivariate regression models were used to assess associations between habitual sleep duration and markers of obesity (BMI > 30 kg/m²) using aggregated data (using dummy site variables; n = 2,500), as well as with data from each site individually (n = 500 per analysis). Results: The mean (+/- SD) age was 34.7 (6.2) years. Among men, mean BMI ranged from 22.2 +/- 2.7 to 29.7 +/- 7.5 and among women it ranged from 25.5 +/- 5.2 and 34.1 +/- 8.8 in Ghana and the U.S., respectively. Percent body fat, fat mass, fat-free mass and waist and hip circumferences followed the same general pattern, lowest in Ghana and highest in the U.S. Mean sleep duration was shortest in the US (6.7 +/- 1.4 hours), intermediate in Seychelles (7.2 +/- 1.3), Jamaica (7.3 +/- 1.8), and Ghana (7.9 +/- 1.5) and longest in South Africa (10.3 +/- 1.7; p < 0.001), for both men and women. In multivariate regressions, adjusting for sex, age and site, sleep was significantly inversely associated with BMI, fat mass, fat-free mass, waist circumference and hip circumference (all p < 0.001). When site-specific regressions were conducted, results remained statistically significant across all sites only for fat-free mass (all sites p < 0.05). Conclusion: Sleep duration varied significantly between participants in South Africa and the other 4 METS study sites. In each and across all sites, fat-free mass was consistently more strongly associated with sleep duration than other indicators of obesity, warranting further investigation

Introduction: Clinical studies have indicated linkages between sleep duration and C-reactive protein (CRP), a stable inflammatory marker of cardiovascular disease. The present study explored effects of short (8 hrs) sleep durations, referenced to healthy sleep (7-8 hours), on CRP levels among participants in the Modeling the Epidemiologic Transition Study (METS). Methods: We conducted a multi-site comparative study of communities representing a broad range of social and economic development, defined by the UN Human Development Index (HDI): Ghana as low middle HDI country, South Africa as middle, Jamaica and Seychelles as high, and U.S.A. as very high HDI. Participants were predominantly of African descent (n = 1,276; ages 25-44; 50%) female). Sociodemo-graphic and anthropometric data were obtained at outpatient community-based clinics. Individuals were excluded if they had infectious diseases (e.g. HIV-positive), were pregnant/lactating, or had conditions preventing normal physical activities. Results: Of the sample, 54.9% were overweight/obese; 11.7%, hypertension; 2.2%), diabetes; and 4.7, dyslipidemia. Prevalence of short and long sleep durations varied by site. Compared with individuals who reported sleeping 7-8 hours, the U.S. had the highest rate of short sleepers (43.5%), while South Africa had the highest rate of long sleepers (86.5%), X2 = 69.4; p < 0.001. Likewise, CRP levels varied by site (US = 5.9 +/- 0.5, South Africa = 7.6 +/- 0.7, Ghana = 4.7 +/- 0.6, Jamaica = 4.1 +/- 0.3, and Seychelles = 3.0 +/- 0.2; F = 12.1, p < 0.001); values represent means and standard errors. GLM analysis, adjusting effects of age, sex, BMI and site, showed that short sleep did not have a significant effect on CRP Rather, long sleep had a significant effect on CRP (F = 10.5, p < 0.001). CRP was also affected by sex (F = 11.3, p < 0.001), BMI, (F = 8.7, p < 0.001) and site (F = 9.8, p < 0.001), but not by age. Conclusion: Findings are consistent with experimental studies showing effects of sleep on CRP, although long sleep, rather than, short sleep affected CRP concentrations. Site-specific differences in sleep durations and CRP levels are important, warranting further investigation

Introduction: Short and long sleep duration are an important public health burden in the United States. They are influenced by race/ethnicity and socioeconomic status. Little is known about the relationships between psychological health and short and long sleep across race/ethnicity. Our study examined the racial/ethnic influence on the relationship between psychological distress and sleep duration. Methods: Data from the 2009 National Health Interview Survey (NHIS), N = 27,731 participants ages > 18 years, were analyzed to investigate the associations of psychological distress with inadequate sleep duration, adjusting for socio-demographic factors, health risk behaviors, and chronic diseases. Short sleep was coded as 8 hours. Psychological distress (PD), based on Kessler's 6 scale, assessed the frequency of feeling sad, nervous, restless, hopeless, worthless, and burdened over a 30-day period. Scores range from 0 to 24 and scores > 13 likely indicate serious mental illness. Results: Of the sample, 51.6% were female; 76.2%, White and 15.6%, Black/African-American, with a mean age of 35.79 +/- 22.4 yrs. Of the sample, 8.1%) of Blacks vs. 7.1% of Whites reported PD. Logistic regression analysis indicated that blacks and whites with PD have similar odds of reporting short sleep (Blacks: OR = 2.33, p < 0.05 and Whites: OR = 2.36, p < 0.05). However, different odds for long sleep were observed (Blacks: OR = 1.23, p < 0.05 and Whites: OR = 1.63, p < 0.05). These analyses adjusted for demographic, health risk behaviors, and chronic diseases. We also found discrepancies in the predictive model. For Whites, gender, marital status, family income, body mass index, arthritis, diabetes, hypertension, heart condition and PD predicted short sleep. For Blacks, only age, family income, hypertension and PD predicted short sleep. Conclusion: Psychological distress was the strongest predictor of short and long sleep for both groups. PD and short and long sleep were more prevalent among blacks than among whites. Our study underscored the significant role of PD in racial/ethnic sleep disparities

Introduction: Individuals with chronic fatigue syndrome (CFS) frequently show abnormal and unrefreshing sleep patterns, in addition to chronic malaise, depressed mood, body pain, sore throat, and lifestyle restrictions. Using data from the National Health Interview Survey (NHIS), we hypothesized that among participants reporting CFS, higher frequency of moderate exercise would be associated with fewer missed workdays due to illness. Methods: NHIS is a cross-sectional household interview survey, using a multistage area probability design. Data from participants in the 2008 NHIS emanated from face-to-face interviews with trained interviewers from the U.S. Census Bureau. Respondents provided sociode-mographic and physician-diagnosed chronic conditions. Our analysis focused on those responding to the questions: "Have you ever had... chronic fatigue syndrome", and "how often per week do you do light or moderate leisure-time physical activities?" Student's T-test was used for mean comparisons, and ANOVA assessed interaction effects on continuous variables. Analyses were performed using SAS 9.3. Results: A total of 21,733 individuals provided valid data. The male/female ratio was 0.38:1. Of the sample, 78% were white; 16%, black; and 4%), Asian. The average age for respondents with CFS was > those without (55.0 +/- 15.4 years vs. 48.0 +/- 18.1 years, p < 0.0001). The prevalence of CFS was 2.7%). Among respondents with CFS, those reporting frequent exercise (> 2X moderate exercise weekly) had lower sleep duration (7.0 +/-1.7 hours) than those who did not (7.4 +/-1.9 hours); NS. Results of ANOVA showed that among respondents with CFS, those with higher exercise frequency (> 2X weekly) had lower average number of missed workdays (6 days), compared to those with lower exercise frequency (< 2X weekly [15 days] (F = 11.56, p < 0.001). Conclusion: Results support our hypothesis that among individuals with CFS those who exercised more frequently had lower rates of missed workdays due to illness, compared to those who exercised less. Decreased exercise was linked to absenteeism during the year they were assessed

Introduction: Big data and complex system analyses provide unique opportunities to quantify dynamic omnidirectional interactions among multiple factors that impact diseases and health outcomes. Applying this type of analysis to sleep data is crucial, as sleep is linked to a host of chronic medical conditions. Methods: Analysis was based on the 2004-2013 National Health Interview Survey (N = 231,111). We employed a machine-learning Bayesian Belief Network (BBN) to model the probabilistic relationships (independent and additive) of sleep duration and physical activity to stroke risk. Factors considered included demographic, behavioral, health/medical, and psychosocial as well as sleep duration (short, average, and long), and physical activity (leisurely walking/bicycling, slow swimming/dancing, and simple gardening activities). Results: Of the sample, 48.1% were < 45 years; 77.4% were White; 15.9%), Black/African American; and 45.1% reported less than $35K annually. Overall, the model had a precision index of 95.84%. Average sleepers (7-8 hours) were 25% (2.3% to 3%) less likely to experience a stroke. Respectively, long sleepers (> 8 hours) were 146% (3% to 75%) and short sleepers (< 7 hours) were 25% (3% to 3.74%) more likely to report a stroke. A model-based adaptive method evidenced that combined effect of health status, hypertension, heart condition, income, and alcohol consumption increased the likelihood from 3% to 90%. Healthy sleep (7-8 hours) and vigorous exercise (30-60 minutes) three to six times per week significantly decreased stroke risk. Using the observational inference technique, we developed idiosyncratic profiles of protective behaviors (i.e. minutes and frequency of moderate or vigorous exercise per week and short, average or long sleep) that reduced stroke risk. Conclusion: Utilization of BBN analysis is important, as it provides a more dynamic risk stratification system. Our findings revealed healthy sleep and exercise routines reduced stroke risk based on systematic iterations using multiple demographic, behavioral, health/medical, and psychosocial factors

Introduction: We assessed associations of sleep duration and socio-demographic factors with severe headaches/migraine. Methods: National Health Interview Survey (NHIS) data collected from 1997-2013 was utilized. NHIS applied a multistage area probability sampling design. Descriptive statistics were used to characterize the sample, and multivariate logistic regression model was used to test associations of sleep duration and socioeconomic factors with severe headaches/migraine. Results: Of 515,456 adults surveyed, the mean (+/- SEM) age was 54.3 +/- 0.016 ranging from 18 to 85 years; the mean body mass index (BMI) in kg/m² was 26.8 +/- 0.007 A greater proportion of women reported headaches compared to men (20.1% vs 9.5%, p < 0.001). Individuals with headaches were younger (42.2 +/- 0.05 vs. 48.1 +/- 0.02, p < 0.01) and had higher BMI (27.3 +/- 0.02 vs. 26.7 +/- 0.01, p < 0.01). Headaches were more common among short sleepers, < 7 hours (21.5%) and long sleepers, > 8 hours (15.7%), compared to those averaging 7-8 hours (12%), p < 0.01. Headaches were more common among blacks, compared to whites and Asians (16.5%, 15.4% and 10.9%, respectively), p < 0.01. Headaches were reported by individuals who were separated (23.1%), divorced (18.3%), never married individuals (16.8%,) married (14.6%) or 9 widowed (6%), p < 0.01. After adjusting for age, BMI and sleep duration, the odds ratio (OR) for headaches for married was 1.126 (95% CI = 1.093-1.159), p < 0.01; for widowed: OR was 1.28 (95% CI = 1.207-1.36), p < 0.01; for divorced: OR was 1.57 (95% CI = 1.52-1.63), p < 0.01 and for separated: OR was 1.85 (95% CI = 1.75-1.95), p < 0.01, using never married as a referent. Headaches were more common among individuals below (23.0%), compared to those above (14.8%) poverty level, p < 0.01. Conclusion: Both short and long sleep durations were associated with higher frequency of headaches. Female sex, increasing BMI and younger age were also associated with increased headaches. Compared to individuals who were never married, those of other marital status had increased odds of having headaches. Poverty level was significantly associated with increased headaches

Introduction: Resistant hypertension (RHTN) is an important condition affecting 3-29%) of the US population, albeit more common among blacks. We evaluated associations of RHTN with short sleep among blacks. Methods: Data came from the Metabolic Syndrome Outcome Study (MetSO), an NIH-funded cohort study characterizing metabolic syndrome (MetS) among blacks. Analysis was based on 883 patients (mean age: 62 +/- 14 years; female: 69.2%). MetS was defined according to criteria from the Adult Treatment Panel (ATP III). RHTN was defined as failure to achieve blood pressure goal (BP) of < 140/90 mm/Hg or < 130/80 mm/Hg among patients with diabetes or kidney disease when on maximal doses of a three-drug regimen. This also includes patients requiring more medications to achieve BP goal. Short sleep, derived from subjective reports, was defined as < 7 hours, referenced to healthy sleep (7-8 hours). OSA risk was assessed using the Apnea Risk Evaluation System (ARESTM); patients with a score > 6 were considered at high OSA risk, based on validated studies. Results: Most (90.4%) were overweight/obese; 61.4% had diabetes; 74.8%, dyslipidemia; 30.2%, heart disease; and 48% were at OSA risk. Overall, 92.6% had HTN, and 20.8% met criteria for RHTN. Analyses showed no significant difference in HTN prevalence comparing short (91.4%) and healthy sleepers (93.1%), but those with RHTN were more likely to be short sleepers (26.8% vs. 14.9%, p < 0.001). Based on logistic regression analysis, adjusting for effects of age, sex and medical comorbidities, patients with RHTN had increased odds of being short sleepers (OR = 1.90, 95% CI: 1.27-2.90, p = 0.002). Of interest, odds of being short sleepers among those at OSA risk were similar (OR = 1.92, 95% CI: 1.38-2.68, p< 0.001). Conclusion: Among blacks with metabolic syndrome, patients meeting criteria for RHTN showed a twofold greater likelihood of being short sleepers. Adjusted odds of short sleep were remarkably similar to those observed for patients at OSA risk

Introduction: Stress influences blood glucose control and cardiovascular risk factors, including hypertension, among individuals with type 2 diabetes. Evidence also shows that stress might be associated with type 1 diabetes. We examined associations of emotional distress and type 2 diabetes and evaluated interactions between sleep duration with emotional distress on diabetes risk. Methods: We used 2004-2013 NHIS dataset, which applied a multistage area probability sampling design. Diabetes was self-reported and the Kessler-6 (K6) scale was used to assess emotional distress; a score > 13 indicated distress. Descriptive statistics and logistic regression modeling were used to evaluate hypothesized relationships. Results: Of the 425,510 individuals surveyed, 53.0% were female; mean (+/- SEM) age and BMI were 35.3 +/- 0.02 years and 26.1 +/- 0.07 Kg/m², respectively. Prevalence of diabetes was 6.6%, with 56.0% being female. Individuals reporting diabetes were older (60.7 +/- 0.08 versus 35.1 +/- 0.03; p < 0.01) and had higher BMI (30.3 +/- 0.04 versus 26.7 +/- 0.01; p < 0.01). Prevalence of hypertension was higher among diabetics (72.0% versus 26%; p < 0.01). Of those with diabetes, 5.6% reported daily exercise, compared to 22.7% among non-diabetics, p < 0.01. Prevalence of dyslipidemia was also higher among diabetics (59.1%) versus 24.3%; p < 0.01). There was higher prevalence of diabetes among short sleepers [8 hrs] (10.9%), compared to healthy sleepers [7-8 hrs] (77%); p < 0.01). Individuals with diabetes had higher frequency of emotional distress (707% versus 3.3%; p < 0.01). Based on logistic regressions, emotional distress was associated with diabetes (OR = 1.45; 95% CI = 1.27-1.66; p < 0.05), after adjusting for diabetes risk factors: age, race, BMI, hypertension, dyslipidemia, physical activity, sleep duration, and marital, educational and poverty status. Conclusion: Our study indicates high risk of diabetes associated with emotional distress, even with adjustment for traditional diabetes risk factors. Further research is needed to delineate the pathophysiological factors underlying associations of diabetes with stress and to determine whether stress could induce diabetes

Introduction: The prevalence of short sleep (< 7 hours) has gradually increased over the last four decades, warranting an in-depth analysis of its influence on health outcomes. This study explored influences of body mass index (BMI), physical activity, and emotional distress on associations between short sleep and chronic diseases. Methods: Data for the present analysis came from the National Health Interview Survey, an ongoing nationally representative cross-sectional study of non-institutionalized US adults (> 18 years) from 2004-2013 (N = 911,773). They provided health data including physician-diagnosed hypertension, coronary heart disease, diabetes, stroke, kidney disease, cancer, and history of heart attack. We used the recommended criterion of > 150 minutes/week of moderate physical activity or > 75 minutes/week of vigorous to define physical activity and Kessler's 6 scales to measure emotional distress. Structural equation modeling was used to assess effects of physical activity, BMI, and emotional distress on relationships between short sleep and chronic diseases. Results: Analysis showed 51.6% of the sample was female; 76.2%, white; and 15.6%), black with a mean age of 35.79 +/- 22.4 yrs. Physical activity negatively mediated relationships between short sleep and cancer, stroke, coronary heart disease, heart attack, hypertension, and diabetes (path coefficient estimate = -0.053), (p < 0.001). BMI positively mediated relationships between short sleep and smoking, hypertension, and diabetes (point coefficient estimate = 0.828), (p < 0.001). Emotional distress also positively mediated relationships between short sleep and hypertension, diabetes and coronary heart disease (point coefficient estimate = 0.743), (p < 0.743). Adjusted covariates included age, race, gender, marital status, and income. Conclusion: Results are consistent with previous reports regarding associations between short sleep and chronic diseases. Of interest, emotional distress and increased BMI had significant effects on relationships between short sleep and chronic diseases. Increased physical activity however, was not associated with short sleep