Cognitive and functional performance and plasma biomarkers of early Alzheimer's disease in Down syndrome.

INTRODUCTION: People with Down syndrome (DS) have a 75% to 90% lifetime risk of Alzheimer's disease (AD). AD pathology begins a decade or more prior to onset of clinical AD dementia in people with DS. It is not clear if plasma biomarkers of AD pathology are correlated with early cognitive and functional impairments in DS, and if these biomarkers could be used to track the early stages of AD in DS or to inform inclusion criteria for clinical AD treatment trials. METHODS: This large cross-sectional cohort study investigated the associations between plasma biomarkers of amyloid beta (Aß)42/40, total tau, and neurofilament light chain (NfL) and cognitive (episodic memory, visual-motor integration, and visuospatial abilities) and functional (adaptive behavior) impairments in 260 adults with DS without dementia (aged 25-81 years). RESULTS: In general linear models lower plasma Aß42/40 was related to lower visuospatial ability, higher total tau was related to lower episodic memory, and higher NfL was related to lower visuospatial ability and lower episodic memory. DISCUSSION: Plasma biomarkers may have utility in tracking AD pathology associated with early stages of cognitive decline in adults with DS, although associations were modest. Highlights: Plasma Alzheimer's disease (AD) biomarkers correlate with cognition prior to dementia in Down syndrome.Lower plasma amyloid beta 42/40 was related to lower visuospatial abilities.Higher plasma total tau and neurofilament light chain were associated with lower cognitive performance.Plasma biomarkers show potential for tracking early stages of AD symptomology.

AT(N) biomarker profiles and Alzheimer's disease symptomology in Down syndrome.

INTRODUCTION: Down syndrome (DS) is a genetic cause of early-onset Alzheimer's disease (AD). The National Institute on Aging-Alzheimer's Association AT(N) Research Framework is a staging model for AD biomarkers but has not been assessed in DS. METHOD: Data are from the Alzheimer's Biomarker Consortium-Down Syndrome. Positron emission tomography (PET) amyloid beta (Aß; 15 mCi of [11 C]Pittsburgh compound B) and tau (10 mCi of [18 F]AV-1451) were used to classify amyloid (A) -/+ and tau (T) +/-. Hippocampal volume classified neurodegeneration (N) -/+. The modified Cued Recall Test assessed episodic memory. RESULTS: Analyses included 162 adults with DS (aged M = 38.84 years, standard deviation = 8.41). Overall, 69.8% of participants were classified as A-/T-/(N)-, 11.1% were A+/T-/(N)-, 5.6% were A+/T+/(N)-, and 9.3% were A+/T+/(N)+. Participants deemed cognitively stable were most likely to be A-T-(N)- and A+T-(N)-. Tau PET (T+) most closely aligning with memory impairment and AD clinical status. DISCUSSION: Findings add to understanding of AT(N) biomarker profiles in DS. HIGHLIGHTS: Overall, 69.8% of adults with Down syndrome (DS) aged 25 to 61 years were classified as amyloid (A)-/tau (T)-/neurodegeneration (N)-, 11.1% were A+/T-/(N)-, 5.6% were A+/T+/(N)-, and 9.3% were A+/T+/(N)+. The AT(N) profiles were associated with clinical Alzheimer's disease (AD) status and with memory performance, with the presence of T+ aligned with AD clinical symptomology. Findings inform models for predicting the transition to the prodromal stage of AD in DS.

Timing of Alzheimer's Disease by Intellectual Disability Level in Down Syndrome.

BACKGROUND: Trisomy 21 causes Down syndrome (DS) and is a recognized cause of early-onset Alzheimer's disease (AD). OBJECTIVE: The current study sought to determine if premorbid intellectual disability level (ID) was associated with variability in age-trajectories of AD biomarkers and cognitive impairments. General linear mixed models compared the age-trajectory of the AD biomarkers PET Aß and tau and cognitive decline across premorbid ID levels (mild, moderate, and severe/profound), in models controlling trisomy type, APOE status, biological sex, and site. METHODS: Analyses involved adults with DS from the Alzheimer's Biomarkers Consortium-Down Syndrome. Participants completed measures of memory, mental status, and visuospatial ability. Premorbid ID level was based on IQ or mental age scores prior to dementia concerns. PET was acquired using [11C] PiB for Aß, and [18F] AV-1451 for tau. RESULTS: Cognitive data was available for 361 participants with a mean age of 45.22 (SD = 9.92) and PET biomarker data was available for 154 participants. There was not a significant effect of premorbid ID level by age on cognitive outcomes. There was not a significant effect of premorbid ID by age on PET Aß or on tau PET. There was not a significant difference in age at time of study visit of those with mild cognitive impairment-DS or dementia by premorbid ID level. CONCLUSION: Findings provide robust evidence of a similar time course in AD trajectory across premorbid ID levels, laying the groundwork for the inclusion of individuals with DS with a variety of IQ levels in clinical AD trials.

Influence of the menopausal transition on polysomnographic sleep characteristics: a longitudinal analysis.

STUDY OBJECTIVES: To evaluate how change in menopausal status related to spectral analysis and polysomnographic measures of sleep characteristics. METHODS: The Study of Women's Health Across the Nation (SWAN) Ancillary Sleep Study evaluated sleep characteristics of 159 women who were initially pre- or early perimenopausal and repeated the assessment about 3½ years later when 38 were pre- or early perimenopausal, 31 late perimenopausal, and 90 postmenopausal. Participants underwent in-home ambulatory polysomnography for two to three nights. Average EEG power in the delta and beta frequency bands was calculated during NREM and REM sleep, and sleep duration, wake after sleep onset (WASO), and apnea hypopnea index (AHI) were based on visually-scored sleep. RESULTS: The women who transitioned to postmenopause had increased beta NREM EEG power at the second assessment, compared to women who remained pre-or early premenopausal; no other sleep measures varied by change in menopausal status. In multivariate models the associations remained; statistical controls for self-reported hot flashes did not explain findings. In secondary analysis, NREM beta power at the second assessment was greater among women who transitioned into the postmenopause after adjustments for initial NREM beta power. CONCLUSIONS: Sleep duration and WASO did not vary by menopause transition group across assessments. Consistent with prior cross-sectional analysis, elevated beta EEG power in NREM sleep was apparent among women who transitioned to postmenopause, suggesting that independent of self-reported hot flashes, the menopausal transition is associated with physiological hyperarousal during sleep.

Pathways connecting family socioeconomic status in adolescence and sleep continuity in adult Black and White men.

OBJECTIVE: To evaluate the roles of parenting and adolescent characteristics during ages 13 to 16 in connecting family socioeconomic status (SES) during adolescence with adult sleep in Black and White men. DESIGN: Longitudinal school-based community study beginning in 1987-1988 when participants were enrolled in the first or seventh grade. SETTING: Pittsburgh, PA. PARTICIPANTS: 291 men (54.4% Black, mean age = 33, SD = 2.5) participated in 2012-2014 in a week-long study of sleep measured by actigraphy and diary. MEASURES: In adolescence (ages 13-16), measures of family SES based on occupation, education, income and public assistance; parenting based on monitoring, positive expectations for future, warm parent-child relationship, and communication; and adolescent characteristics based on anxiety, hyperactivity/impulsivity, and peer rejection.  In adulthood, participant SES, minutes awake after sleep onset (WASO), duration, and diary-assessed sleep quality. RESULTS: Structural equation modeling confirmed significant indirect pathways: (1) low family SES in adolescence to negative parenting to low adult SES to greater WASO; (2) low family SES in adolescence to adolescent characteristics to low adult SES to greater WASO; (3) Black race to low family SES in adolescence to negative parenting to low adult SES to greater WASO; and (4) Black race to low family SES in adolescence to adolescent characteristics to adult SES to greater WASO. Similar models for duration and quality were not confirmed. CONCLUSIONS: Parenting and adolescent characteristics may have an indirect association with adult sleep continuity. Parenting and mental health interventions in adolescence may improve adult sleep.

Does midlife aging impact women's sleep duration, continuity, and timing?: A longitudinal analysis from the Study of Women's Health Across the Nation.

Our study objectives were to evaluate the age-related changes in actigraphy measures of sleep duration, continuity, and timing across 12 years in midlife women as they traversed the menopause, and to take into account factors affecting women's sleep that also change with age. Black, white, and Chinese women were recruited from the Study of Women's Health Across the Nation (SWAN) to participate in an ancillary sleep study on two occasions over 3 years apart and a third assessment 12 years after the first (N = 300, mean ages, 52, 55, and 64 at the three assessments). Women had at least four consecutive nights of actigraphy (95% with 7 nights) and sleep diaries, and self-reported sleep complaints measured at each time point. Partial correlations adjusted for time between assessments across the 12 years were significant and moderate in size (r's = .33-.58). PROC MIXED/GLIMMIX multivariate models showed that sleep duration increased over time; wake after sleep onset (WASO) declined, midpoint of sleep interval increased, and sleep latency and number of sleep complaints did not change between the first and third assessments. Blacks and whites had a greater increase in sleep duration than Chinese. Taken together, the results of this longitudinal study suggest that sleep may not worsen, in general, in midlife women. Perhaps, the expected negative effect of aging in midlife into early old age on sleep is overstated.

Racial/ethnic disparities in women's sleep duration, continuity, and quality, and their statistical mediators: Study of Women's Health Across the Nation.

STUDY OBJECTIVES: To describe racial/ethnic differences in sleep duration, continuity, and perceived sleep quality in postmenopausal women and to identify statistical mediators of differences in sleep characteristics. METHODS: Recruited from the observational Study of Women's Health Across the Nation (SWAN), 1,203 (548 white, 303 black, 147 Chinese, 132 Japanese, and 73 Hispanic; mean age 65 years, 97% postmenopausal) women participated in a week-long actigraphy and daily diary study in 2013-2015. Actigraphic measures of sleep duration and wake after sleep onset (WASO), and diary-rated sleep quality were averaged across the week. Candidate mediators included health-related variables; stress; and emotional well-being assessed up to 13 times across 18 years from baseline to sleep study. RESULTS: Whites slept longer than other groups; the significant mediators were concurrent financial hardship and increasing number of stressors for Hispanics or Japanese versus whites. Whites had less WASO than blacks and Hispanics; significant mediators were concurrent number of health problems, physical inactivity, waist circumference, vasomotor symptoms, number of life stressors, and financial hardship, and increasing number of health problems from baseline to sleep study. Whites reported better sleep quality than blacks, Chinese, and Japanese; significant mediators were concurrent physical inactivity, vasomotor symptoms, positive affect, and depressive symptoms. CONCLUSIONS: Sleep differences between blacks or Hispanics versus whites were mediated by health problems, number of stressors, and financial hardship, whereas sleep differences between Chinese or Japanese versus whites were mediated by emotional well-being. This is the first study using formal mediational approaches.

Depressive Symptoms During Childhood and Cardiovascular Risk Factors in Black and White Men.

OBJECTIVE: Depressive symptoms and major depression predict cardiovascular disease (CVD) and CVD risk factors in adulthood. Evidence regarding the role of depression in the development of CVD risk in youth is minimal. The study evaluated the prospective relationship of depressive symptoms in childhood and adolescence with adult CVD risk factors in black and white men. METHODS: Health behaviors and medical history were measured in 165 black and 146 white men (mean age = 32); a subset in the Pittsburgh area had a fasting blood draw to measure metabolic syndrome and inflammation. Adult CVD risk factors were related to depressive symptoms and childhood socioeconomic status (SES) prospectively measured annually from ages 7 to 16 years, followed by adjustments for adult SES and depressive symptoms. RESULTS: Men with higher depressive symptoms ages 7 to 16 smoked more cigarettes, B = 0.28 (standard error = 0.12), p = .015, and ate fewer servings of fruits and vegetables, B = -0.08 (0.04), p = .040, as adults. The association for smoking was independent of adult depressive symptoms (concurrent) and childhood and adult SES as well as race. Depressive symptoms during childhood were unrelated to the metabolic syndrome or biomarkers of inflammation in adulthood. CONCLUSIONS: Depressive symptoms in childhood may predict later adverse health behaviors in black and white men. No evidence was found for an association between childhood depressive symptoms with metabolic syndrome or inflammation markers at ages approximately 32 years. The nature of the sample and lack of measurement of depressive disorder diagnosis tempers the conclusions, and future research is needed to determine associations with biological measures at later life span phases.

Socioeconomic status in childhood predicts sleep continuity in adult Black and White men.

OBJECTIVES: Low socioeconomic status (SES) in childhood may be associated with sleep in adulthood. We evaluated the relationships between SES in childhood through adolescence and into adulthood and sleep in midlife men. DESIGN: Prospective assessment of SES in childhood and adulthood. SETTING: Population-based study of 139 Black and 105 White men enrolled since age 7 and evaluated for sleep characteristics at age 32. MEASUREMENTS: Actigraphy and diary measures of sleep duration, continuity, and quality for 1 week. Their parents reported their SES (a combination of educational attainment and occupational status) annually when the boys were ages 7 to 16. We estimated SES intercept (age 7) and slope (age 7 to 16) using M-Plus and conducted linear regression analyses using those values to predict adult sleep measures, adjusting for covariates. RESULTS: Men who had lower SES families at age 7, smaller increases in SES from ages 7 to 16, and lower SES in adulthood had more minutes awake after sleep onset. White men with greater increases in SES from ages 7 to 16 had shorter sleep. CONCLUSIONS: SES in childhood and improvement in SES through adolescence are related to sleep continuity in midlife men. To our knowledge, this is the first report using prospectively measured SES in childhood in relation to adult sleep.

Similarities and differences in estimates of sleep duration by polysomnography, actigraphy, diary, and self-reported habitual sleep in a community sample.

OBJECTIVES: To compare estimates of sleep duration defined by polysomnography (PSG), actigraphy, daily diary, and retrospective questionnaire and to identify characteristics associated with differences between measures. DESIGN: Cross-sectional. SETTING: Community sample. PARTICIPANTS: The sample consisted of 223 Black, White, and Asian middle- to older-aged men and women residing in the Pittsburgh, PA area. INTERVENTIONS: Not applicable. MEASUREMENTS: Two nights of in-home PSG; 9 nights of wrist actigraphy and sleep diaries; retrospective sleep questionnaires; and measures of sociodemographic, psychosocial, and adiposity characteristics. RESULTS: All measures of sleep duration differed significantly, with modest associations between PSG-assessed and retrospective questionnaire-assessed sleep duration. Individuals estimated their habitual sleep duration about 20-30 minutes longer by questionnaire and their prospective sleep diaries compared with both PSG- and actigraphy-assessed sleep duration. Persons reporting higher hostility had smaller associations between PSG-assessed sleep duration and other methods compared with those with lower hostility; those reporting more depressive symptoms and poorer overall health had smaller associations between actigraphy-assessed sleep duration and questionnaire and diary measures. Apnea-hypopnea index was not related to differences among estimates of sleep duration. CONCLUSIONS: PSG, actigraphy, diary, and retrospective questionnaire assessments yield different estimates of sleep duration. Hostility, depressive symptoms, and perceptions of poor health were associated with the magnitude of differences among some estimates. These findings may be useful in understanding the health consequences of short or long self-reported sleep duration and for guiding investigator decisions about choices of measures in specific populations.

Socioeconomic status and parenting during adolescence in relation to ideal cardiovascular health in Black and White men.

OBJECTIVE: American Heart Association (AHA) developed a new metric to evaluate ideal cardiovascular health based on optimal levels of 7 cardiovascular risk factors and health behaviors. We evaluated the relationships of parenting characteristics and academic achievement in adolescence in relation to ideal cardiovascular health in midlife men. METHOD: We measured cardiovascular risk factors in 171 Black and 136 White men and their ideal cardiovascular health score was constructed based on AHA guidelines. When the participants were 13-16 years old, annual measures of parent-child communication, positive relationship, parental monitoring, family cohesion, boys' involvement in family activities, and academic achievement were recorded and averaged. RESULTS: Confirmatory factor analysis of adolescent parenting measures revealed a single Parenting Composite. Multiple linear regressions showed a significant Race by Parenting Composite interaction term, ß = -.19, p = .03; better parenting was significantly related to more ideal cardiovascular health in Blacks only, ß = -.23, p = .004, which remained after adjustments for adolescent and adult socioeconomic status (SES). Academic achievement was related to ideal cardiovascular health, ß = -.13, but was no longer significant after controls for adult SES. Adult SES was a strong correlate of ideal cardiovascular health in Black and White men. CONCLUSIONS: Black men exposed to positive parenting during adolescence had more ideal cardiovascular health based on AHA guidelines. Improving academic achievement in adolescence may indirectly benefit adult cardiovascular health through improving adult SES. This is the first study of adolescent family predictors of the extent of ideal cardiovascular health. (PsycINFO Database Record

Bullying and Being Bullied in Childhood Are Associated With Different Psychosocial Risk Factors for Poor Physical Health in Men.

Bullying and being bullied in childhood are both linked with later adjustment problems. The impact of childhood bullying on risk for poor physical health in adulthood is understudied. Black and White men ( n = 305; mean age = 32.3 years) enrolled in the Pittsburgh Youth Study since the first grade underwent a comprehensive assessment of psychosocial, behavioral, and biological risk factors for poor health. Indices of bullying and being bullied were created by averaging annual ratings collected from participants and their caregivers when the participants were 10 to 12 years old. Results showed that being a bully in childhood was associated with greater stress and aggression and poorer health behaviors in adulthood, whereas being a victim of bullies in childhood was associated with lower socioeconomic resources, less optimism, and greater unfair treatment in adulthood. Unexpectedly, neither bullying nor being bullied in childhood was related to inflammation or metabolic syndrome. Bullying and being bullied in childhood were associated with distinct domains of psychosocial risk in adulthood that may later lead to poor physical health.

Temporal Relationships Between Napping and Nocturnal Sleep in Healthy Adolescents.

Many adolescents do not achieve the recommended 9 hr of sleep per night and report daytime napping, perhaps because it makes up for short nocturnal sleep. This article tests temporal relationships between daytime naps and nighttime sleep as measured by actigraphy and diary among 236 healthy high school students during one school week. Mixed model analyses adjusted for age, race, and gender demonstrated that shorter actigraphy-assessed nocturnal sleep duration predicted longer napping (measured by actigraphy and diary) the next day. Napping (by actigraphy and diary) predicted shorter nocturnal sleep duration and worse sleep efficiency that night measured by actigraphy. Diary-reported napping also predicted poorer self-reported sleep quality that night. Frequent napping may interfere with nocturnal sleep during adolescence.

Getting a Good Night's Sleep in Adolescence: Do Strategies for Coping With Stress Matter?

Getting a good night's sleep is challenging for adolescents because of early school start times and adolescents' substantial social and physical changes. We tested whether key indices of sleep health are associated with usual styles of coping with stress and interpersonal conflict in healthy black and white adolescents. Two hundred forty-two (57% female, 56% black) high school students completed daily sleep diaries, questionnaires, and actigraphy across a school week. Linear regression models tested associations, independent of race, gender, and other covariates. Students who reported using disengagement coping exhibited poor sleep health. They had shorter sleep duration, more fragmented sleep, delayed sleep, and increased daytime sleepiness. Unexpectedly, positive engagement coping was related to daytime sleepiness and delayed sleep, although not in models that included disengagement coping. Coping strategies may be an important influence on adolescent sleep. Future research should evaluate the antecedent-consequent relationships among coping, sleep, and stress.

Sleep duration during the school week is associated with C-reactive protein risk groups in healthy adolescents.

BACKGROUND: The prevalence of short sleep duration in adolescence and the relevance of early risk factors to cardiovascular disease in adulthood suggest that adolescence is an opportune time to evaluate links between sleep duration and cardiovascular disease risk. We examined associations among actigraphy-assessed sleep duration and sleep debt with elevated C-reactive protein (CRP), a known risk factor for cardiovascular disease. METHODS: Participants were 244 (56% Black, 48% male) healthy high school students, each of whom wore wrist actigraphs for one week and provided a fasting blood draw. CRP was examined as both a continuous and categorical outcome, with CRP >3 mg/L identifying a High Risk Group. RESULTS: Sleep duration and sleep debt were significantly associated with CRP High Risk Group in covariate-adjusted analyses. Shorter sleep duration on school nights was associated with a greater likelihood of being in the High Risk CRP Group. Likelihood of being in the High Risk CRP Group was doubled in students who obtained an average of two or more hours of "catch up" sleep on weekend nights. CONCLUSIONS: Reduced weekday sleep duration and sleep debt were both associated with CRP Risk Group in adolescence. That these relationships may be observed prior to the onset of clinical disease suggests that adolescence may provide an opportune period for disease prevention.

Single-parent family structure and sleep problems in black and white adolescents.

OBJECTIVES: Sleep is critical for adolescent health and is influenced by the family environment. In our study, we examined if family structure defined as single- vs. two-parent households affected adolescent sleep. METHODS: Participants were 242 (57% black; 47% boys) healthy adolescents (mean age, 15.7 years). Sleep was measured using self-report and wrist actigraphy over seven consecutive nights. Outcomes were actigraphy-assessed sleep duration and sleep efficiency (SE) for the full week and weekends and weekdays separately, as well as self-reported sleep-wake problems and variability in bedtimes. Linear regression examined the relationship between family structure and sleep, after adjusting for age, sex, race, body mass index, and depressive symptoms, parental education, family conflict, and financial strain. Race and sex were examined as potential moderators. RESULTS: After adjusting for covariates, adolescents from single-parent households had poorer SE across the week and shorter sleep duration on weekends. White adolescents from two-parent households had fewer sleep-wake problems and lower bedtime variability, whereas black adolescents from single-parent households had the lowest weekend SE. There were no significant differences in family structure-sex interactions. CONCLUSION: Our findings are the first to demonstrate that single-parent family structure is an independent correlate of sleep problems in adolescents and they highlight the moderating role of race.

Do reports of sleep disturbance relate to coronary and aortic calcification in healthy middle-aged women?: Study of women's health across the nation.

BACKGROUND: Poor sleep may be associated with the cardiovascular disease (CVD) morbidity and mortality. It is less clear if poor sleep is associated with subclinical CVD. We evaluated cross-sectional associations between self-reported sleep disturbance and duration and calcification in the coronary arteries (CAC) and aorta (AC) in healthy mid-life women. METHODS: 512 black and white women enrolled in the SWAN Heart Study, underwent a computed tomography protocol for measurement of CAC and AC and completed questionnaires about their sleep. Linear and partial proportional logit regression analyses adjusted for site, race, age, body mass index, and the Framingham risk score (model 1). Additional covariates of education, perceived health, hypnotic medication and alcohol use were evaluated (model 2), plus depressive symptoms (model 3). RESULTS: AC was related to higher levels of trouble falling asleep, waking earlier than planned, overall poor sleep quality, and cough/snoring and shorter sleep duration in linear regression analyses (model 1). Adjustments for additional covariates showed that poor sleep quality and waking earlier than planned remained associated with higher AC (models 2 and 3). CAC was unrelated to sleep characteristics. CONCLUSIONS: Poor sleep quality is related to AC in middle-aged women. Sleep quality should routinely be assessed in mid-life women.

Sleep duration and insulin resistance in healthy black and white adolescents.

STUDY OBJECTIVES: Poor sleep may play a role in insulin resistance and diabetes risk. Yet few studies of sleep and insulin resistance have focused on the important developmental period of adolescence. To address this gap, we examined the association of sleep and insulin resistance in healthy adolescents. DESIGN: Cross-sectional. SETTING: Community setting in one high school. PARTICIPANTS: 245 (137 African Americans, 116 males) high school students. MEASUREMENTS AND RESULTS: Participants provided a fasting blood draw and kept a sleep log and wore a wrist actigraph for one week during the school year. Participants' families were from low to middle class based on family Hollingshead scores. Total sleep time across the week averaged 7.4 h by diary and 6.4 h by actigraph; homeostatic model assessment of insulin resistance ([HOMA-IR] unadjusted) averaged 4.13. Linear regression analyses adjusted for age, race, gender, body mass index, and waist circumference showed that the shorter the sleep, the higher the HOMA-IR, primarily due to sleep duration during the week. No evidence was found for long sleep being associated with elevated HOMA-IR. Fragmented sleep was not associated with HOMA-IR but was associated with glucose levels. CONCLUSIONS: Reduced sleep duration is associated with HOMA-IR in adolescence. Long sleep duration is not associated. Interventions to extend sleep duration may reduce diabetes risk in youth.

Napping, nighttime sleep, and cardiovascular risk factors in mid-life adults.

STUDY OBJECTIVES: To evaluate the relations between sleep characteristics and cardiovascular risk factors and napping behavior, and to assess whether daytime napping leads to subsequent better or worse sleep. METHODS: The sample consisted of 224 (African American, Caucasian, and Asian) middle-aged men and women. Sleep measures included nine nights of actigraphy and sleep diaries, sleep questionnaires, and one night of polysomnography to measure sleep disordered breathing. RESULTS: More frequent napping was associated with shorter nighttime sleep duration averaged across the nine nights of actigraphy (especially among African Americans), more daytime sleepiness, more pain and fatigue by diary, and increased body mass index and waist circumference. Shorter nighttime sleep duration was associated with taking a nap during the next day and taking a nap was associated with less efficient sleep the next night. CONCLUSIONS: Napping in middle-aged men and women is associated with overall less nighttime sleep in African Americans and lower sleep efficiency as measured by actigraphy, and increased BMI and central adiposity. These findings point to the importance of measuring of napping in understanding associations of sleep with cardiovascular risk.