Association between sleep and blood pressure in midlife: the CARDIA sleep study

Self-Reported Experiences of Discrimination and Cardiovascular Disease

Researchers have long speculated that exposure to discrimination may increase cardiovascular disease (CVD) risk but compared to other psychosocial risk factors, large-scale epidemiologic and community based studies examining associations between reports of discrimination and CVD risk have only emerged fairly recently. This review summarizes findings from studies of self-reported experiences of discrimination and CVD risk published between 2011-2013. We document the innovative advances in recent work, the notable heterogeneity in these studies, and the considerable need for additional work with objective clinical endpoints other than blood pressure. Implications for the study of racial disparities in CVD and clinical practice are also discussed.

Predictors of poor sleep quality among Lebanese university students: association between evening typology, lifestyle behaviors, and sleep habits

Adequate, good night sleep is fundamental to well-being and is known to be influenced by myriad biological and environmental factors. Given the unavailability of sleep data about Lebanon, the cultural shifts and socioeconomic pressures that have affected many aspects of society, particularly for students and working adults, as well as our understanding of sleep in university students in other countries, we conducted a national study to assess sleep quality and factors contributing to sleep and general health in a culture-specific context. A self-filled questionnaire, inquiring about sociodemographics, health-risk behaviors, personal health, and evaluating sleep quality and chronotype using standard scales was completed by 540 students at private and public universities in Lebanon. Overall, they reported sleeping 7.95±1.34 hours per night, although 12.3% reported sleeping <6.5 hours and more than half scored in the poor-sleeper category on the Pittsburgh Sleep Quality Index (PSQI). Sleep timing differed markedly between weekdays and weekends, with bedtimes and wake-up times delayed by 1.51 and 2.43 hours, respectively, on weekends. While most scored in the "neither type" category on the Morningness-Eveningness Questionnaire (MEQ), 24.5% were evening types and 7.3% were morning types. MEQ score was significantly correlated with smoking behavior and daily study onset, as well as with PSQI score, with eveningness associated with greater number of cigarettes, later study times, and poor sleep. We conclude that the prevalence of poor sleep quality among Lebanese university students is associated with reduced sleep duration and shifts in sleep timing between weekdays and weekends, especially among evening types. While chronotype and certain behavioral choices interact to affect sleep dimensions and quality, raising awareness about the importance of obtaining adequate nighttime sleep on daily performance and avoiding risky behaviors may help Lebanese students make better choices in school and work schedules.

Habitual sleep duration associated with self-reported and objectively determined cardiometabolic risk factors

BACKGROUND

Self-reported short or long sleep duration has been associated with adverse cardiometabolic health outcomes in laboratory and epidemiologic studies, but interpretation of such data has been limited by methodologic issues.

METHODS

Adult respondents of the 2007-2008 US National Health and Nutrition Examination Survey (NHANES) were examined in a cross-sectional analysis (N=5649). Self-reported sleep duration was categorized as very short (<5 h), short (5-6 h), normal (7-8 h), or long (≥9 h). Obesity, diabetes mellitus (DM), hypertension, and hyperlipidemia were objectively assessed by self-reported history. Statistical analyses included univariate comparisons across sleep duration categories for all variables. Binary logistic regression analyses and cardiometabolic factor as outcome, with sleep duration category as predictor, were assessed with and without covariates. Observed relationships were further assessed for dependence on race/ethnicity.

RESULTS

In adjusted analyses, very short sleep was associated with self-reported hypertension (odds ratio [OR], 2.02, [95% confidence interval {CI},1.45-2.81]; P<0.0001), self-reported hyperlipidemia (OR, 1.96 [95% CI, 1.43-2.69]; P<0.0001), objective hyperlipidemia (OR, 1.41 [95% CI, 1.04-1.91]; P=0.03), self-reported DM (OR, 1.76 [95% CI, 1.13-2.74]; P=0.01), and objective obesity (OR, 1.53 [95% CI, 1.03-1.43]; P=0.005). Regarding short sleep (5-6 h), in adjusted analyses, elevated risk was seen for self-reported hypertension (OR, 1.22 [95% CI, 1.02-1.45]; P=0.03) self-reported obesity (OR, 1.21 [95% CI, 1.03-1.43]; P=0.02), and objective obesity (OR, 1.17 [95% CI, 1.00-1.38]; P<0.05). Regarding long sleep (≥9 h), no elevated risk was found for any outcomes. Interactions with race/ethnicity were significant for all outcomes; race/ethnicity differences in patterns of risk varied by outcome studied. In particular, the relationship between very short sleep and obesity was strongest among blacks and the relationship between short sleep and hypertension is strongest among non-Hispanic whites, blacks, and non-Mexican Hispanics/Latinos.

CONCLUSIONS

Short sleep duration is associated with self-reported and objectively determined adverse cardiometabolic outcomes, even after adjustment for many covariates. Also, these patterns of risk depend on race/ethnicity.

Correlation between blood pressure changes and AMS, sleeping quality and exercise upon high-altitude exposure in young Chinese men

BACKGROUND

Excessive elevation of arterial blood pressure (BP) at high altitude can be detrimental to our health due to acute mountain sickness (AMS) or some AMS symptoms. This prospective and observational study aimed to elucidate blood pressure changes induced by exposure to high-altitude hypoxia and the relationships of these changes with AMS prevalence, AMS severity, sleep quality and exercise condition in healthy young men.

METHODS

A prospective observational study was performed in 931 male young adults exposed to high altitude at 3,700 m (Lhasa) from low altitude (LA, 500 m). Blood pressure measurement and AMS symptom questionnaires were performed at LA and on day 1, 3, 5, and 7 of exposure to high altitude. Lake Louise criteria were used to diagnose AMS. Likewise, the Athens Insomnia Scale (AIS) and the Epworth Sleepiness Scale (ESS) were filled out at LA and on day 1, 3, and 7 of exposure to high altitude.

RESULTS

After acute exposure to 3,700 m, diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) rose gradually and continually (P < 0.05). Analysis showed a relationship with AMS for only MABP (P < 0.05) but not for SBP and DBP (P > 0.05). Poor sleeping quality was generally associated with higher SBP or DBP at high altitude, although inconsistent results were obtained at different time (P < 0.05). SBP and Pulse BP increased noticeably after high-altitude exercise (P < 0.05).

CONCLUSIONS

Our data demonstrate notable blood pressure changes under exposure to different high-altitude conditions: 1) BP increased over time. 2) Higher BP generally accompanied poor sleeping quality and higher incidence of AMS. 3) SBP and Pulse BP were higher after high-altitude exercise. Therefore, we should put more effort into monitoring BP after exposure to high altitude in order to guard against excessive increases in BP.

Sleep and pregnancy-induced hypertension: a possible target for intervention?

Sleep disturbances in the general population are associated with elevated blood pressure. This may be due to several mechanisms, including sympathetic activation and hypothalamic-pituitary-adrenal (HPA) axis disturbance. Elevated blood pressure in pregnancy can have devastating effects on both maternal and fetal health and is associated with increased risk for preeclampsia and poor delivery outcomes. Preliminary evidence suggests that mechanisms linking sleep and blood pressure in the general population may also hold in the pregnant population. However, the effects of disturbed sleep on physiologic mechanisms that may directly influence blood pressure in pregnancy have not been well studied. The role that sleep disturbance plays in gestational blood pressure elevation and its subsequent consequences warrant further investigation. This review evaluates the current literature on sleep disturbance and elevated blood pressure in pregnancy and proposes possible treatment interventions.

Short sleep duration as a risk factor for the development of the metabolic syndrome in adults

OBJECTIVE

The objective of this study was to investigate the association between self-reported sleep duration and the incidence of features of the metabolic syndrome in adults.

METHODS

A longitudinal analysis from the Quebec Family Study (Canada) was conducted on 293 participants, aged 18 to 65 years, followed for a mean of 6 years (until 2001). Participants were categorized as short (≤6 h), adequate (7-8 h) or long (≥9 h) sleepers. The metabolic syndrome was defined according to the American Heart Association/National Heart, Lung, and Blood Institute's criteria. The hypertriglyceridemic waist phenotype was defined as high waist circumference (≥90 cm in men and ≥85 cm in women) combined with high fasting triglyceride level (≥2.0 mmol/L in men and ≥1.5 mmol/L in women).

RESULTS

The incidence rates of metabolic syndrome and hypertriglyceridemic waist phenotype were 9.9% and 7.5%, respectively. Short sleepers were significantly more at risk of developing the metabolic syndrome (relative risk (RR): 1.74; 95% confidence interval (CI): 1.05-2.72) and the hypertriglyceridemic waist phenotype (RR: 1.82; 95% CI: 1.16-2.79), compared to those sleeping 7 to 8h per night after adjusting for covariates. However, long sleep duration was not associated with an increased risk of developing the metabolic syndrome or the hypertriglyceridemic waist phenotype (either unadjusted or adjusted models).

CONCLUSION

Short sleep duration is associated with an increased risk of developing features of the metabolic syndrome in adults.

Sleep and risk for high blood pressure and hypertension in midlife women: the SWAN (Study of Women's Health Across the Nation) Sleep Study

OBJECTIVE

Inadequate self-reported sleep is related to high blood pressure (BP). Our study investigated cross-sectional and longitudinal relationships between poor sleep measured by in-home polysomnography (PSG) and BP.

METHODS

Midlife participants (132 black, 164 white, and 59 Chinese) were from the SWAN (Study of Women's Health Across the Nation) ancillary sleep study. In-home PSG measured sleep apnea, duration, efficiency, and electroencephalogram (EEG) total delta and beta power during nonrapid eye movement (NREM) sleep. Women subsequently were followed annually for 4.5 (1-7)years for BP and hypertensive status (>140/90 mmHg or use of antihypertensive medication). Covariates were age, race, site, and educational attainment, with time-covariates of BP medications, body mass index, diabetes mellitus (DM), cigarette smoking, and menopausal status.

RESULTS

Sleep duration and efficiency were unrelated to BP cross-sectionally or longitudinally in multivariate models. Women with higher total beta power were more likely to be hypertensive at the time of the sleep study; women with lower total delta power were more likely to show increases in diastolic BP (DBP) and to be at risk for incident hypertension across follow-up.

CONCLUSIONS

Low NREM delta power may be a risk factor for future hypertension. Quantitative EEG measures are worthy of future investigations of hypertension risk.

Longitudinal associations between objective sleep and lipids: the CARDIA study

STUDY OBJECTIVE

To investigate the longitudinal relationships between actigraph-derived sleep duration, fragmentation, and lipid levels.

DESIGN AND SETTING

Longitudinal data from the Coronary Artery Risk Development in Young Adults Sleep Study (2003-05), an observational cohort at the Chicago site.

PARTICIPANTS

There were 503 black and white adults, ages 32-51 years, with no prior history of cardiovascular disease.

INTERVENTIONS

N/A.

MEASUREMENT AND RESULTS

Sleep duration and fragmentation were measured using 6 days of wrist actigraphy. Sleep quality was measured with the Pittsburgh Sleep Quality Index. The outcome variables, measured at 3 examinations over 10 years (Baseline [2000-01], 5-year [2005-06], and 10-year follow-up [2010-11]), were total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG), and TC/HDL ratio. The associations between each sleep parameter and 10-year change in lipids were analyzed with generalized estimating equation models adjusting for relevant confounders. After adjustment, each hour increase in sleep duration was significantly associated with higher TC (5.2 mg/dL, 95%CI: 1.7, 8.6) and LDL (3.4 mg/dL, 95%CI: 0.2, 6.6) in the total sample, a 1.1 mg/dL increase in TG (95%CI: 1.0, 1.1) among men, and a borderline significant greater odds for a TC/HDL ratio ≥ 5 among men (OR: 1.37, 95%CI: 0.99, 1.90). Overall, sleep fragmentation and sleep quality scores were not associated with change in lipids.

CONCLUSIONS

Beyond relevant covariates, over a 10-year follow-up, longer objective sleep duration was longitudinally and significantly associated with a poorer lipid profile. Greater objective sleep fragmentation and self-reported poor sleep quality were not related to a poorer lipid profile.

The effects of poor sleep on cognitive, affective, and physiological responses to a laboratory stressor

BACKGROUND

Recent research suggests that poor sleep may be associated with altered stress regulation.

PURPOSE

This study aims to examine the associations between prior-night and prior-month sleep measures and affective, cognitive, and physiological responses to a laboratory stressor.

METHODS

Ninety-eight (50 % female) young adults completed measures of sleep quality in the context of a laboratory stress study. Measures included positive (PA) and negative affects (NA) and blood pressure (BP) reactivity, as well as change in pre-sleep arousal.

RESULTS

Prior-month poor sleep quality and sleep disturbances predicted dampened BP reactivity. Both prior-night and prior-month sleep quality predicted greater decrease in PA. Sleep-associated monitoring predicted NA reactivity and prolonged cognitive and affective activation. Prior-month sleep continuity predicted greater cognitive pre-sleep arousal change, and prior-month sleep quality, daytime dysfunction, and disturbances predicted prolonged cognitive and affective activation.

CONCLUSION

Findings suggest that inadequate sleep confers vulnerability to poor cognitive, affective, and physiological responses to stress.

Short sleep duration measured by wrist actimetry is associated with deteriorated glycemic control in type 1 diabetes

OBJECTIVE

Sleep restriction has been associated with deteriorated insulin sensitivity. The effects of short sleep duration have been explored little in patients with type 1 diabetes. This study addresses the question of whether sleep curtailment affects HbA1c levels in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Seventy-nine adult patients with type 1 diabetes (median age 40 years [IQR 23-49]; 47% men) were recruited to wear a wrist actimetry sensor during 3 consecutive days to assess mean sleep duration during normal daily life. A subsample of 37 patients also performed 24-h ambulatory blood pressure monitoring (ABPM). Medical history, sleep questionnaires, and diabetes-related quality of life (DQOL) were assessed.

RESULTS

Patients having shorter sleep duration--less than 6.5 h (n=21)--had higher levels of HbA1c (P=0.01) than patients with longer sleep duration, above 6.5 h (n=58). In a multivariable regression model including shorter versus longer sleep duration, diabetes duration, DQOL score, and daily activity, sleep duration was the only variable independently associated with HbA1c (R2=10%). In patients who performed 24-h ABPM, patients with a nondipping pattern of blood pressure exhibited shorter sleep duration than patients with a dipping pattern of blood pressure.

CONCLUSIONS

Shorter sleep duration is associated with higher HbA1c levels in patients with type 1 diabetes, as well as with a nondipping pattern of blood pressure, anticipating a long-term deleterious impact on the risk of microvascular complications. Further studies should test whether extending the duration of sleep may improve both HbA1c and blood pressure in type 1 diabetes.

Sleep duration and cardiovascular responses to stress in undergraduate men

Short sleep has been related to incident cardiovascular disease, but physiological mechanisms accounting for this relationship are largely unknown. This study examines sleep duration and cardiovascular stress responses in 79 healthy, young men. Sleep duration was assessed by wrist actigraphy for seven nights. Participants then completed a series of laboratory stress tasks while heart rate and blood pressure were monitored. Shorter total sleep time was related to a greater reduction in high-frequency heart rate variability during stress tasks, and to prolonged elevations in heart rate and diastolic pressure following tasks. Associations were independent of age, race, body mass index, caffeine intake, and smoking status. In sum, healthy young men with shorter actigraphy-assessed sleep exhibit less cardiac vagal activity, and poorer heart rate and diastolic blood pressure recovery, upon encountering stressful stimuli, than those with longer sleep.

Seven to eight hours of sleep a night is associated with a lower prevalence of the metabolic syndrome and reduced overall cardiometabolic risk in adults

Background

Previous studies looking at the relationship between sleep duration and the metabolic syndrome have only used a dichotomous approach (presence/absence) and failed to adjust for important confounding factors. The objective of the present study was to examine the association between self-reported sleep duration and features of the metabolic syndrome in adults.

Methods

A cross-sectional analysis from the Quebec Family Study (Canada) was conducted on 810 participants aged 18 to 65 years. Participants were categorized as short (≤6 h), adequate (7–8 h) or long (≥9 h) sleepers. The metabolic syndrome was defined according to the American Heart Association/National Heart, Lung, and Blood Institute’s criteria.

Results

Overall, 24.6% of the sample had the metabolic syndrome. A U-shaped relationship between sleep duration and the prevalence of metabolic syndrome (33.3%, 22.0% and 28.8% in short, adequate and long sleepers, respectively) was observed (P<0.01). Only short sleepers had a significant increase in the odds of having the metabolic syndrome (OR = 1.76, 95% CI = 1.08–2.84) compared to adequate sleepers after adjustment for age, sex, smoking habits, highest education level, total annual family income, alcohol consumption, coffee intake, menopausal status, daily caloric intake, and moderate-to-vigorous physical activity. Likewise, the clustered cardiometabolic risk score (i.e. continuous risk score based on the metabolic syndrome components) was significantly higher in short sleepers compared to adequate sleepers after adjustment for covariates (P<0.05).

Conclusion

Sleeping ≤6 h per night is associated with an elevated cardiometabolic risk score and an increase in the odds of having the metabolic syndrome after adjusting for possible confounders. These results strongly suggest that short sleep duration is a risk factor for the metabolic syndrome.

The relationship of sleep duration and insomnia to risk of hypertension incidence: a meta-analysis of prospective cohort studies

To assess whether habitual sleep duration or insomnia increase the incidence of hypertension. PubMed, EMBASE and Cochrane were searched without language restriction. Prospective cohort studies of adults with at least a 1-year follow-up duration were included. Habitual sleep duration or symptoms of insomnia were assessed as baseline exposure, and the outcome was incidence of hypertension. Subgroup, meta-regression and sensitivity analyses were conducted to assess heterogeneity, and Egger's test was used to assess publication bias. Eleven studies (17 cohorts) were included. Short sleep duration, sleep continuity disturbance (SCD), early-morning awakening (EMA) and combined symptoms of insomnia increased the risk of hypertension incidence (the relative risks (95% confidence intervals) were 1.21 (1.05–1.40) for short sleep duration, 1.20 (1.06–1.36) for SCD, 1.14 (1.07–1.20) for EMA and 1.05 (1.01–1.08) for combined insomnia symptoms). Less evidence exists to support conclusions about the association between long sleep duration or difficulty falling asleep (DFA) and hypertension incidence. No obvious heterogeneity or publication biases were found. Our meta-analysis demonstrates that short sleep duration and single/combined symptoms of insomnia (except DFA) are associated with an increased risk of hypertension incidence. It is important to consider sleep duration and insomnia during hypertension prevention and treatment. More laboratory studies on potential mechanisms and prospective observational studies with objective measures of sleep are needed.

In search of objective components for sleep quality indexing in normal sleep

The main goal of this study was to investigate to what extent polysomnographic (PSG) recordings of nocturnal human sleep can provide information about sleep quality in terms of correlation with a set of daytime measures. These measures were designed with the aim of comprising selected quality of night sleep and consist of subjective sleep quality ratings, neuropsychological tests and physiological parameters. First, a factor analysis model was applied to the large number of daytime measures of sleep quality in order to detect their latent structure. Secondly, in addition to the gold standard sleep staging method to arrive at variables about sleep architecture from PSG, we applied a recently developed continuous sleep representation by considering the probabilistic sleep model (PSM) describing the microstructure of sleep. Significant correlations between sleep architecture and daytime variables of sleep quality were found. Both the factor analysis and the PSM helped maximize the information about this relationship.

Sleep architecture variation: a mediator of metabolic disturbance in individuals with major depressive disorder

Remarkable proportions of individuals diagnosed with major depressive disorder (MDD) have comorbid metabolic disturbances (i.e., obesity, type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia), and vice versa. Accumulating evidence suggests that common pathophysiologic pathways such as a chronic, low-grade, proinflammatory state mediate this frequent co-occurrence. However, it remains unclear what traits precede the onset and increase the risk for these pathologic states. The aim of our review was to evaluate the evidentiary base supporting the hypothesis that the increased hazard for metabolic disturbance in MDD subpopulations (and vice versa) is mediated in part by endophenotypic variations in sleep architecture. We conducted a PubMed search of all English-language literature with the following search terms: sleep disturbance, circadian rhythm, inflammation, metabolic syndrome, obesity, MDD, mood disorder, prodrome, T2DM, cytokine, interleukin, hypertension, dyslipidemia, and hypercholesterolemia. Longitudinal and meta-analysis data indicate that specific variations in sleep architecture (i.e., decreased slow-wave sleep [SWS], increased rapid eye movement [REM] density) precede the onset of depressive symptomatology for a subpopulation of individuals. The same sleep architecture variations also are associated with obesity, T2DM, and hypertension. Decreased SWS and increased REM density is correlated with an increase in proinflammatory cytokines (e.g., IL-6, tumor necrosis factor, etc.). This proinflammatory state has been independently shown to be associated with MDD and metabolic disturbances. Taken together, our review suggests that sleep architecture variation of increased REM density and decreased SWS may be an endophenotypic trait, which serves to identify a subpopulation at increased risk for depressive symptoms and metabolic disturbances. Future research is needed to discern the predictive value, sensitivity, and specificity of using sleep architecture variation as a biomarker for MDD and metabolic disturbances. Validation of this marker would have broad clinical implications, such as primary, secondary, and tertiary preventative health strategies.

Sleep-wake activity rhythm and health-related quality of life among patients with coronary artery disease and in a population-based sample--an actigraphy and questionnaire study

The aim of this study was to explore whether there are gender differences in sleep and health-related quality of life in patients with coronary artery disease (CAD) and a matched population-based sample and to see how subjectively rated sleep is associated with actigraphy. Secondly, to explore whether factors that predict patients' sleep quality could be identified. Fifty-seven patients with stable CAD and 47 participants from a population-based sample were included. All participants completed the Uppsala Sleep Inventory (USI), the Epworth Sleepiness Scale and the SF-36. Actigraphy recordings and a sleep diary were performed for seven 24-h periods. Multiple stepwise regression analysis showed that sleep duration, sleep onset latency, nocturnal awakenings, vitality (SF-36) and body mass index explained 60% of the sleep quality outcome (USI). Sleep duration, sleep efficiency and fragmentation index assessed with actigraphy and sleep diary accounted for 36% of the sleep quality outcome (diary). The result can form the basis for a non-pharmacological, self-care programme supported and led by nurses.

Insomnia with objective short sleep duration: the most biologically severe phenotype of the disorder

Until recently, the association of chronic insomnia with significant medical morbidity was not established and its diagnosis was based solely on subjective complaints. We present evidence that insomnia with objective short sleep duration is the most biologically severe phenotype of the disorder, as it is associated with cognitive-emotional and cortical arousal, activation of both limbs of the stress system, and a higher risk for hypertension, impaired heart rate variability, diabetes, neurocognitive impairment, and mortality. Also, it appears that objective short sleep duration is a biological marker of genetic predisposition to chronic insomnia. In contrast, insomnia with objective normal sleep duration is associated with cognitive-emotional and cortical arousal and sleep misperception but not with signs of activation of both limbs of the stress system or medical complications. Furthermore, the first phenotype is associated with unremitting course, whereas the latter is more likely to remit. We propose that short sleep duration in insomnia is a reliable marker of the biological severity and medical impact of the disorder. Objective measures of sleep obtained in the home environment of the patient would become part of the routine assessment of insomnia patients in a clinician's office setting. We speculate that insomnia with objective short sleep duration has primarily biological roots and may respond better to biological treatments, whereas insomnia with objective normal sleep duration has primarily psychological roots and may respond better to psychological interventions alone.

Sleep in America: role of racial/ethnic differences

Sleep duration in America has gradually declined over the last four decades and appears to have reached a plateau for the last six years, with recent studies reporting that the population's current average sleep duration is approximately 6 h. In this paper, we examine epidemiologic and community-based data on sleep complaints reported by American adults, specifically addressing the role of race/ethnicity in the subjective report of sleep problems. Subjective and objective findings indicate that black (throughout the text, we use the term black in lieu of African American for there are instances where we refer to individuals with self-ascribed race/ethnicity as black, African American, African, or Caribbean American; the term white is used to denote individuals of European descent). Americans have higher rates of long (≥9 h) and short (≤5 h) sleep than their white counterparts, and this may mediate a higher risk of cardiovascular disease, obesity and diabetes among blacks. In addition, studies show mixed results on sleep complaints among blacks compared to those among other ethnicities. This paper explores factors that may contribute to racial/ethnic differences in sleep including intra-ethnic variation, cultural biases, genetics and psychosocial factors.

Association between short total sleep time and hypertension: the Skara Sleep Cohort

OBJECTIVES

Apnea hypopnea index (AHI) is used to study the association between obstructive sleep apnea (OSA) and hypertension, but the independent contributions of total sleep time (TST) and apnea/hypopnea event count to hypertension have not been previously investigated. We studied the relationship between polysomnographically assessed TST and hypertension in a sex-balanced community-dwelling cohort of hypertensive patients and normotensive controls (Skara Sleep Cohort).

METHODS

Participants (n = 344, men 173, age 61.2 ± 6.5 years, BMI 28.6 ± 4.8 kg/m, mean ± SD) underwent ambulatory home polysomnography. Hypertension was defined according to contemporary Swedish national guidelines. A multivariate logistic regression model was used to predict hypertension status from TST and apnea/hypopnea count (total events/night) adjusting for sex, age and BMI.

RESULTS

OSA was highly prevalent in this population (AHI 26 ± 4 events/h). Hypertensive patients had shorter TST than normotensive patients (353 ± 81 vs. 389 ± 65 min, P < 0.001), whereas total apnea/hypopnea count did not differ (167 ± 138 vs. 146 ± 148 events/night, P = 0.2). Multivariate logistic regression analysis revealed that short TST was associated with hypertension status [odds ratio 2.0; 95% confidence interval (95% CI) 1.2-3.3; P = 0.0015]. The significant association between apnea/hypopnea count and hypertension status was nonlinear (odds ratio 2.6; 95% CI 1.2-5.8; P = 0.04). The type of antihypertensive treatment was not found to significantly influence TST.

CONCLUSION

Short sleep time assessed by polysomnography was associated with hypertension in this community-dwelling population. Short sleep and presence of sleep apnea appear to independently link to hypertension.

Chronic exposure to everyday discrimination and sleep in a multiethnic sample of middle-aged women

OBJECTIVE

Researchers have suggested that poor sleep may play a role in the association between discrimination and health, but studies linking experiences of discrimination to sleep are limited. The authors examined associations between reports of everyday discrimination over 4 years (chronic everyday discrimination) and subjective and objective indicators of poor sleep.

METHOD

Participants were 368 African American, Caucasian, and Chinese women from the Study of Women's Health Across the Nation Sleep Study. Everyday discrimination was assessed each year from baseline through the third follow-up exam via questionnaire with the Everyday Discrimination Scale (intraclass correlation coefficient over 4 years = .90). Subjective sleep complaints were measured beginning in Year 5 with the Pittsburgh Sleep Quality Index. Objective indices of sleep continuity, duration, and architecture were assessed via in-home polysomnography, beginning in Year 5.

RESULTS

In linear regression analyses adjusted for age, race/ethnicity, and financial strain, chronic everyday discrimination was associated with more subjective sleep complaints (Estimate = 1.52, p < .001) and polysomnography-assessed wakefulness after sleep onset (Estimate = .19, p < .02), a marker of sleep continuity. Findings did not differ by race/ethnicity and remained significant after adjusting for menopausal status, body mass index, medication use, and depressive symptoms.

CONCLUSION

Experiences of chronic everyday discrimination are independently associated with both subjective and objective indices of poor sleep. Findings add to the growing literature linking discrimination to key markers of biobehavioral health.

Sleep duration and risk for hypertension in women: results from the nurses' health study

BACKGROUND

Acute sleep restriction has been shown to increase blood pressure and sympathetic nervous system activity.

METHODS

We investigated the relationships between sleep duration and hypertension among women whose sleep durations were self-reported in 1986 (n = 82,130) and 2000 (n = 71,658) in the Nurses' Health Study I (NHS-I) and in 2001 (n = 84,674) in the Nurses' Health Study II (NHS-II).

RESULTS

After controlling for multiple risk factors in logistic regression models, the prevalence of hypertension was significantly higher among women in all 3 groups who slept ≤5 hours (odds ratio = 1.19, 95% confidence interval [CI] = 1.14-1.25) per night compared with 7 hours. In prospective analyses using Cox regression shorter sleep duration of ≤5 hours per night was significantly associated with a higher incidence of hypertension only in younger women (hazard ratio [HR] =1.20, 95% CI = 1.09-1.31 for those aged <50 years; HR = 1.11, 95% CI = 1.00-1.23 for those aged 50-59 years). In both prevalent and incident analyses, results were consistent with obesity acting as a partial mediator. Results were not consistent with diabetes or hypercholesterolemia acting as mediators or with shift work, snoring, menopause, or postmenopausal hormone therapy acting as effect modifiers.

CONCLUSIONS

Sufficient sleep could represent a lifestyle practice worthy of investigation as an approach to reduce hypertension incidence and prevalence.

Total sleep time and other sleep characteristics measured by actigraphy do not predict incident hypertension in a cohort of community-dwelling older men

STUDY OBJECTIVE

To evaluate whether actigraphy-measured total sleep time and other sleep characteristics predict incident hypertension in older men.

METHODS

Study subjects were community-dwelling participants in the ancillary sleep study of the Osteoporotic Fractures in Men Study (MrOS) who were normotensive at the time of actigraphy (based on self-report, lack of antihypertensive medication use, and with systolic blood pressure < 140 mm Hg and diastolic blood pressure < 90 mm Hg). In 853 community-dwelling men 67 years and older (mean 75.1 years), sleep measures (total sleep time [TST]), percent sleep [%-sleep], latency, and wake after sleep onset [WASO]) were obtained using validated wrist actigraphy with data collected over a mean duration of 5.2 consecutive 24-h periods. We evaluated incident hypertension (based on self-report, use of antihypertensive medication, or measured systolic blood pressure ≥ 140 mm Hg or diastolic blood pressure ≥ 90 mm Hg) at a follow-up visit an average of 3.4 years later. Baseline prehypertension was defined as a systolic blood pressure 120 to < 140 mm Hg or diastolic blood pressure 80 to < 90 mm Hg.

RESULTS

At follow-up, 31% of initially normotensive men were hypertensive (264 of 853). Those with incident hypertension had higher baseline body mass index (BMI; kg/m(2)) and were more likely to have had prehypertension at the sleep visit than those men who remained normotensive. However, neither TST (reference 6 to < 8 h; < 6 h OR 0.96 [95% CI 0.7, 1.3] and ≥ 8 h OR 0.93 [0.5, 1.7]) nor the other actigraphic-measured sleep variables, including % -sleep (reference > 85%; < 70% OR 1.17 [0.66, 2.08]) and 70% to ≤ 85% OR 1.23 (0.9, 1.68), sleep latency (reference < 30 min; ≥ 30 min OR 1.29 [0.94, 1.76]), or WASO (reference < 30 min; 30 to < 60 min OR 0.7 [0.43, 1.14] and ≥ 60 min OR 0.92 [0.58, 1.47]) differed in those community-dwelling men who developed incident hypertension compared to those who remained normotensive.

CONCLUSION

TST and other sleep parameters determined by wrist actigraphy were not associated with incident hypertension in community-dwelling older men.

Linking sleep to hypertension: greater risk for blacks

Background. Evidence suggests that insufficient sleep duration is associated with an increased likelihood for hypertension. Both short (<6 hours) and long (>8 hour) sleep durations as well as hypertension are more prevalent among blacks than among whites. This study examined associations between sleep duration and hypertension, considering differential effects of race and ethnicity among black and white Americans. Methods. Data came from a cross-sectional household interview with 25,352 Americans (age range: 18-85 years). Results. Both white and black short sleepers had a greater likelihood of reporting hypertension than those who reported sleeping 6 to 8 hours. Unadjusted logistic regression analysis exploring the race/ethnicity interactions between insufficient sleep and hypertension indicated that black short (<6 hours) and long (>8 hours) sleepers were more likely to report hypertension than their white counterparts (OR = 1.34 and 1.37, resp.; P < 0.01). Significant interactions of insufficient sleep with race/ethnicity were observed even after adjusting to effects of age, sex, income, education, body mass index, alcohol use, smoking, emotional distress, diabetes, coronary heart disease, and stroke. Conclusion. Results suggest that the race/ethnicity interaction is a significant mediator in the relationship between insufficient sleep and likelihood of having a diagnosis of hypertension.

Epidemiological evidence for the link between sleep duration and high blood pressure: a systematic review and meta-analysis

OBJECTIVES

We aim to assess if the relationship between short or long sleep duration and hypertension is present among adults from epidemiological evidence and to investigate the relationship quantitatively.

METHODS

We performed a comprehensive search of cross-sectional and longitudinal studies using PubMed and the Cochrane Library through February 2012. Our search was supplemented by reviewing reference lists of original and relevant reviews. After the related data were extracted by two investigators independently, pooled odds ratios (ORs) or relative risks (RRs) were estimated using a random-effects model or a fixed-effects model. Publication bias was evaluated, while sensitivity and meta-regression analyses were performed.

RESULTS

Twenty-four adult studies met our inclusion criteria, with ages ranging from 18 to 106 years. Twenty-one studies involving 225,858 subjects were included in the meta-analysis. The pooled results from the cross-sectional studies showed that short sleep duration was associated with a greater risk for hypertension (OR, 1.21; 95% confidence interval [CI], 1.09-1.34; P<0.001), and long sleep duration also increased the risk for hypertension (OR, 1.11; 95% CI, 1.04-1.18; P=0.003). There was no evidence of publication bias. Pooled analysis from the longitudinal studies indicated a significant association between short sleep duration and hypertension (RR, 1.23; 95% CI, 1.06-1.42; P=0.005), but an insignificant relationship between long sleep duration and hypertension (RR, 1.02; 95% CI, 0.91-1.14; P=0.732). The effects of sleep duration differed by gender, location of the population, and definitions of short or long sleep duration. Meta regression analysis including seven variables did not find the sources of heterogeneity.

CONCLUSIONS

Among adults, a U-shaped relationship between habitual sleep duration and hypertension was found at the cross-sectional level. Short sleep duration was associated with a higher risk for hypertension even longitudinally. We must pay more attention to this lifestyle factor.

Dietary nutrients associated with short and long sleep duration. Data from a nationally representative sample

Short sleep duration is associated with weight gain and obesity, diabetes, cardiovascular disease, psychiatric illness, and performance deficits. Likewise, long sleep duration is also associated with poor physical and mental health. The role of a healthy diet in habitual sleep duration represents a largely unexplored pathway linking sleep and health. This study evaluated associations between habitual sleep parameters and dietary/nutritional variables obtained via the National Health and Nutrition Examination Survey (NHANES), 2007-2008. We hypothesized that habitual very short (<5h) short (5-6h) and long (9+h) sleep durations are associated with intake of a number of dietary nutrient variables. Overall, energy intake varied across very short (2036kcal), short (2201kcal), and long (1926kcal) sleep duration, relative to normal (2151kcal) sleep duration (p=0.001). Normal sleep duration was associated with the greatest food variety (17.8), compared to very short (14.0), short (16.5) and long (16.3) sleep duration (p<0.001). Associations between sleep duration were found across nutrient categories, with significant associations between habitual sleep duration and proteins, carbohydrates, vitamins and minerals. In stepwise analyses, significant contributors of unique variance included theobromine (long sleep RR=0.910, p<0.05), vitamin C (short sleep RR=0.890, p<0.05), tap water (short sleep RR=0.952, p<0.001; very short (<5h) sleep RR=0.941, p<0.05), lutein+zeaxanthin (short sleep RR=1.123, p<0.05), dodecanoic acid (long sleep RR=0.812, p<0.05), choline (long sleep RR=0.450, p=0.001), lycopene (very short (<5h) sleep RR=0.950, p<0.05), total carbohydrate (very short (<5h) sleep RR=0.494, p<0.05; long sleep RR=0.509, p<0.05), selenium (short sleep RR=0.670, p<0.01) and alcohol (long sleep RR=1.172, p<0.01). Overall, many nutrient variables were associated with short and/or long sleep duration, which may be explained by differences in food variety. Future studies should assess whether these associations are due to appetite dysregulation, due to short/long sleep and/or whether these nutrients have physiologic effects on sleep regulation. In addition, these data may help us better understand the complex relationship between diet and sleep and the potential role of diet in the relationship between sleep and obesity and other cardiometabolic risks.

Associations of chronotype and sleep with cardiovascular diseases and type 2 diabetes

In this study, the authors analyzed whether chronotypes, sleep duration, and sleep sufficiency are associated with cardiovascular diseases and type 2 diabetes by using the National FINRISK Study 2007 data (N = 6258), being a representative sample of the population aged 25 to 74 living in five areas of Finland. Health status assessments and laboratory measurements from the participants (N = 4589) of the DILGOM substudy were used for the detailed analysis of chronotype. Evening types had a 2.5-fold odds ratio for type 2 diabetes (p < .01) as compared with morning types, the association being independent of sleep duration and sleep sufficiency. Evening types had a 1.3-fold odds ratio for arterial hypertension (p < .05 after controlling for sleep duration or sleep sufficiency), a faster resting heart rate and a lower systolic blood pressure (both p < .01), and lower levels of serum total cholesterol and low-density lipoprotein cholesterol (both p < .0001) than morning types. There were significant 1.2- to 1.4-fold odds ratios for arterial hypertension among those with long or short sleep durations or reduced sleep sufficiency. To conclude, the behavioral trait towards eveningness is suggested to predispose individuals to type 2 diabetes in particular, whereas compromised sleep is robustly associated with arterial hypertension.

Modifiable factors associated with sleep dysfunction in adults with heart failure

BACKGROUND

Sleep dysfunction contributes to poor quality of life in adults with heart failure (HF). The purpose of this study was to identify factors associated with sleep dysfunction that may be modifiable.

METHODS

Data were collected from 266 subjects enrolled from three sites in the U.S. Sleep dysfunction was measured over the past month with the Pittsburgh sleep quality index, using a score > 10 to indicate sleep dysfunction. Potentially modifiable clinical, behavioral, and psychological factors thought to be associated with sleep dysfunction were analyzed with hierarchical logistic regression analysis.

RESULTS

When covariates of age, gender, race, data collection site, and New York Heart Association (NYHA) functional class were entered on the first step, only NYHA was a significant correlate of sleep dysfunction. When the clinical, behavioral, and psychological factors were entered, correlates of sleep dysfunction were the number of drugs known to cause daytime somnolence (OR = 2.08), depression (OR = 1.83), worse overall perceived health (OR = 1.64), and better sleep hygiene (OR = 1.40). Although most (54%) subjects had sleep disordered breathing (SDB), SDB was not a significant predictor of sleep dysfunction.

DISCUSSION

Factors associated with sleep dysfunction in HF include medications with sleepiness as a side-effect, depression, poorer health perceptions, and better sleep hygiene. Sleep dysfunction may motivate HF patients to address sleep hygiene. Eliminating medications with sleepiness as a side-effect, treating depression and perceptions of poor health may improve sleep quality in HF patients.

The Epidemiology of Sleep Quality, Sleep Patterns, Consumption of Caffeinated Beverages, and Khat Use among Ethiopian College Students

Objective. To evaluate sleep habits, sleep patterns, and sleep quality among Ethiopian college students; and to examine associations of poor sleep quality with consumption of caffeinated beverages and other stimulants. Methods. A total of 2,230 undergraduate students completed a self-administered comprehensive questionnaire which gathered information about sleep complaints, sociodemographic and lifestyle characteristics,and theuse of caffeinated beverages and khat. We used multivariable logistic regression procedures to estimate odds ratios for the associations of poor sleep quality with sociodemographic and behavioral factors. Results. Overall 52.7% of students were classified as having poor sleep quality (51.8% among males and 56.9% among females). In adjusted multivariate analyses, caffeine consumption (OR = 1.55; 95% CI: 1.25–1.92), cigarette smoking (OR = 1.68; 95% CI: 1.06–2.63), and khat use (OR = 1.72, 95% CI: 1.09–2.71) were all associated with increased odds of long-sleep latency (>30 minutes). Cigarette smoking (OR = 1.74; 95% CI: 1.11–2.73) and khat consumption (OR = 1.91; 95% CI: 1.22–3.00) were also significantly associated with poor sleep efficiency (<85%), as well as with increased use of sleep medicine. Conclusion. Findings from the present study demonstrate the high prevalence of poor sleep quality and its association with stimulant use among college students. Preventive and educational programs for students should include modules that emphasize the importance of sleep and associated risk factors.

Sleep disturbances as nontraditional risk factors for development and progression of CKD: review of the evidence

Despite the high prevalence and enormous public health implications of chronic kidney disease (CKD), the factors responsible for its development and progression are incompletely understood. To date, only a few studies have attempted to objectively characterize sleep in patients with CKD prior to kidney failure, but emerging evidence suggests a high prevalence of sleep disorders, particularly obstructive sleep apnea. Laboratory and epidemiologic studies have shown that insufficient sleep and poor sleep quality promote the development and exacerbate the severity of 3 important risk factors for CKD, namely hypertension, type 2 diabetes, and obesity. In addition, sleep disturbances might have a direct effect on CKD through chronobiological alterations in the renin-angiotensin-aldosterone system and sympathetic nervous system activation. The negative impact of sleep disorders on vascular compliance and endothelial function also may have a deleterious effect on CKD. Sleep disturbances therefore may represent a novel risk factor for the development and progression of CKD. Optimizing sleep duration and quality and treating sleep disorders may reduce the severity and delay the progression of CKD.

Short sleep duration and increased risk of hypertension: a primary care medicine investigation

OBJECTIVES

Compelling evidence from laboratory-based and population-based studies link sleep loss to negative cardiovascular health outcomes. However, little is known about the association between sleep duration and hypertension in primary care health settings, independently of other well controlled clinical and biochemical characteristics. We investigated the association between sleep duration and the prevalence of hypertension adjusting for 21 potential confounding factors in a noncontrolled primary care sample.

METHODS

The sample included 1046 French adults older than 40 years (mean age, 55.5 years), who visited any of the general practitioners of primary care centers in the Paris area. Blood pressure (BP) readings, blood samples and standardized health and sleep questionnaires were performed on each participant. Hypertension inclusion criteria were either high BP measurements (SBP ≥ 140 mmHg or DBP ≥ 90 mmHg) or the use of antihypertensive medications. Sleep duration was recorded as the self-reported average number of hours of sleep per night during the week. Logistic regressions were performed to test the association between hypertension and sleep duration adjusted for sociodemographic, clinical, biochemical, lifestyle, psychological and sleep disorder covariates.

RESULTS

Compared to the group sleeping 7 h, individuals sleeping 5 h or less had an increased odds ratio (OR) for the prevalence of hypertension [OR = 1.80, 95% confidence interval (1.06-3.05)], after adjusting for 21 potential confounders which did not markedly attenuate this association.

CONCLUSION

Our data provide further epidemiologic evidence that with no specific selection in primary care medicine, usual short-sleep duration increases the risk of hypertension prevalence in adults over 40 years.

Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment

There are three mechanisms that may contribute to the health, performance, and safety problems associated with night-shift work: (1) circadian misalignment between the internal circadian clock and activities such as work, sleep, and eating, (2) chronic, partial sleep deprivation, and (3) melatonin suppression by light at night. The typical countermeasures, such as caffeine, naps, and melatonin (for its sleep-promoting effect), along with education about sleep and circadian rhythms, are the components of most fatigue risk-management plans. We contend that these, while better than nothing, are not enough because they do not address the underlying cause of the problems, which is circadian misalignment. We explain how to reset (phase-shift) the circadian clock to partially align with the night-work, day-sleep schedule, and thus reduce circadian misalignment while preserving sleep and functioning on days off. This involves controlling light and dark using outdoor light exposure, sunglasses, sleep in the dark, and a little bright light during night work. We present a diagram of a sleep-and-light schedule to reduce circadian misalignment in permanent night work, or a rotation between evenings and nights, and give practical advice on how to implement this type of plan.

Acupuncture for insomnia

BACKGROUND

Although conventional non-pharmacological and pharmacological treatments for insomnia are effective in many people, alternative therapies such as acupuncture are widely practised. However, it remains unclear whether current evidence is rigorous enough to support acupuncture for the treatment of insomnia.

OBJECTIVES

To determine the efficacy and safety of acupuncture for insomnia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, Dissertation Abstracts International, CINAHL, AMED, the Traditional Chinese Medical Literature Analysis and Retrieval System (TCMLARS), the World Health Organization (WHO) Trials Portal (ICTRP) and relevant specialised registers of the Cochrane Collaboration in October 2011. We screened reference lists of all eligible reports and contacted trial authors and experts in the field.

SELECTION CRITERIA

Randomised controlled trials evaluating any form of acupuncture for insomnia. They compared acupuncture with/without additional treatment against placebo or sham or no treatment or same additional treatment. We excluded trials that compared different acupuncture methods or acupuncture against other treatments.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias. We used odds ratio (OR) and mean difference for binary and continuous outcomes respectively. We combined data in meta-analyses where appropriate.

MAIN RESULTS

Thirty-three trials were included. They recruited 2293 participants with insomnia, aged 15 to 98 years, some with medical conditions contributing to insomnia (stroke, end-stage renal disease, perimenopause, pregnancy, psychiatric diseases). They evaluated needle acupuncture, electroacupuncture, acupressure or magnetic acupressure.Compared with no treatment (two studies, 280 participants) or sham/placebo (two studies, 112 participants), acupressure resulted in more people with improvement in sleep quality (compared to no treatment: OR 13.08, 95% confidence interval (CI) 1.79 to 95.59; compared to sham/placebo: OR 6.62, 95% CI 1.78 to 24.55). However, when assuming that dropouts had a worse outcome in sensitivity analysis the beneficial effect of acupuncture was inconclusive. Compared with other treatment alone, acupuncture as an adjunct to other treatment might marginally increase the proportion of people with improved sleep quality (13 studies, 883 participants, OR 3.08, 95% CI 1.93 to 4.90). On subgroup analysis, only needle acupuncture but not electroacupuncture showed benefits. All trials had high risk of bias and were heterogeneous in the definition of insomnia, participant characteristics, acupoints and treatment regimen. The effect sizes were generally small with wide confidence intervals. Publication bias was likely present. Adverse effects were rarely reported and they were minor.

AUTHORS' CONCLUSIONS

Due to poor methodological quality, high levels of heterogeneity and publication bias, the current evidence is not sufficiently rigorous to support or refute acupuncture for treating insomnia. Larger high-quality clinical trials are required.

Hypertension in developing countries

Data from different national and regional surveys show that hypertension is common in developing countries, particularly in urban areas, and that rates of awareness, treatment, and control are low. Several hypertension risk factors seem to be more common in developing countries than in developed regions. Findings from serial surveys show an increasing prevalence of hypertension in developing countries, possibly caused by urbanisation, ageing of population, changes to dietary habits, and social stress. High illiteracy rates, poor access to health facilities, bad dietary habits, poverty, and high costs of drugs contribute to poor blood pressure control. The health system in many developing countries is inadequate because of low funds, poor infrastructure, and inexperience. Priority is given to acute disorders, child and maternal health care, and control of communicable diseases. Governments, together with medical societies and non-governmental organisations, should support and promote preventive programmes aiming to increase public awareness, educate physicians, and reduce salt intake. Regulations for the food industry and the production and availability of generic drugs should be reinforced.

Short sleep duration is associated with hypertension risk among adults: a systematic review and meta-analysis

A number of studies have reported that sleep duration might have an important role in the development of hypertension. However, the results have been inconsistent. In this study, a meta-analysis was performed to clarify the association between sleep duration and hypertension risk. PubMed, Embase and ISI web of science databases updated on 28 October 2011 were searched for eligible publications. Pooled odds ratio (OR) or relative risk (RR) with 95% confidence intervals (CI) was calculated using a random- or fixed-effect model. Six prospective (N=9959) and seventeen cross-sectional (N=105432) studies were identified for the data analysis on sleep duration. The results indicated that short sleep duration was associated with an increased risk of prevalent hypertension (OR=1.20, 95% CI: 1.09-1.32, P<0.001), especially among subjects younger than 65 years and females. In addition, short sleep duration was also associated with an increased risk of incident hypertension among subjects younger than 65 years (RR=1.33, 95% CI: 1.11-1.61, P=0.002). Overall, there was a significant association between long sleep duration and the risk of prevalent hypertension (OR=1.11, 95% CI: 1.05-1.17, P<0.001). Further subgroup analysis also suggested a significant association between long sleep duration and the risk of prevalent hypertension among subjects younger than 65 years (OR=1.12, 95% CI: 1.06-1.19, P<0.001). The present meta-analysis indicated that short sleep duration was associated with an increased risk of hypertension in the overall polulation and incident hypertension among subjects younger than 65 years. In addition, long sleep duration might be associated with a risk of prevalent hypertension, especially among subjects younger than 65 years.

Short sleep duration and its association with energy metabolism

A growing body of observational evidence suggests that short sleep duration is a risk factor for the development of obesity. Although increased energy intake is the most prevailing causal explanation for this association, we should also consider possible effects on energy metabolism to understand fully the potential impact of short sleep duration on the regulation of energy balance. We performed a search of the literature from 1970 to 2011, including original papers, investigating the relation between short sleep and energy metabolism in animals and humans. Although the limited number of experimental studies in humans precludes any definitive conclusions about causality, short sleep duration does not seem to substantially affect total daily energy expenditure, nor is there sufficient evidence in support of any meaningful effect of restricted sleep on the specific components of energy metabolism (i.e. resting metabolic rate, intentional as well as unintentional physical activity, diet-induced thermogenesis, and substrate utilization). As studies on rats suggest that other factors that can potentially influence energy metabolism could be affected (i.e. hormonal systems and thermoregulation), we included these factors in our literature search and found some indications in support of an up-regulation of thyroid hormones and glucocorticoids as well as increased heat dissipation following total or severe sleep deficit. Although we found some evidence also in humans that suggests a possible effect on energy metabolism, the limitations of the studies make it difficult to draw conclusions on the effect of short sleep on energy metabolism under relevant free living conditions. To explore this area further, more studies using suitable methodology under relevant conditions to mimic real-life situations are needed.

Sleep: a health imperative

Chronic sleep deficiency, defined as a state of inadequate or mistimed sleep, is a growing and underappreciated determinant of health status. Sleep deprivation contributes to a number of molecular, immune, and neural changes that play a role in disease development, independent of primary sleep disorders. These changes in biological processes in response to chronic sleep deficiency may serve as etiological factors for the development and exacerbation of cardiovascular and metabolic diseases and, ultimately, a shortened lifespan. Sleep deprivation also results in significant impairments in cognitive and motor performance which increase the risk of motor vehicle crashes and work-related injuries and fatal accidents. The American Academy of Sleep Medicine and the Sleep Research Society have developed this statement to communicate to national health stakeholders the current knowledge which ties sufficient sleep and circadian alignment in adults to health.

Sociodemographic and cultural determinants of sleep deficiency: implications for cardiometabolic disease risk

Sleep is a biological imperative associated with cardiometabolic disease risk. As such, a thorough discussion of the sociocultural and demographic determinants of sleep is warranted, if not overdue. This paper begins with a brief review of the laboratory and epidemiologic evidence linking sleep deficiency, which includes insufficient sleep and poor sleep quality, with increased risk of chronic cardiometabolic diseases such as obesity, diabetes and hypertension. Identification of the determinants of sleep deficiency is the critical next step to understanding the role sleep plays in human variation in health and disease. Therefore, the majority of this paper describes the different biopsychosocial determinants of sleep, including age, gender, psychosocial factors (depression, stress and loneliness), socioeconomic position and race/ethnicity. In addition, because sleep duration is partly determined by behavior, it will be shaped by cultural values, beliefs and practices. Therefore, possible cultural differences that may impact sleep are discussed. If certain cultural, ethnic or social groups are more likely to experience sleep deficiency, then these differences in sleep could increase their risk of cardiometabolic diseases. Furthermore, if the mechanisms underlying the increased risk of sleep deficiency in certain populations can be identified, interventions could be developed to target these mechanisms, reduce sleep differences and potentially reduce cardiometabolic disease risk.

Timing and duration of sleep and meals in obese and normal weight women. Association with increase blood pressure

The aim was to evaluate the efficiency and duration of sleep and meals in normal-weight and obese women and the impact of these factors on metabolic syndrome (MetS) variables. The study was conducted in 70 women, normal-weight women (n=20) and obese women (n=50). Anthropometric variables, plasma glucose, lipids and ghrelin concentrations were determined. Blood pressure measurement was performed before lunch and before dinner for a week on alternate days. Subjects were instructed to keep a sleep and feeding diary. In general, obese women displayed longer and a significantly higher number of awakenings per week than normal-weight women and a higher duration of naps. Sleep efficiency was significantly lower in obese women. The higher intake in energy in the obese women was due to snacking differences. Moreover, higher sleep efficiency was correlated with a decrease in the diastolic blood pressure evening/morning ratio. Interestingly, among normal-weight women, visceral fat increased with the number of awakenings while plasma ghrelin was inversely correlated with meal duration (P=0.027). In conclusion, obese women had lower sleep efficiency, ate more quickly and spent more time eating and sleeping during the daytime hours than normal-weight women. Of note, sleep efficiency was associated with MetS features. Further interventions in obesity could include educating patients in food timing and in healthier sleep-hygiene practices, helping them to modify bad sleep habits.

Impact of sleepiness and sleep deficiency on public health--utility of biomarkers

Sleep disorders and sleep deficiency are important causes of adverse health effects and increased mortality in the United States and worldwide. Sleep deficiency can also result in myriad adverse behavioral consequences, including profound sleepiness, cognitive slowing, automatic behavior, attentional failures and performance degradation, errors, and accidents. It is important to recognize that sleepiness and sleep deficiency are not synonymous.