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

Sleep duration and ambulatory blood pressure in black and white adolescents

Self-reported short sleep duration is linked to higher blood pressure and incident hypertension in adults. Few studies have examined sleep and blood pressure in younger samples. We evaluated the associations between actigraphy-assessed time spent asleep and ambulatory blood pressure in adolescents. Participants were 246 black and white adolescents (mean age: 15.7 years) who were free from cardiovascular or kidney disease and were not taking sleep, cardiovascular, or psychiatric medications. Sleep duration and efficiency were assessed with in-home wrist actigraphy and sleep diaries across 1 week; ambulatory blood pressure monitoring was used to obtain 24-hour, sleep, and wake blood pressure, as well as sleep:wake blood pressure ratios across 2 full days and nights. Results showed that shorter actigraphy-assessed sleep across 1 week was related to higher 48-hour blood pressure and higher nighttime blood pressure. Shorter sleep was also related to a higher systolic blood pressure sleep:wake ratio. These results were independent of age, race, sex, and body mass index. Follow-up analyses by race revealed that associations between sleep duration and blood pressure were largely present in white, but not black, adolescents. These data are consistent with the hypothesis that the cardiovascular consequences of short sleep may begin as early as adolescence.

Does inadequate sleep play a role in vulnerability to obesity?

The prevalence of obesity is increasing rapidly worldwide, which is cause for concern because obesity increases the risk of cardiovascular disease and diabetes, reduces life expectancy, and impairs quality of life. A better understanding of the risk factors for obesity is therefore a critical global health concern, and human biologists can play an important role in identifying these risk factors in various populations. The objective of this review is to present the evidence that inadequate sleep may be a novel risk factor associated with increased vulnerability to obesity and associated cardiometabolic disease. Experimental studies have found that short-term sleep restriction is associated with impaired glucose metabolism, dysregulation of appetite, and increased blood pressure. Observational studies have observed cross-sectional associations between short sleep duration (generally <6 h per night) and increased body mass index or obesity, prevalent diabetes, and prevalent hypertension. Some studies also reported an association between self-reported long sleep duration (generally >8 h per night) and cardiometabolic disease. A few prospective studies have found a significant increased risk of weight gain, incident diabetes, and incident hypertension associated with inadequate sleep. Given the potential link between inadequate sleep and obesity, a critical next step is to identify the social, cultural, and environmental determinants of sleep, which would help to identify vulnerable populations. Future human biology research should consider variation in sleep characteristics among different populations and determine whether the associations between sleep and obesity observed in Western populations persist elsewhere.

Short sleep duration is independently associated with overweight and obesity in Quebec children

OBJECTIVE

To investigate the association of sleep duration with adiposity and to determine if caloric intake and physical activity mediate this relationship.

METHODS

The Quebec Adiposity and Lifestyle Investigation in Youth (QUALITY) study is an ongoing longitudinal investigation of Caucasian children with at least one obese biological parent. Children (n = 550) with an average age of 9.6 years (SD = 0.9) who provided complete data at baseline were included in the cross-sectional analyses. Objective measures of adiposity (BMI Z-score, waist circumference, percent body fat measured by dual-energy X-ray absorptiometry), sleep duration and physical activity (accelerometer over 7 days), and diet (24-hour food recalls) were collected. Children were categorized into 4 groups according to sleep duration: < 10 hours, 10-10.9 hours, 11-11.9 hours, and > or = 12 hours of sleep per night.

RESULTS

We observed a U-shaped relationship between sleep duration and all adiposity indices. None of energy intake, snacking, screen time or physical activity intensity differed significantly between sleep categories. After adjusting for age, sex, Tanner stage, highest educational level of the parents, total annual family income, and parental BMI, only short-duration sleepers (< 10 hours) had an increased odds of overweight/obesity (OR 2.08, 95% CI 1.16-3.67). Addition of total energy intake and physical activity to the model did not change the association substantially (OR 2.05, 95% CI 1.15-3.63).

CONCLUSION

The present study provides evidence that short sleep duration is a risk factor for overweight and obesity in children, independent of potential covariates. These results further emphasize the need to add sleep duration to the determinants of obesity.

Schlaf und Sport

Der Schlaf ist eine wichtige Ressource für das psychische und physische Wohlbefinden. Die Erkenntnisse aus der Schlafforschung spielten jedoch in der Sportwissenschaft bislang nur eine untergeordnete Rolle. Nach einer kurzen Einführung zur physiologischen Erfassung von Schlaf werden in diesem Beitrag drei Bereiche aufgeführt, die fruchtbare Verknüpfungen zwischen Schlaf- und Sportwissenschaft aufweisen. Im ersten Bereich wird auf die schlafbegleitende Konsolidierung von motorischen Gedächtnisinhalten eingegangen. Dieser eher grundlagenorientierte Forschungszweig beleuchtet den Zusammenhang zwischen der Aneignung bzw. Optimierung von motorischen Fertigkeiten und verschiedenen Schlafstadien und Schlafparametern (z. B. Schlafspindeln). In dem zweiten Bereich geht es um den Schlaf vor sportlichen Wettkämpfen. Für den Sport liegt eine Vielzahl von anekdotischen Belegen über eine schlecht geschlafene Nacht vor einem sportlichen Wettkampf vor. Systematische Erhebungen existieren jedoch kaum. Anhand verschiedener Studien sollen Aspekte geklärt werden, die die Ursachen und Häufigkeiten von schlechtem Schlaf vor Wettkämpfen und die Auswirkung auf die Wettkampfleistung betreffen. Der dritte Bereich widmet sich dem Einfluss von körperlicher Aktivität auf den Schlaf. Es zeigt sich, dass der Sport einen positiven Effekt auf den Schlaf bei Menschen mit Schlafstörung aufweist. Diese Befunde weisen auf einen therapeutischen Ansatz für Sportwissenschaftler in der Schlafmedizin. Abschließend werden sportpraktische Implikationen erörtert und Perspektiven auf weitere Forschungsfragen eröffnet.

Moderate exercise plus sleep education improves self-reported sleep quality, daytime mood, and vitality in adults with chronic sleep complaints: a waiting list-controlled trial

Research indicates that physical exercise can contribute to better sleep quality. This study investigates the six-week influence of a combined intervention on self-rated sleep quality, daytime mood, and quality of life. A nonclinical sample of 114 adults with chronic initiating and the maintaining of sleep complaints participated in the study. The intervention group of 70 adults underwent moderate physical exercise, conducted weekly, plus sleep education sessions. Improvements among participants assigned to the intervention group relative to the waiting-list control group (n = 44) were noted for subjective sleep quality, daytime mood, depressive symptoms and vitality. Derived from PSQI subscores, the intervention group reported increased sleep duration, shortened sleep latency, fewer awakenings after sleep onset, and overall better sleep efficiency compared to controls. The attained scores were well sustained and enhanced over a time that lasted through to the follow-up 18 weeks later. These findings have implications in treatment programs concerning healthy lifestyle approaches for adults with chronic sleep complaints.

Can personal exposures to higher nighttime and early-morning temperatures increase blood pressure?

Environmental temperatures are inversely related to BP; however, the effects of short-term temperature changes within a 24-hour period and measured with high accuracy at the personal level have not been described. Fifty-one nonsmoking patients living in the Detroit area had up to 5 consecutive days of 24-hour personal-level environmental temperature (PET) monitoring along with daily cardiovascular measurements, including BP, performed mostly between 5 pm and 7 pm during summer and/or winter periods. The associations between hour-long mean PET levels during the previous 24 hours with the outcomes were assessed by linear mixed models. Accounting for demographics, environmental factors, and monitoring compliance, systolic and diastolic BP were positively associated with several hour-long PET measurements ending from 10 to 15 hours beforehand. During this time, corresponding mostly to a period starting from between 1 am and 3 am to ending between 7 am and 9 am, an increase of 1°C was associated with a 0.81 mm Hg to 1.44 mm Hg and 0.59 mm Hg to 0.83 mm Hg elevation in systolic and diastolic BP, respectively. Modestly warmer, commonly encountered PET levels posed a clinically meaningful effect (eg, a 6.95 mm Hg systolic pressure increase per interquartile range (4.8°C) elevation at lag hour 10). Community-level outdoor ambient temperatures were not related to BP. The authors provide the first evidence that personal exposure to warmer nighttime and early-morning environmental temperatures might lead to an increase in BP during the ensuing day.

Decreased slow wave sleep increases risk of developing hypertension in elderly men

The importance of sleep to health and cardiovascular disease has become increasingly apparent. Sleep-disordered breathing, sleep duration, and sleep architecture may all influence metabolism and neurohormonal systems, yet no previous study has evaluated these sleep characteristics concurrently in relation to incident hypertension. Our objective was to determine whether incident hypertension is associated with polysomnography measures of sleep-disordered breathing, sleep duration, and sleep architecture in older men. Participants were 784 community-dwelling, ambulatory men ≥65 years of age (mean age: 75.1±4.9 years) from the Outcomes of Sleep Disorders in Older Men Study who did not have hypertension at the time of their in-home polysomnography sleep studies (2003-2005) and who returned for follow-up (2007-2009). Of 784 older men included in this report, 243 met criteria for incident hypertension after a mean follow-up of 3.4 years. In unadjusted analyses, incident hypertension was associated with increased hypoxemia, increased sleep stages N1 and N2, and decreased stage N3 (slow wave sleep [SWS]). After adjustment for age, nonwhite race, study site, and body mass index, the only sleep index to remain significantly associated with incident hypertension was SWS percentage (odds ratio for lowest to highest quartile of SWS: 1.83 [95% CI: 1.18 to 2.85]). No attenuation of this association was seen after accounting for sleep duration, sleep fragmentation, and indices of sleep-disordered breathing. Percentage time in SWS was inversely associated with incident hypertension, independent of sleep duration and fragmentation, and sleep-disordered breathing. Selective deprivation of SWS may contribute to adverse blood pressure in older men.

Association between habitual sleep duration and blood pressure and clinical implications: a systematic review

Elucidation of the association between short sleep duration and elevated blood pressure has implications for assessing and managing hypertension in adults.

OBJECTIVE

To assess the relationship between sleep duration and blood pressure, and its role in the etiology of hypertension.

METHODS

On a systematic search from MEDLINE, EMBASE, CINAHL, PEDro, PsychINFO and grey literature were included articles with participants over 18 years, reported sleep duration, measured blood pressure or diagnosed hypertension, and the relationship between sleep duration and blood pressure was analyzed.

RESULTS

Of 2522 articles initially identified, 11 studies met the inclusion criteria. Sample sizes ranged from 505 to 8860 (aged ≥ 20-98 years). Five studies (aged ≥ 58-60 years) determined that sleep duration and blood pressure were unrelated. In younger adults, five studies reported an association between short sleep duration and hypertension before adjustment for confounding variables; only the findings from one study remained significant after adjustment. Two studies supported a sex association; women who sleep less than 5-6 h nightly are at greater risk of developing hypertension.

CONCLUSION

Sleep duration and blood pressure are associated in both women and adults under 60 years. Controlled studies are needed to elucidate confounding factors and the degree to which sleep profiles could augment diagnosis of hypertension and sleep recommendations to prevent or manage hypertension.

Gender-specific association of sleep duration with blood pressure in rural Chinese adults

BACKGROUND

There are limited data about the role of gender on the relationship between sleep duration and blood pressure (BP) from rural populations.

METHODS

We conducted a cross-sectional rural population-based study. This report includes 1033 men and 783 women aged 18-65 years from a cohort of twins enrolled in Anhui, China, between 2005 and 2008. Sleep duration was derived from typical bedtime, wake-up time, and sleep latency as reported on a standard sleep questionnaire. Primary outcomes included measured systolic blood pressure (SBP) and diastolic blood pressure (DBP). High blood pressure (HBP) was defined as SBP ⩾130 mmHg, DBP ⩾85 mmHg, or physician diagnosed hypertension. Linear and logistic regression models were used to assess gender-specific associations between sleep duration and BP or HBP, respectively, with adjustment for known risk factors including adiposity and sleep-related disorder risk from the questionnaires. Generalized estimating equations were used to account for intra-twin pair correlations.

RESULTS

Compared with those sleeping 7 to <9h, women sleeping <7h had a higher risk of HBP (odds ratios [ORs] 3.0, 95% confidence interval [CI], 1.4-6.6); men sleeping ⩾9h had a higher risk of HBP (ORs=1.5, 95%CI: 1.1-2.2).

CONCLUSIONS

Among rural Chinese adults, a gender-specific association of sleep duration with BP exists such that HBP is associated with short sleep duration in women and long sleep duration in men. Longitudinal studies are needed to further examine the temporal relationship and biological mechanisms underlying sleep duration and BP in this population. Our findings underscore the potential importance of appropriate sleep duration for optimal blood pressure.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Associations between sleep disorders, sleep duration, quality of sleep, and hypertension: results from the National Health and Nutrition Examination Survey, 2005 to 2008

Sleep is a contributing factor to optimal health and vitality. However, to date, no national study has evaluated the simultaneous relationship between sleep disorders, quality, and duration with hypertension. Using data from National Health and Nutrition Examination Survey (NHANES) (2005 to 2008), hypertension was defined by current use of antihypertensive medication or systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg. Self-reported sleep disorders and duration were categorized from a single household interview question, and sleep quality was determined from several questions on sleeping habits. The prevalence of hypertension was 30.2% and 7.5%, and 33.0% and 52.1% reported having sleep disorders, short sleep, and poor sleep, respectively. After adjustment for demographic characteristics and comorbidities, having sleep disorders only was not significantly associated with hypertension (odds ratio [OR], 1.65; 95% confidence interval [CI], 0.73-3.77). However, this association was modified by sleep duration: significant associations were observed among adults with concurrent sleep disorders and short sleep (OR, 2.30; 95% CI, 1.49-3.56) and with sleep disorders, short sleep, and poor sleep (OR, 1.84; 95% CI, 1.13-2.98). These findings indicate an association between a combination of sleep problems and hypertension, but prospective studies are needed to understand the complex interplay between them.

No elevated plasma catecholamine levels during sleep in newly diagnosed, untreated hypertensives

The sympatho-adrenergic system is highly involved in regulating sleep, wake and arousal states, and abnormalities in this system are regarded as a key factor in the development and progression of arterial hypertension. While hypertension is associated with a hyperadrenergic state during wakefulness, the effect of hypertension on plasma-catecholamine levels during sleep is not yet known. Twelve young participants with newly diagnosed, untreated hypertension and twelve healthy controls slept for 7 hours in the sleep laboratory. Before and after sleep, subjects rested in a supine position for 3-h periods of wakefulness. We sampled blood at a fast rate (1/10 min) and monitored blood pressure and heart rate continuously. We show that plasma NE and E levels did not differ between hypertensives and normotensive during sleep as well as before and after sleep. Blood pressure was higher in hypertensives, reaching the largest group difference in the morning after sleep. Unlike in the normotensives, in the hypertensive participants the morning rise in blood pressure did not correlate with the rise in catecholamine levels at awakening. Our results suggest that hypertension in its early stages is not associated with a strong hyperadrenergic state during sleep. In showing a diminished control of blood pressure through sympatho-adrenergic signals in hypertensive participants, our data point towards a possible involvement of dysfunctional sleep-related blood pressure regulation in the development of hypertension.

Modern sedentary activities promote overconsumption of food in our current obesogenic environment

Achieving body-weight stability is certainly challenging in today's obesogenic environment. Every day we are surrounded and affected by stimuli that act on our behaviour. A common feature of these stimuli is that they increase our comfort and well-being, but unfortunately they promote a positive caloric balance. Intriguingly, the preponderance of sedentary lifestyles is not only a matter of the amount of calories expended. A careful examination of modern sedentary activities reveals that they also promote overconsumption of food. This is particularly the case with television viewing, video game playing, cognitive working, music listening and short sleeping. Moreover, the increased food intake in the absence of hunger observed with the practice of these modern-life activities emphasizes that the hedonic value of food intake plays an important role. These observations suggest that our quest for reward and pleasure is not fine tuned to our biology, and the development of coping strategies is needed.

Relationship of sleep quantity and quality with 24-hour urinary catecholamines and salivary awakening cortisol in healthy middle-aged adults

OBJECTIVES

a. Explore the stability in sleep/wake patterns of middle-aged adults over a 3-year follow-up period. b. Explore the relationship between objectively measured sleep indices, urinary catecholamines, and salivary cortisol.

DESIGN

Naturalistic follow-up for sleep/wake patterns (n = 114) by 2-week sleep log and cross-sectional design for objective sleep assessments and hormonal measures (n = 96) at follow-up period nearly 3 years after baseline measurements.

SETTING

Community

PARTICIPANTS

Healthy middle-aged adults

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

There were high correlations between baseline and follow-up period (2.6 ± 0.5 years) on sleep/wake patterns (r = 0.6-0.79) as measured by 2-week sleep log. For wave 2 cross-sectional study, objective poor sleepers (3-day actigraphy sleep efficiency < 85%) had a higher 24-h urinary norepinephrine (NE) level (205.7 ± 105 nmol/d vs 162.1 ± 55.6 nmol/d, P = 0.03) and a nearly significantly higher 24-h urinary epinephrine (E) level (P = 0.12) than good sleepers. There were no differences in 3-day mean salivary awakening cortisol and 24-h urinary catecholamines (NE and E) between short and normal/long sleepers. Linear regression results, however, showed that shorter time in bed and actual sleep time, longer sleep onset latency, and lower sleep efficiency were correlated with higher 24-h urinary E and NE (all P < 0.05) but not salivary cortisol. The effect of poor sleep quality on 24-h urinary catecholamines was stronger in males than females.

CONCLUSIONS

Increased sympathetic activity as measured by 24-h urinary catecholamines might play a critical role in the pathogenesis mediating the relationship of insufficient sleep (quantity and quality) with subsequent cardiovascular and metabolic complications. Salivary awakening cortisol was not associated with sleep quantity and quality in healthy middle-aged adults.

Do all sedentary activities lead to weight gain: sleep does not

PURPOSE OF REVIEW

To discuss the benefits of having a good night's sleep for body weight stability.

RECENT FINDINGS

Experimental studies have shown that short-term partial sleep restriction decreases glucose tolerance, increases sympathetic tone, elevates cortisol concentrations, decreases the satiety hormone leptin, increases the appetite-stimulating hormone ghrelin, and increases hunger and appetite. Short sleep duration might increase the risk of becoming obese, because it does not allow the recovery of a hormonal profile facilitating appetite control. Lack of sleep could also lead to weight gain and obesity by increasing the time available for eating and by making the maintenance of a healthy lifestyle more difficult. Furthermore, the increased fatigue and tiredness associated with sleeping too little could lessen one's resolve to follow exercise regimens.

SUMMARY

Short sleep duration appears to be a novel and independent risk factor for obesity. With the growing prevalence of chronic sleep restriction, any causal association between reduced sleep and obesity would have substantial importance from a public health standpoint. Future research is needed to determine whether sleep extension in sleep-deprived obese individuals will influence appetite control and/or reduce the amount of body fat.

Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence

Laboratory studies have found that short-term sleep restriction is associated with impairments in glucose metabolism, appetite regulation and blood pressure regulation. This chapter reviews the epidemiologic evidence for an association between habitual sleep duration and quality and risk of cardiometabolic diseases including obesity, diabetes and hypertension. Multiple studies observed a cross-sectional association between short sleep duration (generally <6 h per night) and increased body mass index or obesity, prevalent diabetes and prevalent hypertension. Many studies also reported an association between self-reported long sleep duration (generally >8 h per night) and cardiometabolic disease. There have been a few prospective studies and several, but not all, have found an association between short sleep and incident diabetes, hypertension and markers of cardiovascular disease. Future prospective epidemiologic studies need to include objective measures of sleep, and intervention studies are needed in order to establish a causal link between impaired or insufficient sleep and cardiometabolic disease risk.

Associations of early pregnancy sleep duration with trimester-specific blood pressures and hypertensive disorders in pregnancy

STUDY OBJECTIVES

We evaluated the influence of maternal self-reported habitual sleep duration during early pregnancy on blood pressure (BP) levels and risk of hypertensive disorders of pregnancy.

DESIGN

Prospective cohort study.

SETTING

Clinic-based study.

PARTICIPANTS

A cohort of 1,272 healthy, pregnant women.

MEASUREMENTS AND RESULTS

We abstracted maternal antenatal BP values from medical records and estimated mean BP differences across hours of sleep categories in regression models, using generalized estimating equations. Odds ratios (OR) and 95% confidence intervals (95% CIs) for pregnancy induced hypertension (PIH) and preeclampsia (PE) in relation to long and short sleep duration were estimated. Mean 1st and 2nd trimester systolic (S) and diastolic (D) BP values were similar among women reporting to be short sleepers (< or = 6 h) vs. women reporting to sleep 9 hours. However, both short and long sleep duration in early pregnancy were associated with increased mean 3rd trimester SBP and DBP. For example, mean 3rd trimester SBP was 3.72, and 2.43 mm Hg higher for women reporting < or = 6 h and 7-8 h sleep, respectively, compared with women reporting 9 h of sleep. Mean 3rd trimester SBP was 4.21 mm Hg higher for women reporting long sleep (> or = 10 h) vs. the reference group. Short and long sleep durations were associated with increased risks of PIH and PE. The ORs for very short (< 5 h) and long (> or = 10 h) sleepers were 9.52 (95% CI 1.83 to 49.40) and 2.45 (95% CI 0.74 to 8.15) for PE.

CONCLUSIONS

Our findings are consistent with a larger literature that documents elevated blood pressure and increased risks of hypertension with short and long sleep duration.

Sleep and hypertension

Ambulatory BP studies indicate that even small increases in BP, particularly nighttime BP levels, are associated with significant increases in cardiovascular morbidity and mortality. Accordingly, sleep-related diseases that induce increases in BP would be anticipated to substantially affect cardiovascular risk. Both sleep deprivation and insomnia have been linked to increases in incidence and prevalence of hypertension. Likewise, sleep disruption attributable to restless legs syndrome increases the likelihood of having hypertension. Observational studies demonstrate a strong correlation between the severity of obstructive sleep apnea (OSA) and the risk and severity of hypertension, whereas prospective studies of patients with OSA demonstrate a positive relationship between OSA and risk of incident hypertension. Intervention trials with continuous positive airway pressure (CPAP) indicate a modest, but inconsistent effect on BP in patients with severe OSA and a greater likelihood of benefit in patients with most CPAP adherence. Additional prospective studies are needed to reconcile observational studies suggesting that OSA is a strong risk factor for hypertension with the modest antihypertensive effects of CPAP observed in intervention studies.

A population-based study of reduced sleep duration and hypertension: the strongest association may be in premenopausal women

OBJECTIVES

Recent evidence indicates that reduced sleep duration may be associated with an increased risk of hypertension with possibly stronger effects among women than men. We therefore examined cross-sectional sex-specific associations of sleep duration with hypertension in a large population-based sample from the Western New York Health Study (1996<2001).

METHODS

Participants were 3027 white men (43.5%) and women (56.5%) without prevalent cardiovascular disease (median age 56 years). Hypertension was defined as blood pressure at least 140 or at least 90&mmHg or regular use of antihypertensive medication. Multivariate logistic regression analyses were performed to estimate odds ratios (ORs) of hypertension comparing less than 6&h of sleep per night versus the reference category (&6&h) while accounting for a number of potential confounders.

RESULTS

In multivariate analyses, less than 6&h of sleep was associated with a significant increased risk of hypertension compared to sleeping at least 6&h per night, only among women [OR&=&1.66 (1.09 to 2.53)]. No significant association was found among men [OR&=&0.93 (0.62 to 1.41)].In subgroup analyses by menopausal status, the effect was stronger among premenopausal women [OR&=&3.25 (1.37 to 7.76)] than among postmenopausal women [OR&=&1.49 (0.92 to 2.41)].

CONCLUSION

Reduced sleep duration, by increasing the risk of hypertension, may produce detrimental cardiovascular effects among women. The association is independent of socioeconomic status, traditional cardiovascular risk factors, and psychiatric comorbidities, and is stronger among premenopausal women. Prospective and mechanistic evidence is necessary to support causality.

Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies

BACKGROUND

Increasing evidence suggests an association between both short and long duration of habitual sleep with adverse health outcomes.

OBJECTIVES

To assess whether the population longitudinal evidence supports the presence of a relationship between duration of sleep and all-cause mortality, to investigate both short and long sleep duration and to obtain an estimate of the risk.

METHODS

We performed a systematic search of publications using MEDLINE (1966-2009), EMBASE (from 1980), the Cochrane Library, and manual searches without language restrictions. We included studies if they were prospective, had follow-up >3 years, had duration of sleep at baseline, and all-cause mortality prospectively. We extracted relative risks (RR) and 95% confidence intervals (CI) and pooled them using a random effect model. We carried out sensitivity analyses and assessed heterogeneity and publication bias.

RESULTS

Overall, the 16 studies analyzed provided 27 independent cohort samples. They included 1,382,999 male and female participants (followup range 4 to 25 years), and 112,566 deaths. Sleep duration was assessed by questionnaire and outcome through death certification. In the pooled analysis, short duration of sleep was associated with a greater risk of death (RR: 1.12; 95% CI 1.06 to 1.18; P < 0.01) with no evidence of publication bias (P = 0.74) but heterogeneity between studies (P = 0.02). Long duration of sleep was also associated with a greater risk of death (1.30; [1.22 to 1.38]; P < 0.0001) with no evidence of publication bias (P = 0.18) but significant heterogeneity between studies (P < 0.0001).

CONCLUSION

Both short and long duration of sleep are significant predictors of death in prospective population studies.

Severe obstructive sleep apnea: sleepy versus nonsleepy patients

OBJECTIVES/HYPOTHESIS

To compare demographic and polysomnographic data of sleepy versus nonsleepy severe obstructive sleep apnea (OSA) patients according to the Epworth Sleepiness Scale (ESS).

STUDY DESIGN

Retrospective cohort.

METHODS

Six hundred forty-four consecutive severe (apnea-hypopnea index [AHI] >or= 30) adult OSA patients who underwent a polysomnographic evaluation in our sleep disorders unit. ESS data were available in 569 (88.3%). Three hundred twenty-seven (57.5%) patients had ESS > 10.

RESULTS

Sleepy severe OSA patients are slightly younger and more obese than nonsleepy patients. These sleepy patients have shorter sleep latency and lower percentage of slow wave sleep. They consistently show a higher AHI, both supine and lateral AHI, have a higher number of short arousals, and a higher arousal index. They also have higher snoring loudness in the supine and both lateral positions and a lower minimal SaO(2) in rapid eye movement and non-rapid eye movement sleep. After adjusting for confounders, a logistic regression model points to apnea index as a significant prognostic factor for excessive daytime sleepiness.

CONCLUSIONS

Severe OSA sleepy patients have a syndrome that is significantly more severe than nonsleepy patients. Sleepy patients have worse sleep-related breathing parameters, and their sleep patterns are lighter and more fragmented than nonsleepy patients. Apnea index appears as an important prognostic factor for excessive daytime sleepiness.

Circadian control of mouse heart rate and blood pressure by the suprachiasmatic nuclei: behavioral effects are more significant than direct outputs

Background

Diurnal variations in the incidence of events such as heart attack and stroke suggest a role for circadian rhythms in the etiology of cardiovascular disease. The aim of this study was to assess the influence of the suprachiasmatic nucleus (SCN) circadian clock on cardiovascular function.

Methodology/Principal Findings

Heart rate (HR), blood pressure (BP) and locomotor activity (LA) were measured in circadian mutant (Vipr2^−/−) mice and wild type littermates, using implanted radio-telemetry devices. Sleep and wakefulness were studied in similar mice implanted with electroencephalograph (EEG) electrodes. There was less diurnal variation in the frequency and duration of bouts of rest/activity and sleep/wake in Vipr2^−/− mice than in wild type (WT) and short “ultradian” episodes of arousal were more prominent, especially in constant conditions (DD). Activity was an important determinant of circadian variation in BP and HR in animals of both genotypes; altered timing of episodes of activity and rest (as well as sleep and wakefulness) across the day accounted for most of the difference between Vipr2^−/− mice and WT. However, there was also a modest circadian rhythm of resting HR and BP that was independent of LA.

Conclusions/Significance

If appropriate methods of analysis are used that take into account sleep and locomotor activity level, mice are a good model for understanding the contribution of circadian timing to cardiovascular function. Future studies of the influence of sleep and wakefulness on cardiovascular physiology may help to explain accumulating evidence linking disrupted sleep with cardiovascular disease in man.

Epidemiological evidence for the links between sleep, circadian rhythms and metabolism

Epidemiological data reveal parallel trends of decreasing sleep duration and increases in metabolic disorders such as obesity, diabetes and hypertension. There is growing evidence that these trends are mechanistically related. The seasonal expression of the thrifty genotype provides a conceptual framework to connect circadian and circannual rhythms, sleep and metabolism. Experimental studies have shown sleep deprivation to decrease leptin, increase ghrelin, increase appetite, compromise insulin sensitivity and raise blood pressure. Habitually short sleep durations could lead to insulin resistance by increasing sympathetic nervous system activity, raising evening cortisol levels and decreasing cerebral glucose utilization that over time could compromise beta-cell function and lead to diabetes. Prolonged short sleep durations could lead to hypertension through raised 24-h blood pressure and increased salt retention resulting in structural adaptations and the entrainment of the cardiovascular system to operate at an elevated pressure equilibrium. Cross-sectional and longitudinal epidemiological studies have shown associations between short sleep duration and obesity, diabetes and hypertension. If metabolic changes resulting from sleep restriction function to increase body weight, insulin resistance and blood pressure then interventions designed to increase the amount and improve the quality of sleep could serve as treatments and as primary preventative measures for metabolic disorders.