Short sleep duration as an independent predictor of cardiovascular events in Japanese patients with hypertension

The relation between habitual sleep duration and blood pressure values in Japanese male subjects

BACKGROUND

Previous studies have demonstrated that sleep duration is closely associated with metabolic risk factors. However, the relationship between habitual sleep duration and blood pressure values in Japanese population has not been fully established.

METHODS

We performed a cross-sectional study of 1,670 Japanese male subjects to clarify the relationship between habitual sleep duration and blood pressure values. The study subjects were divided into four groups (<6, 6-, 7-, and ≥8 h) according to their nightly habitual sleep duration.

RESULTS

The rate of subjects with <6, 6-, 7-, and ≥8 h sleep duration was 12.0, 37.6, 38.2, and 12.2 %, respectively. Compared with the group with 7-h sleep duration (referent), the <6 and ≥8 h groups had significantly greater systolic and diastolic blood pressure values. The rate of hypertensive subjects, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg, with sleep duration of <6, 6-, 7-, and ≥8 h was 13.4, 5.7, 7.5, and 13.8 %, respectively. Compared with the group with 7-h sleep duration (referent), the multivariate odds ratios (95 % confidence interval) of the groups with <6 and ≥8 h for hypertension was 2.43 (1.40-4.20, P < 0.01) and 2.28 (1.31-3.95, P < 0.01), respectively, adjusted for conventional cardiovascular risk factors.

CONCLUSION

The present study demonstrates that both long and short habitual sleep duration were significantly associated with high blood pressure values and hypertension occurrence in Japanese male subjects.

Cardiovascular-sleep interaction in drug-naïve patients with essential grade I hypertension

Lack of nighttime blood pressure (BP) reduction by 10-20% from the mean daytime values (dipping) has been described as a distinguishing feature of essential hypertension and associated, also in normotensive subjects, with increased cardiovascular (CV) risk. Mechanisms involved in the loss of the nocturnal dip are still unclear, but involvement of autonomic nervous system (ANS) activity probably plays a crucial role. Sleep is fundamental in modulating ANS activity to maintain the physiological BP circadian rhythm, and for this reason its integrity has been widely investigated in hypertension. We investigated, under controlled conditions, the autonomic control of the CV system through an autonomic reflex screen in the awake condition and by assessment of circadian rhythm-, day-night-, time-, and state-dependent changes of BP and heart rate (HR) and associated sleep parameters in patients with a recent (≤1 yr) diagnosis of essential grade I hypertension naïve of therapy. Fourteen hypertensive patients (6 males, age: 43 ± 11 yrs; body mass index [BMI]: 24 ± 3 kg/m(2)) were compared with 28 healthy controls matched for sex, age, BMI (2 controls/patient) for cardiovascular reflex and to 8 different subjects from previous controls (6 males), comparable for age and BMI, for the day-night and nighttime CV profiles during two consecutive nights. The cardiovascular reflex screen data showed increased sympathetic effect in hypertensive patients, represented by higher overshoot of BP after Valsalva maneuver. Nighttime sleep architecture during the dark period in terms of duration, representation of sleep stages, sleep fragmentation, and incidence of arousals-periodic limb movements in sleep (PLMS) and PLMS arousals-was similar in patients and controls. Hypertensive patients displayed higher 24-h BP and HR values, but their sleep-related BP decrease was significantly reduced compared with controls. The circadian rhythms of BP and HR were intact and similar in patients and controls, coupling with the expected physiological peak time. BP and HR showed normal state-dependent modulation in hypertensive patients that, however, was higher in all sleep stages compared with controls. The lowering of systolic blood pressure (SBP) during non-rapid eye movement (NREM) sleep stages 1 and 2 and REM sleep, relative to daytime wake values, was significantly attenuated in the hypertensive group, whereas it was comparable to controls during slow-wave sleep. In hypertensive patients, analysis of sleep and CV parameters in the 90 min following sleep onset and preceding morning awakening showed normal depressor effect during the first part of the night after sleep onset and significantly higher BP rise in the hours preceding morning awakening. These findings were associated with comparable sleep architecture, sleep fragmentation, incidence of arousals, and PLMS and PLMS arousals in patients and controls. Our data suggest that drug-naïve essential grade I hypertension is associated with signs of increased vascular sympathetic response to standardized stress of the Valsalva maneuver during the awake condition, and during sleep with a non-dipping BP profile plus higher BP surge preceding morning awakening, assessable only by around-the-clock ambulatory BP monitoring, both representing additional CV risk already in early-stage hypertension and, therefore, requiring proper selection of pharmacological treatment.

Nighttime Home Blood Pressure and the Risk of Hypertensive Target Organ Damage

In ambulatory blood pressure (BP) monitoring, nighttime BP has a superior ability to predict hypertensive target organ damage than awake BP. We evaluated whether nighttime BP, assessed by a home BP monitor, was associated with hypertensive target organ damage. We measured clinic BP, out-of-clinic BP including nighttime home BP, and the urinary albumin:creatinine ratio (UACR) in 854 patients who had cardiovascular risk factors. Nighttime home BP was measured at 2:00, 3:00, and 4:00 am, in addition to clinic, awake ambulatory, nighttime ambulatory, and awake home BP. Nighttime home systolic BP (SBP) was slightly higher than nighttime ambulatory SBP (difference, 2.6 mm Hg; P <0.001). Clinic ( r =0.186), awake ambulatory ( r =0.173), nighttime ambulatory ( r =0.194), awake home ( r =0.298), and nighttime home ( r =0.311) SBPs were all associated with log-transformed UACR (all P <0.001). The correlation coefficient for the relationship between nighttime home SBP and log-transformed UACR was significantly greater than that for the relationship between nighttime ambulatory SBP and log-transformed UACR ( P <0.001). The goodness of fit of the association between SBP and UACR was improved by adding nighttime home SBP to the other SBPs ( P <0.001). Nighttime home diastolic BP also improved the goodness-of-fit of the association between diastolic BP and UACR ( P =0.001). Similar findings were observed for the left ventricular mass index in the subgroup (N=594). In conclusion, nighttime home BP is slightly different from (but comparable to) nighttime ambulatory BP. The addition of nighttime home BP to other BP measures improves the association of BP with hypertensive target organ damage.

Sleep duration, snoring habits, and cardiovascular disease risk factors in an ethnically diverse population

BACKGROUND

Lack of sleep has been associated with an increased risk for cardiovascular disease (CVD) and all-cause mortality, but the mechanisms are not fully understood. Prior research has often been conducted in select populations and has not consistently adjusted for confounders, especially psychosocial factors.

OBJECTIVE

The aims of this study were to assess the association between sleep habits and established risk factors for CVD and to evaluate potential interactions by race and gender.

METHODS

Participants were part of a CVD screening and educational outreach program in New York City. Free-living men older than 40 years and women older than 50 years (n = 371, mean age = 60 years, 57% women, 60% racial/ethnic minorities) were systematically assessed for CVD risk (including traditional, lifestyle, and psychosocial risk factors) and completed a standardized questionnaire regarding sleep habits (including sleep duration and snoring). Lipids were analyzed by validated finger-stick technology. Stress at work and at home was assessed using a validated screening tool from the INTERHEART study. Associations between participants' sleep habits and CVD risk factors/demographic factors were assessed using multivariable logistic regression.

RESULTS

The proportion of participants who reported sleeping less than 6 hours per night on average was 28%, and 52% of participants reported snoring. Sleeping less than 6 hours per night was significantly (P < .05) associated with female gender, being single, increased stress at home, increased financial stress, and low-density lipoprotein cholesterol (LDL-C) level. Gender modified the association between sleep duration and LDL-C level (P = .04): Sleeping less than 6 hours per night was significantly associated with reduced LDL-C level among women and increased LDL-C level among men. Snoring was significantly associated with low high-density lipoprotein cholesterol (HDL-C) level (<40 mg/dL for men/<50 mg/dL for women), being married, increased stress at work and at home, less than 30 minutes of exercise per day, less than 5 servings of fruits and vegetables per day, and being overweight/obese (body mass index ≥25 kg/m). The association between snoring and low HDL-C level remained significant in logistic regression models adjusted for demographic confounders (odds ratio, 1.83; 95% confidence interval, 1.06-3.19) but not after adjustment for body mass index greater than 25 kg/m.

CONCLUSIONS

Sleeping less than 6 hours per night was associated with several traditional and psychosocial CVD risk factors, and snoring was associated with low HDL-C level, likely mediated through overweight/obesity. These data may have significance for health care providers to identify individuals who may be at increased CVD risk based on sleep habits.

Incorporating the treatment of medical and psychiatric disorders in the critical care area

Critical care areas are fast moving, often chaotic, and therefore confusing, even frightening, to patients attempting to understand what has happened to them. The nurse acts to mitigate these reactions by understanding the range of possibilities that can occur with patients, including potential psychiatric issues, and serving as patient advocate to ensure that appropriate treatment is initiated. Certainly there may be other psychiatric problems not described in the preceding text. The main possibilities are covered in this article. Assessing and acting early are tools the critical care nurse uses to meet patient needs and prevent behavioral problems that can interfere with life-preserving care.

Genetic association of short sleep duration with hypertension incidence--a 6-year follow-up in the Korean genome and epidemiology study

BACKGROUND

Hypertension (HT) is caused by complex interactions between genetic and environmental factors. Despite evidence for an association between short sleep duration and the development of HT, genetic factors associated with this effect have not been defined. Here we prospectively investigated the incidence of HT in subjects with short sleep duration over a 6-year follow-up period, and identified associated genetic variants in a genome-wide association study.

METHODS AND RESULTS

Sleep duration was determined by questionnaire and 3 categories were established: <5h, 5-7h, and >7h. Genotyping was carried out using the Affymetrix Genome-Wide Human Single Nucleotide Polymorphism (SNP) Array 5.0. Of the 4,965 individuals included in our study, 1,071 (543 of 2,330 men, 528 of 2,635 women) developed HT. The cumulative incidence of HT during the 6-year study period was 21.6%. Sleep duration <5h was associated with an increased risk of incident HT only in premenopausal women (adjusted hazard ratio 2.43, 95% confidence interval 1.36-4.35). The SNPs of rs6691577, rs2226284 and rs12756253 were associated with this increased risk.

CONCLUSIONS

This prospective communitywide study showed that premenopausal women with short sleep duration had an increased risk of incident HT, and found associations with specific genomic markers.

Variability in home-measured blood pressure and heart rate: associations with self-reported insomnia and sleep duration

OBJECTIVE

Both self-reported sleep disorders and higher variability in home blood pressure (BP) and home heart rate (HR) have been associated with increased cardiovascular mortality. The objective of our study was to assess the associations of the variability in home-measured BP and HR with self-reported insomnia and sleep duration.

METHODS

We studied a representative sample of Finnish adult population with 1908 study participants aged 41-74 years. BP/HR measurements were performed on 7 consecutive days. The variability in home-measured BP/HR was defined as the standard deviation of morning - evening, day-by-day and first - second measurements. Self-reported insomnia and sleep duration questionnaires were used to classify participants with sleep disorders.

RESULTS

Results from Finn-home study show that morning - evening, day-by-day (morning and evening) and first - second home BP variability variables were significantly higher in participants with persistent insomnia than in those without insomnia. Morning - evening, day-by-day, morning day-by-day and first - second measurements of home HR variability variables were significantly higher in participants with persistent insomnia than in those without insomnia. Systolic morning - evening, day-by-day and morning day-by-day variables of home BP variability were significantly higher in long sleepers and systolic morning day-by-day, diastolic day-by-day and diastolic first - second measurement of home BP variability variables were higher in short sleepers than in the reference group. Insomnia combined with short sleep duration further increases home BP/HR variability.

CONCLUSION

As self-reported sleep disorders are associated with greater variability in home BP/HR and both have cardiovascular prognostic value, we encourage physicians to evaluate these easily obtainable measurements in clinical practice to help identify patients at risk.

Insomnia symptoms and cardiovascular disease among older American Indians: the Native Elder Care Study

Background. Cardiovascular disease (CVD) is the leading cause of death among American Indians. It is not known if symptoms of insomnia are associated with CVD in this population. Methods. We examined 449 American Indians aged ≥55 years from the Native Elder Care Study. The main outcome-of-interest was self-reported CVD. Results. Short sleep duration, daytime sleepiness, and difficulty falling asleep were positively associated with CVD after adjusting for demographic, lifestyle, and clinical risk factors. Compared with a sleep duration of 7 h, the multivariable odds ratio (OR) (95% confidence interval [CI]) of CVD among those with sleep duration ≤5 h was 2.89 (1.17–7.16). Similarly, the multivariable OR (95% CI) of CVD was 4.45 (1.85–10.72) and 2.60 (1.25–5.42) for daytime sleepiness >2 h and difficulty falling asleep often/always. Conclusion. Symptoms of insomnia including short sleep duration, daytime sleepiness, and difficulty falling asleep are independently associated with CVD in American Indians aged ≥55 years.

[Investigation of the factors that contribute to the onset of insomnia in hypertensive patients by using a post-marketing surveillance database]

Many factors contribute to the onset of insomnia. However, few studies have identified the factors related to the onset of insomnia in hypertensive patients. We conducted a pharmacoepidemiologic study to examine the incidence of insomnia in hypertensive patients by using a post-marketing surveillance database. The insomnia onset was defined as the time of first prescription of hypnotics. The insomnia incidence rate in hypertensive patients under antihypertensive therapy was 0.77/100 person-years. The median insomnia onset date was 5 weeks. The insomnia type in 50.2% of the patients was difficulty in initiating sleep. We assessed the factors contributing to insomnia by using a nested case-control design. We selected 10 time-matched controls for every case. The hypotensive effect induced by antihypertensive therapy on the case group was lesser than that on the control group (p<0.01). The odds ratios (ORs) were estimated using multivariate conditional logistic regression. The factors contributing to insomnia onset were α blockers (OR, 2.38; 95% confidence interval [CI], 1.14-4.98), β blockers (OR, 1.54; 95% CI, 0.99-2.39), and calcium channel blockers (OR, 0.62; 95% CI, 0.43-0.90) compared with angiotensin-converting enzyme inhibitors; female sex (OR, 1.76; 95% CI, 1.27-2.44); complication of gastric/duodenal disorders (OR, 2.35; 95% CI, 1.14-4.86) or musculoskeletal system/connective tissue disorders (OR, 2.43; 95% CI, 1.23-4.79); and concomitant antihypertensive therapy (OR, 0.44; 95% CI, 0.31-0.63). This study identified the potential factors that may help to predict insomnia onset in hypertensive patients under antihypertensive therapy.

Sleep duration and sleep quality in relation to 12-year cardiovascular disease incidence: the MORGEN study

STUDY OBJECTIVES

We studied sleep duration and sleep quality in relation to cardiovascular disease (CVD) incidence.

DESIGN/SETTING

Dutch population-based cohort study.

PARTICIPANTS

20,432 men and women aged 20-65 and with no history of CVD.

INTERVENTIONS

N/A.

MEASUREMENTS

Sleep duration and sleep quality were assessed by a self-administered questionnaire. Morbidity data, vital status, and causes of death were obtained through linkage with several national registries. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated using Cox proportional hazards models.

RESULTS

During 10-15 years of follow-up, 1,486 CVD and 1,148 coronary heart disease (CHD) events occurred. Short sleepers (≤ 6 h) had a 15% higher risk of total CVD (HR: 1.15; 95%CI: 1.00-1.32) and a 23% higher risk of CHD (HR: 1.23 [1.04-1.45]) compared to normal sleepers (7 h) after adjustment for all confounders. Additional adjustment for intermediate biological risk factors attenuated these relative risks to 1.11 (0.97-1.27) for total CVD and to 1.19 (1.00-1.40) for CHD. Short sleepers with poor sleep quality had a 63% higher risk of CVD (HR: 1.63 [1.21-2.19]) and a 79% higher risk of CHD incidence (HR: 1.79 [1.24-2.58]) compared to normal sleepers with good sleep quality, after adjustments for all confounders. We observed no associations between long sleep duration (≥ 9 h) and CVD or CHD incidence.

CONCLUSIONS

Short sleepers, especially those with poor sleep quality, have an increased risk of total CVD and CHD incidence. Future investigations should not only focus on sleep duration, but should also take sleep quality into account.

Sleep loss due to worry and future risk of cardiovascular disease and all-cause mortality: the Scottish Health Survey

BACKGROUND

The association between specific sleeping disorders and risk of cardiovascular disease (CVD) is unclear. We assessed the association between sleep loss due to worry and future risk of CVD and death in a representative sample of community dwelling adults.

METHODS

A cohort of 11,905 adults (aged 53.4 ± 12.2 years, 42.2% male) without known history of CVD were drawn from the Scottish Health Surveys. Self-reported sleep disturbance was measured using a single item from the General Health Questionnaire. Incident CVD events (comprising CVD death, nonfatal myocardial infarction, coronary surgical procedures, stroke, and heart failure) over 8-year follow up were ascertained by a linkage to national registers; a total of 1448 CVD events and 1249 all-cause deaths were recorded.

RESULTS

15.6% of the sample reported 'rather more' or 'much more than usual' sleep loss due to worry over the prior 4 weeks. Sleep loss due to worry (much more than usual) was associated with elevated risk of CVD [age- and sex-adjusted hazard ratio (HR) 1.74, 95% confidence interval (CI) 1.35-2.25] and all-cause mortality (age- and sex-adjusted HR 2.02, 95% CI 1.57-2.61). Adjustment for a range of psychosocial, behavioural, and clinical risk factors partly attenuated the association, and in particular health behaviours (smoking, alcohol, physical inactivity) accounted for approximately 40% of the sleep-CVD relation.

CONCLUSION

Sleep loss due to worry was associated with a greater risk of CVD and all-cause mortality, but the association can be largely explained by intermediate risk factors such as health behaviours.

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.

Clinical outcome after acute ischaemic stroke: the influence of restless legs syndrome

BACKGROUND AND PURPOSE

the objective was to evaluate the presence of Restless Legs Syndrome (RLS) in acute stroke, its association with sleep disturbances and clinical outcome during long-term follow-up.

METHODS

this was a longitudinal study (N = 96, 59 men, mean age 64.0 ± 8.9) of cases with acute ischaemic stroke. Patients were asked about the occurrence of RLS symptoms before the cerebrovascular event. RLS was diagnosed using the criteria established by the International RLS Study Group. Stroke outcome was estimated by the Barthel Index and the modified Rankin Scale. Daytime somnolence (Epworth Sleepiness Scale -ESS > 10), poor sleep quality (Pittsburgh Sleep Quality Index -PSQI > 5) and risk of obstructive sleep apnea (OSA) (Berlin questionnaire) were evaluated.

RESULTS

twelve patients (12.5%) met the diagnostic criteria for RLS. All cases had symptoms of RLS before stroke. However, none of the cases had a previous medical diagnosis of RLS or were on use of specific medication. In only one case, a family history of RLS was found. In all patients, RLS symptoms started after the age of 40 (mean age 64 ± 6.7). Daytime sleepiness (44.8%) and poor quality sleep (62.8%) were present. Patients with RLS (12.5%) presented greater neck circumference (P = 0.04) and worse sleep quality (P = 0.007). Risk of OSA (56.2%) was associated with hypertension [OR = 0.12; CI=0.03-0.42]. Stroke outcome was significantly worse at three and 12 months (ancova, P < 0.005) in patients with RLS, remaining after adjustment for diabetes and body mass index (P < 0.05).

CONCLUSIONS

patients with acute stroke and RLS have worse clinical outcome, at three and 12 months of follow-up.

Poor sleep and cardiovascular function in children

We investigated whether sleep quantity and quality were related to 24-hour ambulatory blood pressure and cardiovascular reactivity in children. We studied term-born, healthy 8.0-year olds (SD: 1.4 years) without sleep-disordered breathing (231 and 265 children provided valid data for analyses of ambulatory blood pressure and cardiovascular reactivity, respectively). Sleep was registered with an actigraph for 6 nights on average (SD: 1.2; range: 3 to 13 nights). Ambulatory blood pressure was measured for 24-hours (41% nonschool days) with an oscillometric device. The children underwent the Trier Social Stress Test for Children, during which blood pressure, electrocardiography, and thoracic impedance were recorded and processed offline to give measures of cardiovascular and autonomic function. Neither quantity nor quality of sleep was related to 24-hour ambulatory blood pressure or cardiovascular reactivity after accounting for major covariates (sex, age, height, body mass index, and parental education). Although lower sympathetic nervous system activation and higher cardiac activation under stress were found in the group of children who slept for short duration when they were compared with the average sleep duration group, these associations were not significant after correction for multiple testing and were not seen in linear regression models of the effects of sleep duration. These findings do not support the mainstream of epidemiological findings, derived from samples more heterogeneous in age, sociodemographic characteristics, and health, suggesting that poor sleep is associated with an unhealthy cardiovascular phenotype.

Risk factors for cardiovascular disease in the very elderly: results of a cohort study in a city in southern Brazil

BACKGROUND

Risk factors for cardiovascular mortality have barely been investigated in very elderly persons and there may be differences compared with younger individuals.

METHODS

This is a cohort study of all inhabitants over 80 years of age in the city of Veranópolis, Brazil. The association of demographic, anthropometric, physical, and medical characteristics with mortality by any cause and by cardiovascular disease (CVD) was investigated by means of Cox regression models.

RESULTS

The mean age of the participants was 83.6 ± 3.3 years. Vital status and cause of death was ascertained in 96.9% of the participants after a mean follow-up of 8.7 ± 3.8 years. Systolic and diastolic blood pressure showed a U-shape relationship with cardiovascular and total mortality. Blood pressure lower than 140/90 mmHg was associated with a higher risk for cardiovascular mortality (HR 4.76, 95% CI 1.56-14.28, p = 0.006). Duration of sleep was inversely associated with the risk of cardiovascular death (HR 0.83, 95% CI 0.73-0.95, p = 0.007), while apoA-I was inversely associated only with the risk of all-cause mortality (HR 0.99, 95% CI 0.98-1.00, p = 0.041). Anthropometric indexes, smoking, cholesterol, LDL-cholesterol, HDL-cholesterol, and other traditional risk factors were not associated with cardiovascular mortality.

CONCLUSION

Many traditional risk factors are not associated with cardiovascular mortality in the very elderly. Longer sleep duration is associated with lower cardiovascular mortality of very elderly individuals, while low blood pressure identifies very elderly individuals at higher risk of dying from cardiovascular causes.

Relationship between sleep duration and clustering of metabolic syndrome diagnostic components

OBJECTIVE

To examine the relation between sleep duration and metabolic syndrome (MetS).

METHODS

We examined the baseline data from 4356 healthy workers (3556 men and 800 women) aged 19-69 years. The physical activity of each participant was classified according to the International Physical Activity Questionnaire (IPAQ). We defined four components of MetS diagnostic components in this study as follows: 1) high blood pressure (BP) systolic BP [SBP] ≥ 130 mmHg, or diastolic BP [DBP] ≥ 85 mmHg, or on medication; 2) dyslipidemia (high-density lipoprotein-cholesterol concentration <40 mg/dL, or triglycerides concentration ≥150 mg/dL, or on medication; 3) impaired glucose tolerance (fasting blood sugar concentration ≥ 110 mg/dL, or if less than 8 hours after meals ≥ 140 mg/dL), or on medication; and 4) overweight (body mass index [BMI] ≥ 25 kg/m(2)), or obesity (BMI ≥ 30 kg/m(2)). There were 680 participants in the group, with sleep duration <6 hours (15.6%).

RESULTS

Those who had 0-4 MetS diagnostic components, including overweight, accounted for 2159, 1222, 674, 255, and 46 participants, respectively, in the Poisson distribution. Poisson regression analysis revealed that independent factors that contributed to the number of MetS diagnostic components were being male (regression coefficient b = 0.752, P < 0.001), age (b = 0.026, P < 0.001), IPAQ classification (b = -0.238, P = 0.034), and alcohol intake (mL/day) (b = 0.018, P < 0.001). Short sleep duration (<6 hours) was also related to the number of MetS (b = 0.162, P < 0.001). The results of analyses with obesity component showed a similar association.

CONCLUSION

Short sleep duration was positively associated with the number of MetS diagnostic components independent of other lifestyle habits.

Hypersomnolence and sleep disorders in a rheumatic disease patient population

OBJECTIVES

There is increasing awareness of the importance of sleep in health maintenance. Our primary objective was to evaluate prevalence of excess daytime sleepiness in a rheumatic disease patient population. Secondary objectives included evaluation of prevalence of abnormal sleep quality and primary sleep disorders.

METHODS

Consecutive Rheumatology clinic patients were invited to participate in a self-administered questionnaire study. Included were measures for pain, fatigue, and global functioning, modified Health Assessment Questionnaire, Epworth Sleepiness Score (ESS), Pittsburgh Sleep Quality Index (PSQI), Berlin Score, diagnostic criteria for restless legs syndrome (RLS), Centre for Epidemiologic Studies Depression score (CES-D), stress scores, and the short form-36 quality of life instrument.

RESULTS

Of 507 consecutive patients invited to participate, 423 agreed. Mean age was 52.1 years; 26% were male. Prevalence of excessive sleepiness (ESS >10) was 25.7%, abnormal sleep quality (PSQI >5) was 67.3%, high risk for obstructive sleep apnea Berlin scores were present in 35.2% and 24% of participants met criteria for RLS. Significantly worse pain, fatigue, global function, short form-36 summary scores, modified Health Assessment Questionnaire, depression, and stress scores were present in patients with higher ESS and PSQI scores. No significant differences in sleep assessment scores were observed between specific rheumatic disease groups.

CONCLUSIONS

Our findings suggest a high prevalence of unrecognized hypersomnolence, poor sleep quality, and primary sleep disorders in rheumatology patients. We suggest evaluation of sleep health be incorporated into standard clinical assessments of all rheumatology patients. We would recommend this evaluation include the ESS and the criteria for RLS.

Effects of sleep restriction on adiponectin levels in healthy men and women

OBJECTIVE

Population studies have consistently found that shorter sleep durations are associated with obesity and cardiovascular disease, particularly among women. Adiponectin is an adipocyte-derived, anti-inflammatory hormone that is related to cardiovascular disease risk. We hypothesized that sleep restriction would reduce adiponectin levels in healthy young adults.

METHODS

74 healthy adults (57% men, 63% African American, mean age 29.9years) completed 2 nights of baseline sleep at 10h time in bed (TIB) per night followed by 5 nights of sleep restricted to 4h TIB per night. An additional 8 participants were randomized to a control group that received 10h TIB per night throughout the study. Plasma adiponectin levels were measured following the second night of baseline sleep and the fifth night of sleep restriction or control sleep.

RESULTS

Sleep restriction resulted in a decrease in plasma adiponectin levels among Caucasian women (Z=-2.19, p=0.028), but an increase among African American women (Z=-2.73, p=0.006). No significant effects of sleep restriction on adiponectin levels were found among men. A 2×2 between-group analysis of covariance on adiponectin change scores controlling for BMI confirmed significant interactions between sleep restriction and race/ethnicity [F(1,66)=13.73, p<0.001], as well as among sleep restriction, race/ethnicity and sex [F(1,66)=4.27, p=0.043)].

CONCLUSIONS

Inflammatory responses to sleep loss appear to be moderated by sex and race/ethnicity; observed decreases in adiponectin following sleep restriction may be one avenue by which reduced sleep duration promotes cardiovascular risk in Caucasian women.

Age-dependent association between sleep duration and hypertension in the adult Korean population

BACKGROUND

In Western countries, sleep deprivation has been reported to elevate blood pressure. Here, we examined whether this association is true also for an Asian population.

METHODS

The study sample comprised 5,393 Korean adults aged 19-99 years who had participated in the 2005 Korean National Health and Nutrition Examination Survey. Hypertension was defined as a systolic blood pressure (SBP) ≥140 mm Hg or a diastolic blood pressure (DBP) ≥90 mm Hg, or regular use of antihypertensive medication.

RESULTS

Among the participants, 1,345 subjects (24.9%) displayed hypertension. The median sleep duration was 7 h/day. In the young and middle-aged adults aged <65 years, the unadjusted odds ratio (OR) for hypertension was 1.5-fold greater in those with a sleep duration of ≤5 h (OR 1.52; 95% confidence interval (CI) 1.19, 1.94) as compared to those who slept 7 h. This trend did not significantly change after adjustments for putative risk factors for hypertension such as gender, obesity, smoking status, alcohol consumption, physical activity, depressive symptom, diabetes mellitus, and stroke (OR 1.31; 95% CI 1.01, 1.71). However, in the older adults aged ≥65 years, no association was found between sleep duration and the risk of hypertension. Long sleep duration (≥8 h) was not associated with hypertension in either the younger or older adults in this study.

CONCLUSION

Short sleep duration (≤5 h) is independently associated with hypertension in young and middle-aged Korean adults.

Sleeping with one eye open: marital abuse as an antecedent of poor sleep

In a diverse community sample of 241 married couples, we examined received psychological abuse (PA) as a longitudinal predictor of men's and women's sleep. Participants reported on marital functioning and mental health during three assessments (T1, T2, T3) and sleep problems during two assessments (T2, T3), with 1-year lags between waves. Growth curve analyses revealed that for both spouses, higher initial levels of PA and increases in PA over time predicted greater sleep disturbances at T3. For husbands and wives, anxiety and depression mediated some of the associations between PA and sleep problems. For wives, moderation effects highlighted the importance of violence, anxiety, and depression in exacerbating sleep problems associated with PA. Results build on and contribute significantly to the scant literature implicating the importance of the marital relationship for sleep and suggest that simultaneous consideration of intrapersonal and interpersonal variables is critical when explicating sleep disruptions.

Sleep duration and cardiovascular disease: results from the National Health Interview Survey

BACKGROUND

Previous studies have shown that both short and long sleep durations are related to increased likelihood of diabetes and hypertension. However, the relation between sleep duration and cardiovascular disease (CVD) is not clear. We examined the hypothesis that compared with sleep duration of 7 hours, shorter and longer sleep durations are independently related to CVD.

METHODS

We conducted a cross-sectional study of 30,397 National Health Interview Survey 2005 participants > or = 18 years of age (57.1% women). Sleep duration was categorized as < or = 5 hours, 6 hours, 7 hours, 8 hours, and > or = 9 hours. The main outcome of interest was the presence of any CVD (n = 2146), including myocardial infarction, angina, and stroke.

RESULTS

We found both short and long sleep durations to be independently associated with CVD, independent of age, sex, race-ethnicity, smoking, alcohol intake, body mass index, physical activity, diabetes mellitus, hypertension, and depression. Compared with a sleep duration of 7 h (referent), the multivariate odds ratio (95% confidence interval) of CVD was 2.20 (1.78, 2.71), 1.33 (1.13, 1.57), 1.23 (1.06, 1.41), and 1.57 (1.31, 1.89) for sleep duration < or = 5 h, 6 h, 8 h, and > or = 9 h. This association persisted in subgroup analyses by gender, race-ethnicity, and body mass index categories. Also, similar associations were observed when we examined myocardial infarction and stroke separately.

CONCLUSION

Compared with sleep duration of 7 h, there was a positive association between both shorter and longer sleep durations and CVD in a representative sample of US adults. These results suggest that sleep duration may be an important marker of CVD.

Sleeping during the day: effects on the 24-h patterns of IGF-binding protein 1, insulin, glucose, cortisol, and growth hormone

BACKGROUND

Disturbed sleep is a major risk factor for metabolic disturbances, including type 2 diabetes, but the involved mechanisms are still poorly understood. We investigated how an acute shift of sleep to the daytime affected IGF-binding protein 1 (IGFBP1), which is a risk factor for diabetes.

METHODS

Seven healthy men (age, 22-32 years) participated in a night sleep condition (sleep 2300-0700 h) and a day sleep condition (0700-1500 h) with hourly blood samples taken for 25 h (starting at 1900 h) and isocaloric meals every 4th hour awake. The blood samples were analyzed for IGFBP1, insulin, GH, glucose, and cortisol.

RESULT

The acute shift of sleep and meal timing (to 8 h) shifted the 24-h patterns of IGFBP1, glucose, insulin, and GH to a similar degree. However, the day sleep condition also resulted in elevated levels of IGFBP1 (area under curve (AUC)+22%, P<0.05), and reduced glucose levels (AUC-7%, P<0.05) compared with nocturnal sleep. Sleeping during the day resulted in elevated cortisol levels during early sleep and reduced levels in late sleep, but also in increased levels the subsequent evening (P's<0.05).

CONCLUSION

Sleep-fasting seems to be the primary cause for the elevation of IGFBP1, irrespective of sleep timing. However, sleeping during the day resulted in higher levels of IGFBP1 than nocturnal sleep, suggesting altered metabolism among healthy individuals, which may have implications for other groups with altered sleep/eating habits such as shift workers. Moreover, sleep and meal times should be accounted for while interpreting IGFBP1 samples.

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.

Prevalence of self-reported clinically diagnosed sleep apnea according to obesity status in men and women: National Health and Nutrition Examination Survey, 2005-2006

OBJECTIVE

To estimate the prevalence of self-reported clinically diagnosed sleep apnea (diagnosed sleep apnea) according to body mass index (BMI, measure of total obesity) and waist circumference (measure of abdominal obesity) in US adults.

METHODS

Data from a representative sample of 4309 US adults in the National Health and Nutrition Examination Surveys 2005-2006 were analyzed. Log-linear regression analyses with a robust variance estimator were performed to estimate the prevalence ratios (PR) and 95% confidence intervals (CIs).

RESULTS

The overall crude and age-adjusted prevalence estimates of diagnosed sleep apnea were 4.7% (95% CI=4.0%-5.5%) and 4.5% (95% CI=3.9%-5.2%) in adults. Age-adjusted prevalence in men (6.1%, 95% CI=5.0%-7.3%) was higher than that in women (3.1%, 95% CI=2.1%-4.0%; P<0.01). Age-adjusted prevalence was higher for persons with total obesity (i.e., BMI > or = 30 kg/m(2)) (12.1% vs. 3.0% in men, P<0.01; 7.0% vs. 0.7% in women, P<0.01) or abdominal obesity (10.9% vs. 1.9% in men, P<0.01; 4.6% vs. 0.6% in women, P<0.01) than that for those without total obesity (BMI <30 kg/m(2)) or without abdominal obesity.

CONCLUSIONS

These results from a nationally representative sample suggest that diagnosed sleep apnea is highly prevalent among adults with obesity in the general population, especially among men.

Mortality associated with short sleep duration: The evidence, the possible mechanisms, and the future

This review of the scientific literature examines the widely observed relationship between sleep duration and mortality. As early as 1964, data have shown that 7-h sleepers experience the lowest risks for all-cause mortality, whereas those at the shortest and longest sleep durations have significantly higher mortality risks. Numerous follow-up studies from around the world (e.g., Japan, Israel, Sweden, Finland, the United Kingdom) show similar relationships. We discuss possible mechanisms, including cardiovascular disease, obesity, physiologic stress, immunity, and socioeconomic status. We put forth a social-ecological framework to explore five possible pathways for the relationship between sleep duration and mortality, and we conclude with a four-point agenda for future research.

Controlling evening BP as well as morning BP is important in hypertensive patients with prediabetes/diabetes: the JMS-1 study

BACKGROUND

The significance of home blood pressure (BP) measurement in type 2 diabetes (T2DM) has not been well investigated. We aimed to test the hypotheses that home BP is more closely associated with target-organ damage than clinic BP, and that the presence of prediabetes/T2DM enhances the impact of home BP measurement.

METHODS

We studied 551 hypertensives (99 diabetics and 452 nondiabetics) whose self-measured systolic BP (SBP) was >135 mm Hg while on medication. The subjects were followed for 6 months after allocation to either a control group or an active treatment group. The changes in clinic BP and home BP were analyzed in relation to the changes in the spot urine albumin-creatinine ratio (UAR).

RESULTS

The extent of clinic and home BP reduction was similar between the diabetic and nondiabetic groups. The change in UAR in nondiabetics was significantly associated with the extent of SBP reduction in the clinic (r = 0.19), morning (r = 0.33), and evening (r = 0.22, all P < 0.01). In contrast, in the diabetic group, the change in UAR was significantly associated with the changes in morning SBP (r = 0.23, P = 0.02) and evening SBP (r = 0.39, P < 0.001), but not with clinic BP. The correlation with evening SBP in the diabetic group tended to be stronger than the nondiabetic group.

CONCLUSIONS

In hypertensives with prediabetes/T2DM, changes in home BP were better than changes in clinic BP to predict changes in UAR. In particular, this suggests the hypothesis that aggressive control of evening home BP might be equally or more important to morning BP in hypertensives with prediabetes/T2DM.

Molecular time: an often overlooked dimension to cardiovascular disease

Diurnal rhythms influence cardiovascular physiology such as heart rate and blood pressure and the incidence of adverse cardiac events such as heart attack and stroke. For example, shift workers and patients with sleep disturbances, such as obstructive sleep apnea, have an increased risk of heart attack, stroke, and sudden death. Diurnal variation is also evident at the molecular level, as gene expression in the heart and blood vessels is remarkably different in the day as compared to the night. Much of the evidence presented here indicates that growth and renewal (structural remodeling) are highly dependent on processes that occur during the subjective night. Myocardial metabolism is also dynamic with substrate preference also differing day from night. The risk/benefit ratio of some therapeutic strategies and the appearance of biomarkers also vary across the 24-hour diurnal cycle. Synchrony between external and internal diurnal rhythms and harmony among the molecular rhythms within the cell is essential for normal organ biology. Cell physiology is 4 dimensional; the substrate and enzymatic components of a given metabolic pathway must be present not only in the right compartmental space within the cell but also at the right time. As a corollary, we show disrupting this integral relationship has devastating effects on cardiovascular, renal and possibly other organ systems. Harmony between our biology and our environment is vital to good health.

Do restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) play a role in nocturnal hypertension and increased cardiovascular risk of renally impaired patients?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease.

Relationship between self-reported sleep duration and changes in circadian blood pressure

BACKGROUND

Abnormalities in sleep duration and circadian blood pressure (BP) rhythm are both independently associated with increased risk of death and cardiovascular disease. The relationship, however, between these two entities remains unclear. This study was undertaken to determine whether abnormal sleep duration is associated with nondipping status and elevated morning surge.

METHODS

In a cross-sectional study, we assessed the relationship between self-reported sleep duration and circadian BP profiles from 24-h ambulatory BP monitoring (ABPM) in 108 normotensive and 417 hypertensive subjects, independent of relevant sociodemographic, anthropometric, and medical factors.

RESULTS

On average, subjects reported sleeping 6.5 +/- 1.7 h with 18.5% sleeping < or =5 h and 7.6%, > or =9 h. There were 199 (37.9%) nondippers in our cohort and the mean morning surge was 18.7 +/- 1.7 mm Hg. The adjusted odds ratio for nondipping (<10% nocturnal systolic BP fall) associated with a 1-h decrement in sleep duration was 1.12 (P = 0.04) and with age per 5-year increment, 1.15 (P = 0.0003). The adjusted odds ratio for an elevated morning surge (> or =18.0 mm Hg) associated with a 1-h increment in sleep duration was 1.13 (P = 0.02).

CONCLUSIONS

Our study indicates that a sleep deficit is associated with nondipping and a decreased morning surge, whereas a sleep surfeit is associated with less nondipping and an increased morning surge. These findings provide a possible link for the heightened risk of cardiovascular disease associated with disturbances in circadian BP rhythm and the extremes of sleep quantity.

Do restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) play a role in nocturnal hypertension and increased cardiovascular risk of renally impaired patients?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease.