Blood pressure and heart rate during continuous experimental sleep fragmentation in healthy adults

Behavioral Sleep Interventions and Cardiovascular Risk Factors: Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND/OBJECTIVES

Chronic sleep disturbance has been consistently associated with cardiovascular disease. We sought to determine whether behavioral interventions to improve sleep have been associated with improvements in 4 common cardiovascular disease risk factors: hypertension, diabetes mellitus (DM), obesity, and smoking.

METHODS

Randomized controlled trials evaluating the prospective effect of behavioral sleep interventions on (a) blood pressure in participants with hypertension/prehypertension, (b) glycemic control in participants with DM/pre-DM, (c) anthropometrics in participants who were overweight/obese, and (d) smoking status in smokers were eligible. Where feasible, we undertook random-effects meta-analyses of standardized mean differences in cardiovascular disease risk factor change.

RESULTS

Overall, 3 trials met the inclusion criteria for blood pressure, 4 for glycemic control, 9 for overweight/obesity, and 2 for smoking. On meta-analysis, interventions with sleep as the sole behavioral target were associated with a significant reduction in hemoglobin A1c% (-0.84; 95% confidence interval [CI], -1.34 to -0.34), but not a significant reduction in systolic blood pressure (-0.18; 95% CI, -0.55 to 0.20) versus controls. In addition, any interventions with sleep as a behavioral target were associated with significant reductions in hemoglobin A1c% (-0.71; 95% CI, -1.01 to -0.42) and weight (-0.78; 95% CI, -1.11 to -0.45), but not systolic blood pressure (-0.72; 95% CI, -1.82 to 0.37). Trials evaluating smoking status were not amenable to meta-analysis.

CONCLUSION

Behavioral interventions to improve sleep were associated with improved glycemic control in patients with DM. It is also possible that these interventions improve weight in individuals who were overweight/obese. A low number of trials and small sample sizes indicate that further large, well-designed randomized controlled trials of interventions are warranted.

Sleep Deprivation and Heart Rate Variability in Healthy Volunteers: Effects of REM and SWS Sleep Deprivation

Objective

Using PSG-guided acute selective REM/SWS sleep deprivation in volunteers, this study examined the effects of sleep deprivation on the cardiovascular and autonomic nervous systems, as well as the relationship between cardiac neuromodulation homeostasis and cardiovascular disease.

Methods

An experiment was conducted using 30 healthy volunteers (male : female = 1 : 1, aged 26.33 ± 4.5 years) divided into groups for sleep deprivation of SWS and REM sleep, and then, each group was crossed over for normal sleep (2 days) and repeated sleep deprivation (1 day, 3 times). During the study period, PSG and ELECTRO ECG monitoring were conducted, and five-minute frequency domain parameters and blood pressure values were measured before and after sleep deprivation.

Results

Changes in VLF, LFnu, LF/HF, HF, and HFnu after SWS sleep deprivation were statistically significant (P < 0.05), but not LF (P = 0.063). Changes in VLF, LF, HF, LF/HF, LFnu, and HFnu after REM sleep deprivation were not statistically significant (P > 0.05).

Conclusions

An increase in sympathetic nerve activity results from sleep deprivation and sudden awakening from SWS sleep is associated with a greater risk of cardiovascular disease.

Effects of sleep fragmentation and partial sleep restriction on heart rate variability during night

We developed a cross-over study design with two interventions in randomized order to compare the effects of sleep fragmentation and partial sleep restriction on cardiac autonomic tone. Twenty male subjects (40.6 ± 7.5 years old) underwent overnight polysomnography during 2 weeks, each week containing one undisturbed baseline night, one intervention night (either sleep restriction with 5 h of sleep or sleep fragmentation with awakening every hour) and two undisturbed recovery nights. Parameters of heart rate variability (HRV) were used to assess cardiac autonomic modulation during the nights. Sleep restriction showed significant higher heart rate (p = 0.018) and lower HRV-pNN50 (p = 0.012) during sleep stage N1 and lower HRV-SDNN (p = 0.009) during wakefulness compared to the respective baseline. For HR and SDNN there were recovery effects. There was no significant difference comparing fragmentation night and its baseline. Comparing both intervention nights, sleep restriction had lower HRV high frequency (HF) components in stage N1 (p = 0.018) and stage N2 (p = 0.012), lower HRV low frequency (LF) (p = 0.007) regarding the entire night and lower SDNN (p = 0.033) during WASO during sleep. Sleep restriction increases sympathetic tone and decreases vagal tone during night causing increased autonomic stress, while fragmented sleep does not affect cardiac autonomic parameters in our sample.

Effect of selective sleep deprivation on heart rate variability in post-90s healthy volunteers

The 5-minute frequency domain method was used to examine the effects of polysomnography (PSG)-guided acute selective sleep deprivation (REM/SWS) on the cardiovascular autonomic nervous system, heart rate, and rhythm in healthy volunteers to understand the relationship between cardiac neuro regulatory homeostasis and cardiovascular system diseases in healthy subjects. The study included 30 healthy volunteers selected through the randomized-controlled method, randomly divided into REM sleep deprivation and SWS sleep deprivation groups. PSG analyses and dynamic electrocardiogram monitoring were done at night, during slow wave sleep or REM sleep. An all-night sleep paradigm, without any interruptions, was tested 3 times for comparison. The frequency domain parameter method was further used to monitor the volunteers 5 min before and after a period of sleep deprivation. According to the characteristics of the all-night sleep scatter plot, healthy volunteers were divided into abnormal and normal scatter plot groups. When compared with the period before sleep deprivation, high frequency (HF) and normalized high-frequency component (HFnu) were found to be decreased. Normalized low-frequency component (LFnu) increased in the abnormal scatter plot group after sleep deprivation, and this difference was statistically significant (P < 0.05). The scatter plot also showed that very low frequency (VLF) increased only in the normal group after deprivation and this difference, as well, was statistically significant (P < 0.05). The increase in diastolic blood pressure in the abnormal group was statistically significant (P < 0.05), but the change in blood pressure in the normal group was not statistically significant (P > 0.05). There are 62.5% of the patients and 20% of the employees that were observed to have abnormal whole-night sleep patterns during the uninterrupted whole-night sleep regime. Patients with atrial or ventricular premature beats (more than 0.1%), and those with ST-t changes during sleep, were all ascertained as abnormal. We concluded that some healthy people could face unstable autonomic nervous functioning related to their long-term tension, anxiety, time urgency, hostility, and other chronic stress states. In the face of acute sleep deprivation selectivity, mild stress based excitability of the vagus nerve is reduced, which diminishes the protective function, making them susceptible to conditions such as premature ventricular arrhythmia.

Third-Trimester Maternal Dietary Patterns Are Associated with Sleep Health among Adolescent Offspring in a Mexico City Cohort

BACKGROUND

Maternal diet during gestation has been linked to infant sleep; whether associations persist through adolescence is unknown.

OBJECTIVES

We explored associations between trimester-specific maternal diet patterns and measures of sleep health among adolescent offspring in a Mexico City birth cohort.

METHODS

Data from 310 mother-adolescent dyads were analyzed. Maternal diet patterns were identified by principal component analysis derived from FFQs collected during each trimester of pregnancy. Sleep duration, midpoint, and fragmentation were obtained from 7-d actigraphy data when adolescents were between 12 and 20 y old. Unstratified and sex-stratified association analyses were conducted using linear regression models, adjusted for potential confounders.

RESULTS

Mean ± SD age of offspring was 15.1 ± 1.9 y, and 52.3% of the sample was female. Three diet patterns were identified during each trimester of pregnancy: the Prudent Diet (PD), high in lean proteins and vegetables; the Transitioning Mexican Diet (TMD), high in westernized foods; and the High Meat & Fat Diet (HMFD), high in meats and fat products. Mean ± SD sleep duration was 8.5 ± 1.5 h/night. Most associations were found in the third trimester. Specifically, PD maternal adherence was associated with shorter sleep duration among offspring (-0.57 h; 95% CI: -0.98, -0.16 h, in the highest tertile compared with the lowest) and earlier sleep midpoint among females (-0.77 h; 95% CI: -1.3, -0.26 h). Adherence to the HMFD and TMD was nonlinearly associated with less fragmented sleep, with the latter only evident among females.

CONCLUSIONS

Findings indicate that maternal dietary patterns, especially during the third trimester of pregnancy, may have long-term impacts on offspring sleep.

Sleep Deficiency: Epidemiology and Effects

Adequate sleep is an important pillar of physical and mental health. Sleep deficiency, resulting from short sleep or suboptimal sleep quality, is highly prevalent in modern society. Occupation, social demands, psychiatric disorders, physical disorders, and sleep disorders are some of the contributing factors to sleep deficiency. Some populations are at increased risk of sleep deficiency based on ethnicity, age, marital status, sex, and hospitalization. Sleep deficiency influences cognition, alertness, mood, behavior, diabetes, cardiovascular health, renal function, immune system, and respiratory physiology. This review summarizes the epidemiology and effects of sleep deficiency.

Proton Pump Inhibitor "Lansoprazole" Inhibits Locus Coeruleus's Neuronal Activity and Increases Rapid Eye Movement Sleep

Alteration of the bodily CO₂ concentration and proton pump activity affects the sleep architecture. The brainstem locus coeruleus (LC) area plays an essential role in rapid eye movement (REM) sleep generation and chemoregulation. Previously, we reported that lansoprazole injections (intraperitoneal) increased REM sleep in the rats. However, it is not known if proton pumps in the LC influence REM sleep. Here, we studied the effects of lansoprazole in the LC on the neuronal activity and REM sleep expression. Male Wistar rats (250-300 g) were surgically prepared for sleep recording and drug microinjections into the LC. We determined the localization of proton pumps and expression levels of cFOS in the LC neurons immunohistochemically. Sleep-wake was recorded before and after the microinjections of drugs/vehicles. Our results demonstrate (i) the presence of proton pumps in the LC neurons, (ii) that the microinjection of lansoprazole into the LC reduced the number of cFOS^+ve-TH^+ve double-labeled neurons in the LC by 52.6% (p < 0.001) compared to the vehicle and (iii) that low and high doses of lansoprazole significantly increased REM sleep by 32% (p < 0.001) and 60% (p < 0.001), respectively, compared to the vehicle. Our results suggest that the proton pumps modulate the LC's noradrenergic (NE-ergic) neuronal activity and REM sleep. The increased amount of REM sleep can be attributed to the inhibition of the LC NE-ergic activity. Further, the REM sleep amount increased after the lansoprazole microinjections into the LC with a significant increase in the REM sleep episode numbers. Overall, our results suggest that proton pumps in the LC may be involved in REM sleep generation.

Digital sleep measures and white matter health in the Framingham Heart Study

AIM

Impaired sleep quality and sleep oxygenation are common sleep pathologies. This study assessed the impact of these abnormalities on white matter (WM) integrity in an epidemiological cohort.

METHODS

The target population was the Framingham Heart Study Generation-2/Omni-1 Cohorts. Magnetic resonance imaging (diffusion tensor imaging) was used to assess WM integrity. Wearable digital devices were used to assess sleep quality: the (M1-SleepImage™ system) and the Nonin WristOx for nocturnal oxygenation. The M1 device collects trunk actigraphy and the electrocardiogram (ECG); sleep stability indices were computed using cardiopulmonary coupling using the ECG. Two nights of recording were averaged.

RESULTS

Stable sleep was positively associated with WM health. Actigraphic periods of wake during the sleep period were associated with increased mean diffusivity. One marker of sleep fragmentation which covaries with respiratory chemoreflex activation was associated with reduced fractional anisotropy and increased mean diffusivity. Both oxygen desaturation index and oxygen saturation time under 90% were associated with pathological directions of diffusion tensor imaging signals. Gender differences were noted across most variables, with female sex showing the larger and significant impact.

CONCLUSIONS

Sleep quality assessed by a novel digital analysis and sleep hypoxia was associated with WM injury, especially in women.

Effects of ambulatory blood pressure monitoring on sleep in healthy, normotensive men and women

OBJECTIVES

To determine the effect of ambulatory blood pressure monitoring (ABPM) on sleep quality among healthy adults and to explore possible effect modification by demographics.

METHODS

We examined data from 192 relatively healthy young (median age: 31; 33% men, 18% with clinic BP >130/80 mmHg) participants in an observational study of sleep and arterial stiffness. Demographic/health questionnaires were completed. A wrist-based accelerometer assessed sleep for seven nights, and sleep duration, wakefulness after sleep onset (WASO), fragmentation (physical restlessness), midpoint, and efficiency were estimated. ABPM was conducted for one 36-h period, including one actigraphy night.

RESULTS

Within-subject comparisons indicated that WASO and fragmentation were higher, midpoint was later, and efficiency was lower on the ABPM night (Ps < 0.001-0.038). Neither age nor sex moderated these associations. Among older adults, a later midpoint and worse fragmentation were observed with ABPM (Ps = 0.002-0.010). There was also a main effect of sex: men demonstrated shorter sleep duration, greater WASO and fragmentation, and less efficiency than women (Ps = 0.002-0.046). With ABPM, women had worse fragmentation and a later midpoint (Ps = 0.002-0.049); for men, WASO and fragmentation were worse (Ps = 0.003-0.023). Importantly, this study does not address whether the effect of wearing ABPM on sleep in turn affects BP during sleep.

CONCLUSIONS

ABPM appears to modestly disturb actigraphy-assessed sleep among healthy adults. Researchers and clinicians should consider the downstream effects of performing ABPM and whether these effects are more pronounced in those who typically experience sleep disturbance.

Proteomic Profiling Reveals the Molecular Changes of Insomnia Patients

Background

Insomnia is an economic burden and public health problem. This study is aimed at exploring potential biological pathways and protein networks for insomnia characterized by wakefulness after sleep.

Method

Proteomics analysis was performed in the insomnia group with wakefulness and the control group. The differentially expressed proteins (DEPs) were enriched; then, hub proteins were identified by protein-protein interaction (PPI) network and verified by parallel reaction monitoring (PRM).

Results

Compared with the control group, the sleep time and efficiency of insomnia patients were decreased, and awakening time and numbers after sleep onset were significantly increased (P < 0.001). The results of proteomic sequencing found 68 DEPs in serum under 1.2-fold changed standard. These DEPs were significantly enriched in humoral immune response, complement and coagulation cascades, and cholesterol metabolism. Through the PPI network, we identified 10 proteins with the highest connectivity as hub proteins. Among them, the differential expression of 9 proteins was verified by PRM.

Conclusion

We identified the hub proteins and molecular mechanisms of insomnia patients characterized by wakefulness after sleep. It provided potential molecular targets for the clinical diagnosis and treatment of these patients and indicated that the immune and metabolic systems may be closely related to insomnia characterized by wakefulness after sleep.

Understanding the pathophysiological mechanisms of cardiometabolic complications in obstructive sleep apnoea: towards personalised treatment approaches

In January 2019, a European Respiratory Society research seminar entitled "Targeting the detrimental effects of sleep disturbances and disorders" was held in Dublin, Ireland. It provided the opportunity to critically review the current evidence of pathophysiological responses of sleep disturbances, such as sleep deprivation, sleep fragmentation or circadian misalignment and of abnormalities in physiological gases such as oxygen and carbon dioxide, which occur frequently in respiratory conditions during sleep. A specific emphasis of the seminar was placed on the evaluation of the current state of knowledge of the pathophysiology of cardiovascular and metabolic diseases in obstructive sleep apnoea (OSA). Identification of the detailed mechanisms of these processes is of major importance to the field and this seminar offered an ideal platform to exchange knowledge, and to discuss pitfalls of current models and the design of future collaborative studies. In addition, we debated the limitations of current treatment strategies for cardiometabolic complications in OSA and discussed potentially valuable alternative approaches.

Stress, sleep, and autonomic function in healthy adolescent girls and boys: Findings from the NCANDA study

OBJECTIVES

Starting in adolescence, female sex is a strong risk factor for the development of insomnia. Reasons for this are unclear but could involve altered stress reactivity and/or autonomic nervous system (ANS) dysregulation, which are strongly associated with the pathophysiology of insomnia. We investigated sex differences in the effect of stress on sleep and ANS activity in adolescents, using the first night in the laboratory as an experimental sleep-related stressor.

DESIGN

Repeated measures (first night vs. a subsequent night) with age (older/younger) and sex (males/females) as between factors.

SETTING

Recordings were performed at the human sleep laboratory at SRI International.

PARTICIPANTS

One hundred six healthy adolescents (Age, mean ± SD: 15.2 ± 2.0 years; 57 boys).

MEASURES

Polysomnographic sleep, nocturnal heart rate (HR), and frequency-domain spectral ANS HR variability (HRV) indices.

RESULTS

Boys and girls showed a first-night effect, characterized by lower sleep efficiency, lower %N1 and %N2 sleep, more wake after sleep onset and %N3 sleep, altered sleep microstructure (increased high-frequency sigma and Beta1 electroencephalographic activity), and reduced vagal activity (P < .05) on the first laboratory night compared to a subsequent night. The first night ANS stress effect (increases in HR and suppression in vagal HRV during rapid eye movement sleep) was greater in girls than boys (P < .05).

CONCLUSIONS

Sleep and ANS activity were altered during the first laboratory night in adolescents, with girls exhibiting greater ANS alterations than boys. Findings suggest that girls may be more vulnerable than boys to sleep-specific stressors, which could contribute to their increased risk for developing stress-related sleep disturbances.

The effect of body position on maternal cardiovascular function during sleep and wakefulness in late pregnancy

INTRODUCTION

An association between the increased risk of late stillbirth and the maternal supine sleeping position has been recently established. The risk of stillbirth following supine sleep has been suspected to occur as a result of aortocaval compression by the gravid uterus. A number of studies conducted during wakefulness have reported compromised cardiovascular function during supine rest, as demonstrated by reductions in cardiac output, blood pressure and utero-placental blood flow. It remains unclear whether similar effects are also present during sleep, due to the presence of key sleep-specific changes in cardiovascular function.

OBJECTIVE

To investigate the changes in maternal cardiovascular function between the supine and left-lateral positions during wakefulness and non-rapid eye movement (NREM) sleep in late pregnancy.

METHODS

Twenty-nine women with a singleton pregnancy between 24.7 and 36.7 weeks' gestation participated in a single overnight sleep study. Physiological measures (blood pressure, heart rate, heart rate variability - HRV, and pulse arrival time - PAT) were measured and recorded throughout the night using standard polysomnography equipment and the Portapres Model-2 device. As the present study evaluated cardiovascular changes during natural rest and sleep in pregnancy, participants were not given explicit instructions on which position to adopt. Body position was continuously recorded using a position monitor and verified with video recording.

RESULTS

No changes in systolic, diastolic or mean arterial blood pressure were observed between the left-lateral and supine positions during wakefulness or sleep. However, heart rate was significantly higher in the supine position compared to the left during wakefulness (p= .03), with a similar trend present during sleep (p= .11). A significantly shorter PAT was measured in the supine position (compared to the left) during wakefulness (p= .01) and sleep (p= .01). No change in HRV measures was observed between the left and supine positions in either state.

CONCLUSION

Blood pressure did not appear to differ significantly between the left-lateral and supine positions during wakefulness and sleep. The lack of blood pressure differences may reflect elevated sympathetic activity during rest and sleep in the supine position (compared to the left), suggesting that some degree of compensation for aortocaval compression may still be possible during sleep.

The Importance of Sleep Fragmentation on the Hemodynamic Dipping in Obstructive Sleep Apnea Patients

Introduction

Obstructive sleep apnea (OSA) has been associated with non-dipping blood pressure (BP). The precise mechanism is still under investigation, but repetitive oxygen desaturation and arousal induced sleep fragmentation are considered the main contributors.

Methods

We analyzed beat-to-beat measurements of hemodynamic parameters (HPs) during a 25-min period of wake–sleep transition. Differences in the mean HP values for heart rate (HR), systolic BP (SBP), and stroke volume (SV) during wake and sleep and their standard deviations (SDs) were compared between 34 controls (C) and 22 OSA patients. The Student’s t-test for independent samples and the effect size by Cohen’s d (d) were calculated. HP evolution was investigated by plotting the measured HP values against each consecutive pulse wave. After a simple regression analysis, the calculated coefficient beta (SCB) was used to indicate the HP evolution. We furthermore explored by a hierarchical block regression which variables increased the prediction for the SCB: model 1 BMI and age, model 2 + apnea/hypopnea index (AHI), and model 3 + arousal index (AI).

Results

Between the two groups, the SBP increased in OSA and decreased in C resulting in a significant difference (p = 0.001; d = 0.92). The SV demonstrated a similar development (p = 0.047; d = 0.56). The wake/sleep variation of the HP measured by the SD was higher in the OSA group—HR: p < 0.001; d = 1.2; SBP: p = 0.001; d = 0.94; and SV: p = 0.005; d = 0.82. The hierarchical regression analysis of the SCB demonstrated in SBP that the addition of AI to AHI resulted in ΔR²: +0.163 and ΔF + 13.257 (p = 0.001) and for SV ΔR²: +0.07 and ΔF 4.83 (p = 0.003). The AI but not the AHI remained statistically significant in the regression analysis model 3—SBP: β = 0.717, p = 0.001; SV: β = 0.469, p = 0.033.

Conclusion

In this study, we demonstrated that in OSA, the physiological dipping in SBP and SV decreased, and the variation of all investigated parameters increased. Hierarchical regression analysis indicates that the addition of the AI to BMI, age, and AHI increases the prediction of the HP evolution following sleep onset for both SBP and SV and may be the most important variable.

Changes in heart rate and blood pressure during nocturnal hot flashes associated with and without awakenings

Hot flashes (HFs) are a hallmark of menopause in midlife women. They are beyond bothersome symptoms, having a profound impact on quality of life and wellbeing, and are a potential marker of cardiovascular (CV) disease risk. Here, we investigated the impact on CV functioning of single nocturnal HFs, considering whether or not they were accompanied by arousals or awakenings. We investigated changes in heart rate (HR, 542 HFs), blood pressure (BP, 261 HFs), and pre-ejection period (PEP, 168 HFs) across individual nocturnal physiological HF events in women in the menopausal transition or post-menopause (age: 50.7 ± 3.6 years) (n = 86 for HR, 45 for BP, 27 for PEP). HFs associated with arousals/awakenings (51.1%), were accompanied by an increase in systolic (SBP; ~6 mmHg) and diastolic (DBP; ~5 mmHg) BP and HR (~20% increase), sustained for several minutes. In contrast, HFs occurring in undisturbed sleep (28.6%) were accompanied by a drop in SBP and a marginal increase in HR, likely components of the heat dissipation response. All HFs were accompanied by decreased PEP, suggesting increased cardiac sympathetic activity, with a prolonged increase for HFs associated with sleep disruption. Older age predicted greater likelihood of HF-related sleep disturbance. HFs were less likely to wake a woman in rapid-eye-movement and slow-wave sleep. Findings show that HFs associated with sleep disruption, which are in the majority and more likely in older women, lead to increases in HR and BP, which could have long-term impact on nocturnal CV restoration in women with multiple HFs.

Influence of quality of sleep in the first trimester on blood pressure in the third trimester in primipara women

Purpose: The purpose of this study was to clarify the relationship between decreased sleep quality during the first trimester and a rise in blood pressure during an otherwise normal course of pregnancy in primipara women. Materials and methods: We recruited 128 pregnant women (primipara) who visited the obstetrics and gynecology clinic for medical examination, of which 89 were longitudinally investigated from the first to the third trimester after obtaining informed consent. A survey was conducted in the first, second, and third trimesters to evaluate sleep quality using the Japanese version of the Pittsburgh Sleep Quality Index (PSQI-J). Patients were assigned to either a good sleep quality group (PSQI-J ≤ 5) or a poor sleep quality group (PSQI-J ≥ 6). Blood pressure was measured using a home blood pressure measurement method. We analyzed the relationship between sleep quality in the first trimester and blood pressure during pregnancy. Results: The increase in morning systolic blood pressure from first to third trimester was larger in the poor sleep quality group than in the good sleep quality group (7.1 ± 7.0 vs. 3.0 ± 5.6 mmHg, p < .01). Sleep latency (r = 0.38, β = 0.43, p = .02) and sleep disturbances (r = 0.24, β = 0.33, p = .04) in the first trimester affected the increase in systolic blood pressure during pregnancy. Conclusions: Understanding sleep quality at the beginning of pregnancy can help predict a rise in systolic blood pressure in the third trimester. This emphasizes the importance of sleep education during pregnancy.

Association between sleep disturbance and nocturnal blood pressure profiles by a linear mixed model analysis: the Nagahama study

OBJECTIVES

We aimed to analyze associations of sleep disturbance, including sleep disordered breathing, sleep fragmentation, and sleep efficiency, with abnormal nocturnal blood pressure (BP) profiles that may be risk factors for adverse cardiovascular outcomes.

METHODS

The study included 5854 community residents with 20,725 multi-day measurements. Sleep fragmentation and efficiency were evaluated using a wrist-worn activity monitor. Sleep disordered breathing was assessed using the 3% oxygen desaturation index corrected for actigraphy-determined sleep duration. A timer-equipped standard cuff-oscillometric device was used for home and sleep BP monitoring.

RESULTS

Mean nocturnal systolic BP (SBP) change was -8.6 ± 9.7% (-11.1 ± 12.6 mmHg), and inter-day correlation coefficient of the nocturnal SBP change was 0.443. Results of a linear mixed model analysis using daily measured values identified lower sleep efficiency (coefficient = -0.130, p < 0.001) as a determinant for decreased nocturnal SBP dipping beyond the interday variations of these parameters. Number of nocturnal urinations was another strong determinant (coefficient = 1.191, p < 0.001), although the association of sleep efficiency was independent of nocturnal urination, awake SBP, and sleep disordered breathing (coefficient = -0.102, p < 0.001). Sleep efficiency was also independently associated with sleep SBP level (coefficient = -0.138, p < 0.001). Estimated differences in nocturnal SBP dipping and sleep SBP level as a function of the degree of sleep efficiency (less than 80%) reached 1.63% (1.09-2.17%) and 2.16 mmHg (1.49-2.82%), respectively.

CONCLUSION

More attention should be paid to sleep efficiency as a factor in maintaining circadian BP rhythm.

Association of Adverse Pregnancy Outcomes With Self-Reported Measures of Sleep Duration and Timing in Women Who Are Nulliparous

STUDY OBJECTIVES

To examine the relationship of self-reported sleep during pregnancy with adverse pregnancy outcomes. A secondary objective was to describe the concordance between self-reported and objectively assessed sleep during pregnancy.

METHODS

In this prospective cohort, women completed a survey of sleep patterns at 6 to 13 weeks' gestation (visit 1) and again at 22 to 29 weeks' gestation (visit 3). Additionally, at 16 to 21 weeks (visit 2), a subgroup completed a week-long sleep diary coincident with an actigraphy recording. Weekly averages of self-reported sleep duration and sleep midpoint were calculated. A priori, sleep duration < 7 hours was defined as "short," and sleep midpoint after 5:00 AM was defined as "late." The relationship of these sleep abnormalities with hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) was determined.

RESULTS

Of the 10,038 women enrolled, sleep survey data were available for 7,524 women at visit 1 and 7,668 women at visit 3. A total of 752 women also provided ≥ 5 days of sleep diary data coincident with actigraphy at visit 2. We did not observe any consistent relationship between self-reported short sleep and HDP or GDM. There was an association between self-reported late sleep midpoint and GDM (visit 1 adjusted odds ratio 1.67, 95% confidence interval 1.17, 2.38; visit 2 adjusted odds ratio 1.73, 95% confidence interval 1.23, 2.43). At visit 2, 77.1% of participants had concordance between their diary and actigraphy for short sleep duration, whereas 94.3% were concordant for sleep midpoint.

CONCLUSIONS

Self-reported sleep midpoint, which is more accurate than self-reported sleep duration, is associated with the risk of GDM.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Title: Pregnancy as a Window to Future Cardiovascular Health: Adverse Pregnancy Outcomes as Predictors of Increased Risk Factors for Cardiovascular Disease, Identifier: NCT02231398, URL: https://clinicaltrials.gov/ct2/show/NCT02231398.

Dynamic coupling between the central and autonomic nervous systems during sleep: A review

Sleep is characterized by coordinated cortical and cardiac oscillations reflecting communication between the central (CNS) and autonomic (ANS) nervous systems. Here, we review fluctuations in ANS activity in association with CNS-defined sleep stages and cycles, and with phasic cortical events during sleep (e.g., arousals, K-complexes). Recent novel analytic methods reveal a dynamic organization of integrated physiological networks during sleep and indicate how multiple factors (e.g., sleep structure, age, sleep disorders) affect "CNS-ANS coupling". However, these data are mostly correlational and there is a lack of clarity of the underlying physiology, making it challenging to interpret causality and direction of coupling. Experimental manipulations (e.g., evoking K-complexes or arousals) provide information on the precise temporal sequence of cortical-cardiac activity, and are useful for investigating physiological pathways underlying CNS-ANS coupling. With the emergence of new analytical approaches and a renewed interest in ANS and CNS communication during sleep, future work may reveal novel insights into sleep and cardiovascular interactions during health and disease, in which coupling could be adversely impacted.

Out Like a Light? The Effects of a Diurnal Husbandry Schedule on Mouse Sleep and Behavior

Sleep disruption in humans, caused by shift work, can be detrimental to physical and behavioral health. Nocturnal laboratory mice may experience a similar disruption caused by human daytime activities, but whether this disruption affects their welfare is unknown. We used 48 mice (CD1, C57BL/6, and BALB/c of both sexes) in a factorial design to test a sleep disruption treatment, in which mice were disturbed by providing routine husbandry at either 1000 or 2200 during a 12:12-h light:dark cycle, with lights on at 0700. All mice were exposed for 1 wk to each disruption treatment, and we used a noninvasive sleep monitoring apparatus to monitor and record sleep. To determine whether providing nesting material ameliorated effects of sleep disruption, we tested 4 amounts of nesting material (3, 6, 9, or 12 g) and continuously recorded sleep in the home cage for 2 wk. C57BL/6 mice, regardless of sex or disruption timing, slept the least overall. There was a strong interaction of sex and type of mouse on sleep across 24 h. Mice slept less during the first day of the daytime disturbance than on day 6. These results suggest that disturbance timing affects sleep patterns in mice but not their overall amount of sleep and that the changes in sleep patterns vary between mouse type and sex. In addition, mice appear to both anticipate and acclimate to human activity during the day. Our welfare checks were possibly too predictable and inconsequential to induce true sleep disruption.

Environmental stressors and cardio-metabolic disease: part II-mechanistic insights

Environmental factors can act as facilitators of chronic non-communicable diseases. Ambient noise and air pollution collectively outrank all other environmental risk factors in importance, contributing to over 75% of the disease and disability burden associated with known environmental risk factors. In the first part of this review, we discussed the global burden and epidemiologic evidence supporting the importance of these novel risk factors as facilitators of cardiometabolic disease. In this part, we will discuss pathophysiological mechanisms responsible for noise and air pollution-mediated effects. Akin to traditional cardiovascular risk factors, a considerable body of evidence suggests that these environmental agents induce low-grade inflammation, oxidative stress, vascular dysfunction, and autonomic nervous system imbalance, thereby facilitating the development of diseases such as hypertension and diabetes. Through their impact on traditional risk factors and via additional novel mechanisms, environmental risk factors may have much larger impact on cardiovascular events than currently appreciated. In the second part of this review, we discuss deficiencies and gaps in knowledge and opportunities for new research.

Altered nocturnal blood pressure profiles in women with insomnia disorder in the menopausal transition

OBJECTIVE

Insomnia disorder is a risk factor for cardiovascular (CV) pathology. It is unknown whether insomnia that develops in the context of the menopausal transition (MT) impacts the CV system. We assessed nocturnal blood pressure (BP) and heart rate (HR) profiles in women with insomnia disorder in the MT.

METHODS

Twelve women meeting DSM-IV criteria for insomnia in the MT (age, mean ± SD: 50.5 ± 3.6 y) and 11 controls (age, mean ± SD: 49.0 ± 3.0 y) had polysomnographic recordings on one or two nights during which beat-to-beat BP and HR were assessed and analyzed hourly from lights-out across the first 6 hours of the night and according to sleep stage. Physiological hot flashes were identified from fluctuations in sternal skin conductance.

RESULTS

Women with insomnia and controls had similar distributions of sleep stages and awakenings/arousals across hours of the night, although insomnia participants tended to have more wakefulness overall. More women in the insomnia group (7 of 12) than in the control group (2 of 11) had at least one physiological hot flash at night (P < 0.05). Both groups showed a drop in BP in the first part of the night; however, systolic and diastolic BP patterns diverged later, remaining low in controls but increasing in insomnia participants 4 to 6 hours after lights-out (P < 0.05). Both groups showed a similar pattern of decline in HR across the night.

CONCLUSIONS

Our findings suggest altered regulatory control of BP during sleep in the MT insomnia. The causes and long-term consequences of this altered nocturnal BP profile remain to be determined.

Sleep Disturbances as a Risk Factor for Stroke

Sleep, a vital process of human being, is carefully orchestrated by the brain and consists of cyclic transitions between rapid eye movement (REM) and non-REM (NREM) sleep. Autonomic tranquility during NREM sleep is characterized by vagal dominance and stable breathing, providing an opportunity for the cardiovascular-neural axis to restore homeostasis, in response to use, distress or fatigue inflicted during wakefulness. Abrupt irregular swings in sympathovagal balance during REM sleep act as phasic loads on the resting cardiovascular system. Any causes of sleep curtailment or fragmentation such as sleep restriction, sleep apnea, insomnia, periodic limb movements during sleep, and shift work, not only impair cardiovascular restoration but also impose a stress on the cardiovascular system. Sleep disturbances have been reported to play a role in the development of stroke and other cardiovascular disorders. This review aims to provide updated information on the role of abnormal sleep in the development of stroke, to discuss the implications of recent research findings, and to help both stroke clinicians and researchers understand the importance of identification and management of sleep pathology for stroke prevention and care.

Heart rate phenotypes and clinical correlates in a large cohort of adults without sleep apnea

BACKGROUND

Normal sleep is associated with typical physiological changes in both the central and autonomic nervous systems. In particular, nocturnal blood pressure dipping has emerged as a strong marker of normal sleep physiology, whereas the absence of dipping or reverse dipping has been associated with cardiovascular risk. However, nocturnal blood pressure is not measured commonly in clinical practice. Heart rate (HR) dipping in sleep may be a similar important marker and is measured routinely in at-home and in-laboratory sleep testing.

METHODS

We performed a retrospective cross-sectional analysis of diagnostic polysomnography in a clinically heterogeneous cohort of n=1047 adults without sleep apnea.

RESULTS

We found that almost half of the cohort showed an increased HR in stable nonrapid eye movement sleep (NREM) compared to wake, while only 13.5% showed a reduced NREM HR of at least 10% relative to wake. The strongest correlates of HR dipping were younger age and male sex, whereas the periodic limb movement index (PLMI), sleep quality, and Epworth Sleepiness Scale (ESS) scores were not correlated with HR dipping. PLMI was however significantly correlated with metrics of impaired HR variability (HRV): increased low-frequency power and reduced high-frequency power. HRV metrics were unrelated to sleep quality or the ESS value. Following the work of Vgontzas et al, we also analyzed the sub-cohort with insomnia symptoms and short objective sleep duration. Interestingly, the sleep-wake stage-specific HR values depended upon insomnia symptoms more than sleep duration.

CONCLUSION

While our work demonstrates heterogeneity in cardiac metrics (HR and HRV), the population analysis suggests that pathological signatures of HR (nondipping and elevation) are common even in this cohort selected for the absence of sleep apnea. Future prospective work in clinical populations will further inform risk stratification and set the stage for testing interventions.

Sleep During Pregnancy: The nuMoM2b Pregnancy and Sleep Duration and Continuity Study

Study Objectives

To characterize sleep duration, timing and continuity measures in pregnancy and their association with key demographic variables.

Methods

Multisite prospective cohort study. Women enrolled in the nuMoM2b study (nulliparous women with a singleton gestation) were recruited at the second study visit (16-21 weeks of gestation) to participate in the Sleep Duration and Continuity substudy. Women <18 years of age or with pregestational diabetes or chronic hypertension were excluded from participation. Women wore a wrist activity monitor and completed a sleep log for 7 consecutive days. Time in bed, sleep duration, fragmentation index, sleep efficiency, wake after sleep onset, and sleep midpoint were averaged across valid primary sleep periods for each participant.

Results

Valid data were available from 782 women with mean age of 27.3 (5.5) years. Median sleep duration was 7.4 hours. Approximately 27.9% of women had a sleep duration of <7 hours; 2.6% had a sleep duration of >9 hours. In multivariable models including age, race/ethnicity, body mass index, insurance status, and recent smoking history, sleep duration was significantly associated with race/ethnicity and insurance status, while time in bed was only associated with insurance status. Sleep continuity measures and sleep midpoint were significantly associated with all covariates in the model, with the exception of age for fragmentation index and smoking for wake after sleep onset.

Conclusions

Our results demonstrate the relationship between sleep and important demographic characteristics during pregnancy.

Objectively measured short sleep duration and later sleep midpoint in pregnancy are associated with a higher risk of gestational diabetes

BACKGROUND

Experimental and epidemiologic data suggest that among nonpregnant adults, sleep duration may be an important risk factor for chronic disease. Although pregnant women commonly report poor sleep, few studies objectively evaluated the quality of sleep in pregnancy or explored the relationship between sleep disturbances and maternal and perinatal outcomes.

OBJECTIVE

Our objective was to examine the relationship between objectively assessed sleep duration, timing, and continuity (measured via wrist actigraphy) and maternal cardiovascular and metabolic morbidity specific to pregnancy.

STUDY DESIGN

This was a prospective cohort study of nulliparous women. Women were recruited between 16 0/7 and 21 6/7 weeks' gestation. They were asked to wear a wrist actigraphy monitor and complete a daily sleep log for a period of 7 consecutive days. The primary sleep exposure variables were the averages of the following over the total valid nights (minimum 5, maximum 7 nights): short sleep duration during the primary sleep period (<7 h/night), late sleep midpoint (midpoint between sleep onset and sleep offset >5 am), and top quartile of minutes of wake time after sleep onset and sleep fragmentation index. The primary outcomes of interest were a composite of hypertensive disorders of pregnancy (mild, severe, or superimposed preeclampsia; eclampsia; or antepartum gestational hypertension) and gestational diabetes mellitus. We used χ² tests to assess associations between sleep variables and categorical baseline characteristics. Crude odds ratios and 95% confidence intervals were estimated from univariate logistic regression models to characterize the magnitude of the relationship between sleep characteristics and hypertensive disorders of pregnancy and gestational diabetes. For associations significant in univariate analysis, multiple logistic regression was used to explore further the association of sleep characteristics with pregnancy outcomes.

RESULTS

In all, 901 eligible women consented to participate; 782 submitted valid actigraphy studies. Short sleep duration and a later sleep midpoint were associated with an increased risk of gestational diabetes (odds ratio, 2.24; 95% confidence interval, 1.11-4.53; and odds ratio, 2.58; 95% confidence interval, 1.24-5.36, respectively) but not of hypertensive disorders. A model with both sleep duration and sleep midpoint as well as their interaction term revealed that while there was no significant interaction between these exposures, the main effects of both short sleep duration and later sleep midpoint with gestational diabetes remained significant (adjusted odds ratio, 2.06; 95% confidence interval, 1.01-4.19; and adjusted odds ratio, 2.37; 95% confidence interval, 1.13-4.97, respectively). Additionally, after adjusting separately for age, body mass index, and race/ethnicity, both short sleep duration and later sleep midpoint remained associated with gestational diabetes. No associations were demonstrated between the sleep quality measures (wake after sleep onset, sleep fragmentation) and hypertensive disorders or gestational diabetes.

CONCLUSION

Our results demonstrate a relationship between short sleep duration and later sleep midpoint with gestational diabetes. Our data suggest independent contributions of these 2 sleep characteristics to the risk for gestational diabetes in nulliparous women.

Morning surge in blood pressure and sympathetic activity in Mongolians and Han Chinese: a multimodality investigation of hypertension and dyssomnia

Background

Hypertension and dyssomnia are increasing significantly in Mongolians, and the related factors of ethnic differences in hypertension and dyssomnia between Mongolians and Han Chinese are unclear. This study examined the relationship of morning surge in blood pressure (MBP) with ethnicity, sleep situation, and sympathetic activity throughout the day.

Methods

Of 692 hypertensive patients screened, 202 subjects with dyssomnia were selected. They were then divided into Mongolian (n = 87) and Han (n = 115) groups. The differences in dyssomnia, 24-h blood pressure, and urinary catecholamine were analyzed in all subjects; they were then further divided according to the degree of dyssomnia (low, moderate, and severe) to determine the differences in blood pressure and catecholamine.

Results

Mongolians had a lower history of smoking, daytime dysfunction, nocturnal heart rates, and dopamine levels, but their body mass index, triglyceride, fasting glucose, morning surge in systolic blood pressure (MSBP), nocturnal systolic blood pressure (NSBP), nocturnal diastolic blood pressure, daytime systolic blood pressure, daytime heart rates, and dopamine level (D-DA) were higher than those of Han Chinese. With the aggravation of dyssomnia, MSBP, NSBP, D-NE, daytime epinephrine, and D-DA of Mongolians and Han Chinese increased gradually, but the rate of increase was faster in the latter (p < 0.05). D-DA was entered into the MSBP regression model of Mongolians (intercept, 157 mmHg), whereas D-DA and D-NE were entered into the MSBP regression model of Han Chinese (intercept, 142 mmHg).

Conclusion

Worsened dyssomnia induces higher MSBP and augments sympathetic excitability in Mongolians and Han Chinese. Mongolians with hypertension and dyssomnia had higher MSBP baseline and D-DA but lower N-DA. With an increase in D-DA, MSBP in Han and Mongolian patients increased gradually.

Cardiovascular Consequences of Repetitive Arousals over the Entire Sleep Duration

OBJECTIVES

To explore the cardiovascular effects of nightlong repetitive arousals (RA).

METHODS

Twenty healthy subjects participated in two consecutive sleep studies. The first one was free of intervention and the second study involved repetitive arousals induced by acoustical stimuli. Blood pressure, heart rate variability (HRV), arterial stiffness index (ASI), and serum markers including nitric oxide (NO), endothelin-1 (ET-1), C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF) were studied.

RESULTS

RA led to overnight elevation in diastolic blood pressure (DBP) but not in systolic blood pressure (SBP). Regarding HRV, overnight increase in low frequency power (LF) and low frequency to high frequency ratio (LHR) and decrease in high frequency power (HF) were evident. The relative overnight differences in HF and LHR correlated with the amount of rapid-eye movement (REM) sleep. RA did not cause detectable change in either ASI or serum markers of interest.

CONCLUSIONS

Nightlong RA alters the sympathovagal modulation significantly and this effect seems to be associated with the amount of REM sleep. Exposure to RA also causes an elevation in postsleep DBP. Disturbance to autonomic nervous system (ANS) may precede endothelial dysfunction and increased arterial stiffness as cardiovascular consequences of RA.

Noise Pollution and Arterial Hypertension

Noise exposure modifies the function of multiple organs and systems. Acute noise exposure - both in laboratory settings where traffic noise is simulated and in real-life working environments - can cause increases in blood pressure, heart rate and cardiac output. This review examines the effects of noise pollution on the cardiovascular system, with a particular focus on non-auditory effects such as noise-induced arterial hypertension.

A Relationship between Periodic Limb Movements in Sleep and High Nocturnal Blood Pressure Values in Patients with Insomnia

STUDY OBJECTIVES

Insomnia, which is the most common sleep disorder, is a significant public health burden. Growing evidence suggests the existence of a relationship between insomnia and hypertension. The aim of this study was to verify the hypothesis that periodic limb movements in sleep (PLMS) are related to increased nocturnal blood pressure (BP) values in patients with insomnia.

METHODS

We retrospectively analyzed polysomnographic recordings of patients with insomnia who were seen in our clinic from January to December 2012. Patients were divided into two groups based on their nocturnal BP values: group I had normal nocturnal BP values (n = 27) and group II (n = 29) had elevated nocturnal BP values. The sleep architecture of the groups was compared.

RESULTS

The groups did not differ in terms of age, sex, or the prevalence of cardiovascular disorders. However, we found that the number of PLMS was significantly higher in group II than in group I (PLMS index: 18.8 vs. 6.5; p = 0.01).

CONCLUSIONS

Our results suggest that PLMS are related to increased nocturnal BP values in patients with insomnia, which may partly explain the relationship between insomnia and hypertension. Therefore, it is possible that treatment of PLMS may normalize nocturnal BP in patients with insomnia.

Associations between sleep difficulties and risk factors for cardiovascular disease in veterans and active duty military personnel of the Iraq and Afghanistan conflicts

Recent evidence suggests that sleep disturbance may play an important role in the development of cardiovascular disease (CVD). Despite the prevalence of sleep complaints among service members of recent military conflicts, few studies have examined associations between sleep and risk factors for CVD in this population. Symptom checklist items regarding distress about "trouble falling asleep" and "restless/disturbed sleep" were used as proxies for sleep onset and maintenance difficulties to examine these associations in US military service members of recent conflicts. Veterans having both sleep onset and maintenance difficulties had greater odds of being a current smoker and having psychiatric symptoms and diagnoses. Increased odds of a self-reported hypertension diagnosis and elevated systolic blood pressure were also found in certain subsets of this sample. Findings highlight the need for greater recognition of sleep difficulties as a CVD risk factor in a population known to be at increased risk for this condition.

Sleep and multisystem biological risk: a population-based study

Background

Short sleep and poor sleep quality are associated with risk of cardiovascular disease, diabetes, cancer, and mortality. This study examines the contribution of sleep duration and sleep quality on a multisystem biological risk index that is known to be associated with morbidity and mortality.

Methods

Analyses include a population-based sample from the Midlife Development in the United States survey recruited to the Biomarker substudy. A total of 1,023 participants aged 54.5 years (SD = 11.8), 56% female and 77.6% white, were included in the analyses. A multisystem biological risk index was derived from 22 biomarkers capturing cardiovascular, immune, lipid-metabolic, glucose-metabolic, sympathetic, parasympathetic, and hypothalamic-pituitary-adrenal systems. Self-reported average sleep duration was categorized as short (<5 hrs), below normal (5 to <6.5 hrs), normal (6.5 to <8.5 hrs), and long sleepers (8.5+ hrs). Sleep quality was determined using the Pittsburgh Sleep Quality Index categorized as normal (≤5) and poor quality (>5) sleep.

Findings

Linear mixed effect models adjusting for age, gender, race, education, income, BMI, and health status were performed. As compared to normal sleepers, multisystem biological risk in both short (B(SE) = .38(.15), p<.01) and long sleepers (B(SE) = .28(.11), p<.01) were elevated. Poor quality sleep alone was associated with elevated multisystem biological risk (B(SE) = .15(.06), p = .01), but was not significant after adjustment for health status. All short sleepers reported poor sleep quality. However in the long sleepers, only those who reported poor sleep quality exhibited elevated multisystem biological risk (B(SE) = .93(.3), p = .002).

Conclusions

Self-reported poor sleep quality with either short or long sleep duration is associated with dysregulation in physiological set points across regulatory systems, leading to elevated multisystem biological risk. Physicians should inquire about sleep health in the assessment of lifestyle factors related to disease risk, with evidence that healthy sleep is associated with lower multisystem biological risk.

Metabolic dysfunction in obstructive sleep apnea: A critical examination of underlying mechanisms

It has recently become clear that obstructive sleep apnea (OSA) is an independent risk factor for the development of metabolic syndrome, a disorder of defective energy storage and use. Several mechanisms have been proposed to explain this finding, drawing upon the characteristics that define OSA. In particular, intermittent hypoxia, sleep fragmentation, elevated sympathetic tone, and oxidative stress - all consequences of OSA - have been implicated in the progression of poor metabolic outcomes in OSA. In this review we examine the evidence to support each of these disease manifestations of OSA as a unique risk for metabolic dysfunction. Tissue hypoxia and sleep fragmentation are each directly connected to insulin resistance and hypertension, and each of these also may increase sympathetic tone, resulting in defective glucose homeostasis, excessive lipolysis, and elevated blood pressure. Oxidative stress further worsens insulin resistance and in turn, metabolic dysfunction also increases oxidative stress. However, despite many studies linking each of these individual components of OSA to the development of metabolic syndrome, there are very few reports that actually provide a coherent narrative about the mechanism underlying metabolic dysfunction in OSA.

Cardiovascular effects of environmental noise exposure

The role of noise as an environmental pollutant and its impact on health are being increasingly recognized. Beyond its effects on the auditory system, noise causes annoyance and disturbs sleep, and it impairs cognitive performance. Furthermore, evidence from epidemiologic studies demonstrates that environmental noise is associated with an increased incidence of arterial hypertension, myocardial infarction, and stroke. Both observational and experimental studies indicate that in particular night-time noise can cause disruptions of sleep structure, vegetative arousals (e.g. increases of blood pressure and heart rate) and increases in stress hormone levels and oxidative stress, which in turn may result in endothelial dysfunction and arterial hypertension. This review focuses on the cardiovascular consequences of environmental noise exposure and stresses the importance of noise mitigation strategies for public health.

Sleep is associated with the metabolic syndrome in a multi-ethnic cohort of midlife women: the SWAN Sleep Study

STUDY OBJECTIVES

We evaluated associations among subjective and objective measures of sleep and the metabolic syndrome in a multi-ethnic sample of midlife women.

DESIGN

Cross-sectional study.

SETTING

Participants' homes.

PARTICIPANTS

Caucasian (n = 158), African American (n = 125), and Chinese women (n = 57); mean age = 51 years. Age range = 46-57 years.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Metabolic syndrome was measured in the clinic and sleep quality was assessed by self-report. Indices of sleep duration, continuity/fragmentation, depth, and sleep disordered breathing were assessed by in-home polysomnography (PSG). Covariates included sociodemographics, menopausal status, use of medications that affect sleep, and self-reported health complaints and health behaviors known to influence metabolic syndrome risk. Logistic regression was used to test the hypothesis that the metabolic syndrome would be associated with increased subjective sleep complaints and PSG-assessed sleep disturbances. In univariate analyses, the metabolic syndrome was associated with decreased sleep duration and efficiency and increased NREM beta power and apnea-hypopnea index (AHI). After covariate adjustment, sleep efficiency (odds ratio [OR] = 2.06, 95% confidence interval [CI]: 1.08-3.93), NREM beta power (OR = 2.09, 95% CI: 1.09-3.98), and AHI (OR = 1.86, 95% CI: 1.40-2.48) remained significantly associated with the metabolic syndrome (odds ratio values are expressed in standard deviation units). These relationships did not differ by race.

CONCLUSIONS

Objective indices of sleep continuity, depth, and sleep disordered breathing are significant correlates of the metabolic syndrome in midlife women, independent of race, menopausal status and other factors that might otherwise account for these relationships.

Sleep/wake estimation using only anterior tibialis electromyography data

BACKGROUND

In sleep efficiency monitoring system, actigraphy is the simplest and most commonly used device. However, low specificity to wakefulness of actigraphy was revealed in previous studies. In this study, we assumed that sleep/wake estimation using actigraphy and electromyography (EMG) signals would show different patterns. Furthermore, each EMG pattern in two states (sleep, wake during sleep) was analysed. Finally, we proposed two types of method for the estimation of sleep/wake patterns using only EMG signals from anterior tibialis muscles and the results were compared with PSG data.

METHODS

Seven healthy subjects and five patients (2 obstructive sleep apnea, 3 periodic limb movement disorder) participated in this study. Night time polysomnography (PSG) recordings were conducted, and electrooculogram, EMG, electroencephalogram, electrocardiogram, and respiration data were collected. Time domain analysis and frequency domain analysis were applied to estimate the sleep/wake patterns. Each method was based on changes in amplitude or spectrum (total power) of anterior tibialis electromyography signals during the transition from the sleep state to the wake state. To obtain the results, leave-one-out-cross-validation technique was adopted.

RESULTS

Total sleep time of the each group was about 8 hours. For healthy subjects, the mean epoch-by-epoch results between time domain analysis and PSG data were 99%, 71%, 80% and 0.64 (sensitivity, specificity, accuracy and kappa value), respectively. For frequency domain analysis, the corresponding values were 99%, 73%, 81% and 0.67, respectively. Absolute and relative differences between sleep efficiency index from PSG and our methods were 0.8 and 0.8% (for frequency domain analysis). In patients with sleep-related disorder, our proposed methods revealed the substantial agreement (kappa > 0.61) for OSA patients and moderate or fair agreement for PLMD patients.

CONCLUSIONS

The results of our proposed methods were comparable to those of PSG. The time and frequency domain analyses showed the similar sleep/wake estimation performance.

Sleep bruxism is associated with a rise in arterial blood pressure

STUDY OBJECTIVES

Sleep bruxism (SB) is a movement disorder identified by grinding of teeth and rhythmic masticatory muscle activity (RMMA). RMMA is associated with body movements and cortical arousals. Increases in autonomic sympathetic activities that characterize sleep cortical arousal precede RMMA/SB. Based on these findings, this study examined whether RMMA/SB episodes are also associated with significant changes in arterial blood pressure (BP).

DESIGN

Participants underwent 3 nights of full polysomnography that included noninvasive beat-to-beat BP recording. Single RMMA/SB episodes and arousal episodes were analyzed in stage 2 sleep and categorized as: (i) RMMA/SB + arousal; (ii) RMMA/SB + body movement; (iii) RMMA/SB + arousal + body movement; or (iv) arousal alone. Sleep and RMMA/SB data were compared to a Non SB group. RMMA/SB clusters (RMMA/SB episodes ≤ 30 sec apart) were also analyzed.

SETTING

Sleep Laboratory at l'Hôpital du Sacré-Coeur de Montréal.

PARTICIPANTS

Ten young, healthy participants with SB (mean age = 26 ± 1.8 years) and 9 without SB (mean age = 29 ± 1.2 years).

INTERVENTIONS

N/A MEASUREMENTS AND RESULTS: BP increased with all RMMA/SB and arousal episodes (P ≤ 0.05). The average maximum BP surges (systolic/diastolic ± SE mm Hg) were: 25.6 ± 3.3/12.6 ± 2.0 for RMMA/SB + arousal; 30.1 ± 1.7/19.1 ± 1.9 for RMMA/SB + body movement; 26.0 ± 2.8/15.1 ± 2.0 for RMMA/SB + arousal + body movement; 19.4 ± 2.3/8.9 ± 1.2 for arousal alone; and for RMMA/SB clusters: Episode: 1: 26.2 ± 8.7/16.4 ± 5.7; Episode 2: 21.1 ± 7.9/12.6 ± 6.4.

CONCLUSION

Rhythmic masticatory muscle activity/sleep bruxism (RMMA/SB) is associated with blood pressure fluctuations during sleep. Arousals and body movements often occur with RMMA/SB and can impact the magnitude of this BP surge.

A Moderate Increase of Physiological CO(2) in a Critical Range during Stable NREM Sleep Episode: A Potential Gateway to REM Sleep

Sleep is characterized as rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. Studies suggest that wake-related neurons in the basal forebrain, posterior hypothalamus and brainstem, and NREM sleep-related neurons in the anterior-hypothalamic area inhibit each other, thus alternating sleep-wakefulness. Similarly, pontine REM-ON and REM-OFF neurons reciprocally inhibit each other for REM sleep modulation. It has been proposed that inhibition of locus coeruleus (LC) REM-OFF neurons is pre-requisite for REM sleep genesis, but it remains ambiguous how REM-OFF neurons are hyperpolarized at REM sleep onset. The frequency of breathing pattern remains high during wake, slows down during NREM sleep but further escalates during REM sleep. As a result, brain CO(2) level increases during NREM sleep, which may alter REM sleep manifestation. It has been reported that hypocapnia decreases REM sleep while hypercapnia increases REM sleep periods. The groups of brainstem chemosensory neurons, including those present in LC, sense the alteration in CO(2) level and respond accordingly. For example, one group of LC neurons depolarize while other hyperpolarize during hypercapnia. In another group, hypercapnia initially depolarizes but later hyperpolarizes LC neurons. Besides chemosensory functions, LC REM-OFF neurons are an integral part of REM sleep executive machinery. We reason that increased CO(2) level during a stable NREM sleep period may hyperpolarize LC neurons including REM-OFF, which may help initiate REM sleep. We propose that REM sleep might act as a sentinel to help maintain normal CO(2) level for unperturbed sleep.

Sleep and cardiovascular regulation

Normal sleep has a profound effect on the cardiovascular system, reducing cardiovascular activity throughout non-rapid eye movement sleep; changes that are modified and augmented by circadian system influence. There is also evidence that sleep-initiated changes in autonomic balance may in turn modify the development of sleep within a night, particularly the development of slow wave sleep. It is assumed that the cardiovascular changes that accompany sleep reflect a functional aspect of sleep, although the precise functional role has not been agreed upon. Nevertheless, there is good evidence that the cardiovascular changes that occur during normal sleep are beneficial for the cardiovascular system. Arousals from sleep, which are common even in normal sleep, are associated with a surge in activity in cardiorespiratory systems, with marked effects on the sleep-related pattern of cardiovascular activity when they occur frequently. Despite the importance of this aspect of sleep, controversy remains as to both the nature of the activation response and the circumstances under which it is elicited. The concept that sleep-related changes in cardiovascular activity are beneficial leads to the corollary that sleep disturbance would result in adverse cardiovascular consequences. While there is strong empirical evidence for such a relationship, it remains unclear whether this is a direct effect or, as has been suggested recently, the effect of disturbed sleep is mediated via stress-related modification of neuroendocrine systems.

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.

Effects of selective slow-wave sleep deprivation on nocturnal blood pressure dipping and daytime blood pressure regulation

Nocturnal blood pressure (BP) decline or "dipping" is an active, central, nervously governed process, which is important for BP regulation during daytime. It is, however, not known whether the sleep process itself or, more specifically, slow-wave sleep (SWS) is important for normal dipping. Therefore, in the present study, healthy subjects (6 females, 5 males) were selectively deprived of SWS by EEG-guided acoustic arousals. BP and heart rate (HR) were monitored during experimental nights and the following day. Additionally, nocturnal catecholamine excretion was determined, and morning baroreflex function was assessed by microneurographic measurements of muscle sympathetic nerve activity (MSNA) and heart rate variability (HRV). Data were compared with a crossover condition of undisturbed sleep. SWS was successfully deprived leading to significantly attenuated mean arterial BP dipping during the first half (P < 0.05), but not during the rapid-eye-movement-dominated second half of total sleep; however, dipping still evolved even in the absence of SWS. No differences were found for nighttime catecholamine excretion. Moreover, daytime resting and ambulatory BP and HR were not altered, and morning MSNA and HRV did not differ significantly, indicating that baroreflex-mediated sympathoneural BP regulation was not affected by the preceding SWS deprivation. We conclude that in healthy humans the magnitude of nocturnal BP dipping is significantly affected by sleep depth. Deprivation of SWS during one night does not modulate the morning threshold and sensitivity of the vascular and cardiac baroreflex and does not alter ambulatory BP during daytime.