Repetitive exposure to shortened sleep leads to blunted sleep-associated blood pressure dipping

The association between sleep duration and muscle sympathetic nerve activity

PURPOSE

Sleep duration is associated with risk of hypertension and cardiovascular diseases. It is thought that shorter sleep increases sympathetic activity. However, most studies are based on acute experimental sleep deprivation that have produced conflicting results. Furthermore, there are limited data available on habitual sleep duration and gold-standard measures of sympathetic activation. Hence, this study aimed to assess the association between habitual sleep duration and muscle sympathetic nerve activity.

METHODS

Twenty-four participants aged ≥ 18 years were included in the study. Sleep was assessed using at-home 7-day/night actigraphy (ActiGraph™ GT3X-BT) and sleep questionnaires (Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale). Microelectrode recordings of muscle sympathetic nerve activity were obtained from the common peroneal nerve. Participants were categorised into shorter or longer sleep duration groups using a median split of self-report and actigraphy sleep measures.

RESULTS

Compared to longer sleepers, shorter sleepers averaged 99 ± 40 min and 82 ± 40 min less sleep per night as assessed by self-report and objective measures, respectively. There were no differences in age (38 ± 18 vs 39 ± 21 years), sex (5 male, 7 female vs 6 male, 6 female), or body mass index (23 ± 3 vs 22 ± 3 kg/m2) between shorter and longer sleepers. Expressed as burst frequency, muscle sympathetic nerve activity was higher in shorter versus longer sleepers for both self-report (39.4 ± 12.9 vs 28.4 ± 8.5 bursts/min, p = 0.019) and objective (37.9 ± 12.4 vs 28.1 ± 8.8 bursts/min, p = 0.036) sleep duration.

CONCLUSIONS

Shorter sleep duration assessed in a home setting was associated with higher muscle sympathetic nerve activity. Sympathetic overactivity may underlie the association between short sleep and hypertension.

Insights into vascular physiology from sleep photoplethysmography

STUDY OBJECTIVES

Photoplethysmography (PPG) in consumer sleep trackers is now widely available and used to assess heart rate variability (HRV) for sleep staging. However, PPG waveform changes during sleep can also inform about vascular elasticity in healthy persons who constitute a majority of users. To assess its potential value, we traced the evolution of PPG pulse waveform during sleep alongside measurements of HRV and blood pressure (BP).

METHODS

Seventy-eight healthy adults (50% male, median [IQR range] age: 29.5 [23.0, 43.8]) underwent overnight polysomnography (PSG) with fingertip PPG, ambulatory blood pressure monitoring, and electrocardiography (ECG). Selected PPG features that reflect arterial stiffness: systolic to diastolic distance (∆T_norm), normalized rising slope (Rslope) and normalized reflection index (RI) were derived using a custom-built algorithm. Pulse arrival time (PAT) was calculated using ECG and PPG signals. The effect of sleep stage on these measures of arterial elasticity and how this pattern of sleep stage evolution differed with participant age were investigated.

RESULTS

BP, heart rate (HR) and PAT were reduced with deeper non-REM sleep but these changes were unaffected by the age range tested. After adjusting for lowered HR, ∆T_norm, Rslope, and RI showed significant effects of sleep stage, whereby deeper sleep was associated with lower arterial stiffness. Age was significantly correlated with the amount of sleep-related change in ∆T_norm, Rslope, and RI, and remained a significant predictor of RI after adjustment for sex, body mass index, office BP, and sleep efficiency.

CONCLUSIONS

The current findings indicate that the magnitude of sleep-related change in PPG waveform can provide useful information about vascular elasticity and age effects on this in healthy adults.

Recovery Sleep After Sleep Restriction Is Insufficient to Return Elevated Daytime Heart Rate and Systolic Blood Pressure to Baseline Levels

OBJECTIVE

Sleep restriction alters daytime cardiac activity, including elevating heart rate (HR) and blood pressure (BP). There is minimal research on the cumulative effects of sleep loss and the response after subsequent recovery sleep on HR and BP. This study examined patterns of HR and BP across baseline, sleep restriction, and recovery conditions using multiple daytime cardiac measurements.

METHODS

Participants (15 healthy men, mean [standard deviation] = 22.3 [2.8] years) completed an 11-day inpatient protocol with three nights of 10 hours/night baseline sleep opportunity, five sleep restriction nights (5-hour/night sleep opportunity), and two recovery nights (10-hour/night sleep opportunity). Resting HR and BP were measured every 2 hours during wake. Multilevel models with random effects for individuals examined daytime HR and BP across study conditions and days into the study.

RESULTS

Mean daytime HR was 1.2 (0.5) beats/min lower during sleep restriction compared with baseline ( p < .001). During recovery, HR was 5.5 (1.0) beats/min higher ( p < .001), and systolic BP (SBP) was 2.9 (1.1) mm Hg higher ( p = .009). When accounting for days into the study (irrespective of condition) and measurement timing across the day, HR increased by 7.6 beats/min and SBP increased by 3.4 mm Hg across the study period ( p < .001).

CONCLUSIONS

Our findings suggest that daytime HR and SBP increase after successive nights of sleep restriction, even after accounting for measurement time of day. HR and SBP did not recover to baseline levels after two recovery nights of sleep, suggesting that longer recovery sleep may be necessary to recover from multiple, consecutive nights of moderate sleep restriction.

Evaluation of the Diurnal Cycle of Blood Pressure and Sleep in Shift Workers

BACKGROUND

Circadian misalignment of physiological factors in shift workers is poorly studied in the Indian population. In the present study, 24-hour blood pressure measurements were taken on the same subject twice, once during his morning and night shifts. Sleep was also monitored by a self-reported sleep diary, which was confirmed with an activity monitor, and the sleep quality was assessed using sleep questionnaires.

OBJECTIVE

This study aimed to discover the pattern of blood pressure variation, the dipping and non-dipping status, and its correlation with sleep.

METHODOLOGY

This observational study was conducted in the Department of Physiology, All India Institute of Medical Sciences (AIIMS), Rishikesh, from April 2019 to September 2019, among security guards working rotating shifts in the Rishikesh hospital premises. Participants were given an activity sheet with instructions to document their daily activities for a complete 24-hour period on the designated measurement day, including recording the time of waking up and going to sleep. A wrist-worn activity monitor was utilised to assess the self-reported sleep duration provided by each participant on the activity sheet.

RESULTS

The present study showed the mean age of the participants as 27.03 ± 2.71 years, along with a mean body mass index (BMI) of 22.10 ± 1.64. Sleep duration was significantly higher during the morning shift (5.81 ± 1.08 hours) compared to the night shift (4.02 ± 1.70 hours) on the day of ambulatory blood pressure monitoring (ABPM) recording. The mean difference in systolic blood pressure between night shift workers between their awake and sleep periods was 15.91 ± 8.44 mmHg. However, no statistically significant disparity was seen when comparing the systolic blood pressure at the 24-hour mark during wakefulness and sleep between those working morning and night shifts (p >0.05).

CONCLUSION

The current study's findings indicate that participation in shift work, particularly night shift work, could potentially play a role in the emergence of irregular circadian blood pressure patterns and potentially lead to a lack of nocturnal blood pressure decline.

Beyond the symptom: the biology of fatigue

A workshop titled "Beyond the Symptom: The Biology of Fatigue" was held virtually September 27-28, 2021. It was jointly organized by the Sleep Research Society and the Neurobiology of Fatigue Working Group of the NIH Blueprint Neuroscience Research Program. For access to the presentations and video recordings, see: https://neuroscienceblueprint.nih.gov/about/event/beyond-symptom-biology-fatigue. The goals of this workshop were to bring together clinicians and scientists who use a variety of research approaches to understand fatigue in multiple conditions and to identify key gaps in our understanding of the biology of fatigue. This workshop summary distills key issues discussed in this workshop and provides a list of promising directions for future research on this topic. We do not attempt to provide a comprehensive review of the state of our understanding of fatigue, nor to provide a comprehensive reprise of the many excellent presentations. Rather, our goal is to highlight key advances and to focus on questions and future approaches to answering them.

Effect of Short versus Long Duration Naps on Blood Pressure during Simulated Night Shift Work: A Randomized Crossover Trial

OBJECTIVE

Blunting of the sleep-related dip in blood pressure (BP) has been linked to numerous cardiovascular outcomes including myocardial infarction. Blunting of BP dipping occurs during night shift work and previous research suggest that a 60-min or longer on-shift nap is needed to restore normal/healthy BP dipping. We sought to determine the effect of different durations of napping on BP during and following simulated night shifts. We hypothesized that the greatest benefit in terms of restoration of normal BP dipping during night shift work would be observed during a longer duration nap versus a shorter nap opportunity.

METHODS

We used a randomized crossover laboratory-based study design. Participants consented to complete three separate 72-hr conditions that included a 12-hr simulated night shift. Nap conditions included a 30-min and 2-hr nap compared to a no-nap condition. Ambulatory BP monitoring was assessed hourly and every 10-30 mins during in-lab naps. Blunted BP dipping during in-lab naps was the primary outcome. Goal enrollment of 25 (35 with attrition) provided 80% power to detect a mean difference of 5 mmHg in BP between nap conditions.

RESULTS

Of the 58 screened, 28 were consented, and 26 completed all three 72-hr conditions. More than half (53.6%) were female. Mean age was 24.4 years (SD7.2). Most (85.7%) were certified as emergency medical technicians or paramedics. The mean percentage dip in systolic BP (SBP) and diastolic BP (DBP) did not differ between the 30-min and 2-hr nap conditions (p > 0.05), yet a greater proportion of participants experienced a 10-20% dip in SBP or DBP during the 2-hr nap versus the 30-min nap (p < 0.05). For every additional minute of total sleep during the 30-min nap, the percentage of SBP dip improved by 0.60%, and the percentage of DBP dip improved by 0.68% (p < 0.05). These improvements approximate to a 6% per minute relative advancement toward normal/healthy BP dipping.

CONCLUSIONS

Restoration of a normal/healthy dip in BP is achievable during short and long duration nap opportunities during simulated night shift work. Our findings support the hypothesis that BP dipping is more common during longer 2-hr versus shorter 30-min naps.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04469803. Registered on 9 July 2020.

Wildfire-related smoke inhalation worsens cardiovascular risk in sleep disrupted rats

Introduction

As a lifestyle factor, poor sleep status is associated with increased cardiovascular morbidity and mortality and may be influenced by environmental stressors, including air pollution.

Methods

To determine whether exposure to air pollution modified cardiovascular effects of sleep disruption, we evaluated the effects of single or repeated (twice/wk for 4 wks) inhalation exposure to eucalyptus wood smoke (ES; 964 μg/m3 for 1 h), a key wildland fire air pollution source, on mild sleep loss in the form of gentle handling in rats. Blood pressure (BP) radiotelemetry and echocardiography were evaluated along with assessments of lung and systemic inflammation, cardiac and hypothalamic gene expression, and heart rate variability (HRV), a measure of cardiac autonomic tone.

Results and Discussion

GH alone disrupted sleep, as evidenced by active period-like locomotor activity, and increases in BP, heart rate (HR), and hypothalamic expression of the circadian gene Per2. A single bout of sleep disruption and ES, but neither alone, increased HR and BP as rats transitioned into their active period, a period aligned with a critical early morning window for stroke risk in humans. These responses were immediately preceded by reduced HRV, indicating increased cardiac sympathetic tone. In addition, only sleep disrupted rats exposed to ES had increased HR and BP during the final sleep disruption period. These rats also had increased cardiac output and cardiac expression of genes related to adrenergic function, and regulation of vasoconstriction and systemic blood pressure one day after final ES exposure. There was little evidence of lung or systemic inflammation, except for increases in serum LDL cholesterol and alanine aminotransferase. These results suggest that inhaled air pollution increases sleep perturbation-related cardiovascular risk, potentially in part by increased sympathetic activity.

Toward Precision Medicine: Circadian Rhythm of Blood Pressure and Chronotherapy for Hypertension - 2021 NHLBI Workshop Report

Healthy individuals exhibit blood pressure variation over a 24-hour period with higher blood pressure during wakefulness and lower blood pressure during sleep. Loss or disruption of the blood pressure circadian rhythm has been linked to adverse health outcomes, for example, cardiovascular disease, dementia, and chronic kidney disease. However, the current diagnostic and therapeutic approaches lack sufficient attention to the circadian rhythmicity of blood pressure. Sleep patterns, hormone release, eating habits, digestion, body temperature, renal and cardiovascular function, and other important host functions as well as gut microbiota exhibit circadian rhythms, and influence circadian rhythms of blood pressure. Potential benefits of nonpharmacologic interventions such as meal timing, and pharmacologic chronotherapeutic interventions, such as the bedtime administration of antihypertensive medications, have recently been suggested in some studies. However, the mechanisms underlying circadian rhythm-mediated blood pressure regulation and the efficacy of chronotherapy in hypertension remain unclear. This review summarizes the results of the National Heart, Lung, and Blood Institute workshop convened on October 27 to 29, 2021 to assess knowledge gaps and research opportunities in the study of circadian rhythm of blood pressure and chronotherapy for hypertension.

The Relationship between Sleep Duration and Metabolic Syndrome Severity Scores in Emerging Adults

BACKGROUND

Research suggests sleep duration can influence metabolic systems including glucose homeostasis, blood pressure, hormone regulation, nervous system activity, and total energy expenditure (TEE), all of which are related to cardiometabolic disease risk, even in young adults. The purpose of this study was to examine the relationship between sleep duration and metabolic syndrome severity scores (MSSS) in a sample of emerging adults (18-24 y/o).

METHODS

Data were collected between 2012 and 2021 from the College Health and Nutrition Assessment Survey, an ongoing, cross-sectional study conducted at a midsized northeastern university. Anthropometric, biochemical, and clinical measures were obtained following an overnight fast and used to assess the prevalence of metabolic syndrome (MetS). MetS severity scores (MSSS) were calculated using race- and sex-specific formulas. Sleep duration was calculated from the difference in self-reported bedtime and wake time acquired through an online survey. ANCOVA was used to examine the relationship between sleep duration and MetS severity score while adjusting for covariates (age, sex, BMI, physical activity level, smoking status, alcohol consumption, and academic major).

RESULTS

In the final sample (n = 3816), MetS (≥3 criteria) was present in 3.3% of students, while 15.4% of students presented with ≥2 MetS criteria. Mean MSSS was -0.65 ± 0.56, and the reported sleep duration was 8.2 ± 1.3 h/day. MSSS was higher among low sleepers (<7 h/day) and long sleepers (>9 h/day) compared to the reference sleepers (7-8 h/day) (-0.61 ± 0.02 and -0.63 ± 0.01 vs. -0.7 ± 0.02, respectively, p < 0.01).

CONCLUSIONS

Our findings suggest short (<7 h/day) and long (>9 h/day) sleep durations raise the risk of MetS in a sample of emerging adults. Further research is needed to elucidate the impact of improving sleep habits on future disease risk.

Sleep, testosterone and cortisol balance, and ageing men

Sleep serves important biological functions, and influences health and longevity through endocrine and metabolic related systems. Sleep debt, circadian misalignment and sleep disruption from obstructive sleep apnea is widespread in modern society and accumulates with life because recovery sleep is not completely restorative. Accumulated disordered sleep throughout life impacts the ageing process and the development of age-related diseases. When epidemiological and interventional studies are considered collectively, sleep loss and lower sleep duration are associated with lower morning, afternoon and 24-h testosterone; as well as higher afternoon, but not morning or 24-h cortisol. These reciprocal changes imbalances anabolic-catabolic signaling because testosterone and cortisol are respectively the main anabolic and catabolic signals in man. Fixing testosterone-cortisol balance by means of a novel dual-hormone clamp mitigates the induction of insulin resistance by sleep restriction and provided the first proof-of-concept that the metabolic harm from sleep loss can be ameliorated by approaches that do not require sleeping more. Obstructive sleep apnea is associated with lower testosterone, even after controlling for age and obesity whereas the conclusion that continuous positive airway pressure therapy has no effect on testosterone is premature because available studies are underpowered and better-quality studies suggest otherwise. High dose testosterone therapy induces OSA, but more physiological dosing may not; and this effect may be transient or may dissipate with longer term therapy. Studies investigating the origin of the diurnal testosterone rhythm, the effect of circadian misalignment on testosterone-cortisol balance, and methods to mitigate metabolic harm, are required.

Sleep characteristics associated with nocturnal blood pressure nondipping in healthy individuals: a systematic review

OBJECTIVE

The current literature investigating nocturnal blood pressure (BP) nondipping has largely focused on clinical populations, however, conditions such as hypertension, obstructive sleep apnoea and insomnia are recognized confounding factors for BP dipping. The exact mechanisms responsible for BP nondipping remain unclear, therefore, there is a need to investigate BP nondipping in healthy individuals to better understand the underlying mechanisms. This review identifies sleep characteristics that may contribute to BP nondipping in healthy individuals. It is anticipated that an understanding of the sleep characteristics that contribute to BP nondipping may inform future sleep-related behavioral interventions to ultimately reducing the burden of cardiovascular disease.

METHODS

The PubMed, Scopus and Web of Science databases were searched for relevant, English language, peer-reviewed publications (from inception to March 2022). The search identified 550 studies. After duplicates were removed, the titles and abstracts of the remaining 306 studies were screened. Of these, 250 studies were excluded leaving 56 studies to test for eligibility. Thirty-nine studies were excluded such that 17 studies fully met the inclusion criteria for the review.

RESULTS

Findings from this review indicate that short sleep duration, more sleep fragmentation, less sleep depth and increased variability in sleep timing may be associated with BP nondipping in healthy individuals.

CONCLUSION

While there is no evidence-based approach for the treatment of nocturnal BP nondipping, it seems promising that addressing one's sleep health may be an important starting point to reduce the prevalence of BP nondipping and perhaps the progression to cardiovascular disease.

The Oscillometric Pulse Wave Analysis Is Useful in Evaluating the Arterial Stiffness of Obese Children with Relevant Cardiometabolic Risks

Early detection of all complications of childhood obesity is imperative in order to minimize effects. Obesity causes vascular disruptions, including early increased arterial stiffness and high blood pressure. This study’s aim is to assess the reliability of pulse wave analysis (PWA) in obese children and how additional risk factors influence the evaluated parameters. We analyzed 55 children aged 6–18 years old by measuring their pulse wave velocity (PWV), augmentation index (AIx), peripheral blood pressure (SBP, DBP), heart rate, central blood pressure (cSBP, cDBP) and central pulse pressure (cPP). We used the oscillometric IEM Mobil-O-Graph and performed a single-point brachial measurement. The subjects were divided into two groups: obese (n = 30) and normal-weight (n = 25) and were clinically and anamnestically assessed. BMI and waist circumference are significantly correlated to higher values for PWV, SBP, DBP, cSBP, and cDBP. Weight significantly predicts PWV, SBP, DBP and cPP. The risk factors that significantly influence the PWA and BP values are: a cardiometabolically risky pregnancy (higher PWV, AIx, SBP), active and passive smoking (higher PWV, SBP, cSBP, cDBP), sleep deprivation (higher PWV, SBP, cSBP) and sedentariness (higher PWV, AIx, peripheral and central BP). We conclude that obese children with specific additional cardiometabolic risk factors present increased arterial stiffness and higher blood pressure values.

The Association Between Habitual Sleep Duration and Blood Pressure Control in United States (US) Adults with Hypertension

Purpose

This study examined the relationship between habitual sleep duration and blood pressure (BP) control in adults with hypertension.

Methods

This cross-sectional study used data of 5163 adults with hypertension obtained from the 2015–2018 National Health and Nutrition Examination Survey (NHANES). Multivariable logistic regression was used to analyze the association between habitual sleep duration and BP control. Habitual sleep duration was self-reported and defined as the amount of sleep usually obtained in a night or main sleep period during weekdays or workdays. It was categorized as <6, 6 - <7, 7–9, and >9 hours. BP control was defined as average systolic BP <130mmHg and diastolic BP <80mmHg.

Results

Results from the fully adjusted models show that among all adults with hypertension, habitual sleep duration of <6 hours night/main sleep period was associated with reduced odds of BP control (OR = 0.53, 95% CI: 0ss.37–0.76, P = 0.001) when compared to 7–9 hours. In the subpopulation of adults who were on antihypertensive medication, those with a sleep duration of <6 hours had lower odds of BP control than those with a sleep duration of 7–9 hours (OR = 0.53, 95% CI: 0.36–0.77, P = 0.002). No significant differences were noted in all adults with hypertension and in the subpopulation of those on antihypertensive medication in BP control between the reference sleep duration group (7–9 hours) and the 6 - <7 or >9 hours groups. There were no significant differences across age groups or gender in the relationship between habitual sleep duration and BP control.

Conclusion

Sleep duration of <6 hours is associated with reduced odds of hypertension control. These significant findings indicate that interventions to support adequate habitual sleep duration may be a promising addition to the current hypertension management guidelines.

Association between Sleep Duration and Hypertension among Adults in Southwest China

Objective:

This study aimed to evaluate the association between sleep duration and hypertension among adults in southwest China.

Methods:

Baseline variables were collected from a representative sample of 20,053 adults aged 23–98 years in southwest China who received physical examinations from January 2019 to December 2020. All participants were categorized into either a hypertension group or a non-hypertension group. Sleep duration was classified as short (<6 h/day), normal (6–8 h/day),or long (>8 h/day). Baseline variables were compared between individuals with and without hypertension by rank-sum tests for two independent samples or χ² tests for nonparametric data. Multivariate logistic regression analysis was performed to evaluate the association between sleep duration and hypertension.

Results:

The overall incidence of hypertension was 51.2%. Unadjusted analysis showed that the risk of hypertension was higher in individuals with short (<6h/day) or long (>8h/day) sleep durations compared with those with a normal (6–8 h/day) sleep duration. The risk of hypertension was significantly increased by 30.1% in participants with a long (>8h/day) sleep duration compared with those with a normal (6–8h/day) sleep duration (OR = 1.301, P < 0.010, 95%CI = 1.149–1.475). The risk of hypertension was also increased by 1.1% in participants with a short (<6h/day) sleep duration compared with participants with a normal (6–8h/day) sleep duration, but the difference was not significant (OR = 1.011, P = 0.849, 95%CI = 0.905–1.129). After fully adjusting for confounding factors (model 4), the risk of hypertension was increased significantly (by 25%) in individuals with a short (<6h/day) sleep duration (OR = 1.25, P = 0.02, 95%CI = 1.036–1.508) but not in those with a long (>8h/day) sleep duration (17.5% increase) compared with participants with a normal (6–8h/day) sleep duration (OR = 1.175, P = 0.144, 95%CI = 0.946–1.460).

Conclusion:

The results of this study indicate that a short (<6h/day) sleep duration is related to an increased risk of hypertension, suggesting that sleep helps to protect against hypertension.

Effects of curtailed sleep on cardiac stress biomarkers following high-intensity exercise

Objective

Physical exercise—especially at high intensity—is known to impose cardiac stress, as mirrored by, e.g., increased blood levels of cardiac stress biomarkers such as cardiac Troponin T (cTnT) and NT-proBNP. We examined healthy young participants to determine whether a few nights of short sleep duration alter the effects of acute exercise on these blood biomarkers.

Methods

Sixteen men participated in a randomized order in a crossover design, comprising three consecutive nights of a) normal sleep duration (NS, 8.5 h of sleep/night) and b) sleep restriction (SR, 4.25 h of sleep/night). Blood was repeatedly sampled for determination of NT-proBNP and cTnT serum levels before and after a high-intensity exercise protocol (i.e., 75% VO₂^maxReserve cycling on an ergometer).

Results

Under pre-exercise sedentary conditions, blood levels of cTnT and NT-proBNP did not significantly differ between the sleep conditions (P > 0.10). However, in response to exercise, the surge of circulating cTnT was significantly greater following SR than NS (+37–38% at 120–240 min post-exercise, P ≤ 0.05). While blood levels of NT-proBNP rose significantly in response to exercise, they did not differ between the sleep conditions.

Conclusion

Recurrent sleep restriction may increase the cardiac stress response to acute high-intensity exercise in healthy young individuals. However, our findings must be further confirmed in women, older subjects and in patients with a history of heart disease.

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Chronic sleep curtailment increases the risk of cardiovascular disease.

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Here, we examined whether exercise-induced cardiac strain in healthy young adults is altered by sleep curtailment.

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Blood levels of the cardiac stress marker troponin were higher after exercise under conditions of recurrent sleep restriction.

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Sleep restriction may increase exercise-induced cardiac strain in adults.

Challenges and Opportunities for Applying Wearable Technology to Sleep

Wearable technology has a history in sleep research dating back to the 1970s. Because modern wearable technology is relatively cheap and widely used by the general population, this represents an opportunity to leverage wearable devices to advance sleep medicine and research. However, there is a lack of published validation studies designed to quantify device performance against accepted gold standards, especially across different populations. Recommendations for conducting performance assessments and using wearable devices are now published with the goal of standardizing wearable device implementation and advancing the field.

Actigraphy-derived rest-activity rhythms are associated with nocturnal blood pressure in young women

INTRODUCTION

Misalignment between lifestyle behaviors and endogenous circadian rhythms is associated with elevated nocturnal blood pressure (BP) in experimental studies; however, less is known about free-living (i.e. nonlaboratory) circadian disruption and nocturnal BP. Additionally, sex-specific cardiovascular implications of circadian disruption are unclear.

OBJECTIVE

To examine the associations between rest--activity rhythms (RAR), a field-based estimate of circadian disruption, and nocturnal BP characteristics in male and female young adults.

METHODS

Fifty participants (20 ± 1 years; 20 men/30 women) underwent 24-h ambulatory BP monitoring following 14 days of wrist actigraphy. RAR variables of interdaily stability (day-to-day consistency in RAR), intradaily variability (within-day fragmentation of RAR), and relative amplitude (difference between peak vs. trough activity) were derived from actigraphy. Multivariable regression models of mean nocturnal SBP, DBP, and SBP dipping were generated to test main associations with RAR variables, and sex × RAR interactions. Daytime BP, race, BMI, physical activity, sleep duration, alcohol, caffeine, and sodium intake were considered as covariates.

RESULTS

In the full sample, no main associations between RAR and nocturnal BP characteristics were found. Sex interacted with RAR such that in women, higher interdaily stability (β = -5.39, 95% CI = -10.04 to -0.73, P = 0.024) and relative amplitude (β = -4.78, 95% CI = -9.22 to -0.34, P = 0.036) were both associated with lower nocturnal SBP. Sex-stratified multivariable models of nocturnal BP also revealed associations between interdaily stability and relative amplitude with SBP dipping in women (all P ≤ 0.01). No associations were apparent in men.

CONCLUSION

Consistent and high-amplitude RAR are favorably associated with nocturnal BP characteristics in young female adults.

Effects of Experimental Sleep Restriction on Ambulatory and Sleep Blood Pressure in Healthy Young Adults: A Randomized Crossover Study

[Figure: see text].

Macro- and microvascular reactivity during repetitive exposure to shortened sleep: sex differences

Epidemiological studies have reported strong association between sleep loss and hypertension with unknown mechanisms. This study investigated macrovascular and microcirculation changes and inflammatory markers during repetitive sleep restriction. Sex differences were also explored. Forty-five participants completed a 22-day in-hospital protocol. Participants were assigned to, (1) eight-hour sleep per night (control), or (2) sleep restriction (SR) condition: participants slept from 0300 to 0700 h for three nights followed by a recovery night of 8-h sleep, repeated four times. Macrocirculation assessed by flow mediated dilation (FMD) and microcirculation reactivity tests were performed at baseline, last day of each experimental block and during recovery at the end. Cell adhesion molecules and inflammatory marker levels were measured in blood samples. No duration of deprivation (SR block) by condition interaction effects were found for FMD, microcirculation, norepinephrine, cell adhesion molecules, IL-6 or IL-8. However, when men and women were analyzed separately, there was a statistical trend (p = 0.08) for increased IL-6 across SR blocks in women, but not in men. Interestingly, men showed a significant progressive (dose dependent) increase in skin vasodilatation (p = 0.02). A novel and unexpected finding was that during the recovery period, men that had been exposed to repeated SR blocks had elevated IL-8 and decreased norepinephrine. Macrocirculation, microcirculation, cell adhesion molecules, and markers of inflammation appeared to be resistant to this model of short-term repetitive exposures to the blocks of shortened sleep in healthy sleepers. However, men and women responded differently, with women showing mild inflammatory response and men showing more vascular system sensitivity to the repetitive SR.

Napping on the night shift and its impact on blood pressure and heart rate variability among emergency medical services workers: study protocol for a randomized crossover trial

BACKGROUND

There is an emerging body of evidence that links exposure to shift work to cardiovascular disease (CVD). The risk of coronary events, such as myocardial infarction, is greater among night shift workers compared to day workers. There is reason to believe that repeated exposure to shift work, especially night shift work, creates alterations in normal circadian patterns of blood pressure (BP) and heart rate variability (HRV) and that these alterations contribute to increased risk of CVD. Recent data suggest that allowing shift workers to nap during night shifts may help to normalize BP and HRV patterns and, over time, reduce the risk of CVD. The risk of CVD related to shift work is elevated for emergency medical services (EMS) shift workers due in part to long-duration shifts, frequent use of night shifts, and a high prevalence of multiple jobs.

METHODS

We will use a randomized crossover trial study design with three study conditions. The targeted population is comprised of EMS clinician shift workers, and our goal enrollment is 35 total participants with an estimated 10 of the 35 enrolled not completing the study protocol or classified as lost to attrition. All three conditions will involve continuous monitoring over 72 h and will begin with a 36-h at-home period, followed by 24 total hours in the lab (including a 12-h simulated night shift), ending with 12 h at home. The key difference between the three conditions is the intra-shift nap. Condition 1 will involve a simulated 12-h night shift with total sleep deprivation. Condition 2 will involve a simulated 12-h night shift and a 30-min nap opportunity. Condition 3 will involve a simulated 12-h night shift with a 2-h nap opportunity. Our primary outcomes of interest include blunted BP dipping and reduced HRV as measured by the standard deviation of the inter-beat intervals of normal sinus beats. Non-dipping status will be defined as sleep hours BP dip of less than 10%.

DISCUSSION

Our study will address two indicators of cardiovascular health and determine if shorter or longer duration naps during night shifts have a clinically meaningful impact.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04469803 . Registered on 9 July 2020.

Effect of Sleep Disturbances on Blood Pressure

This review summarizes recent literature addressing the association of short sleep duration, shift work, and obstructive sleep apnea with hypertension risk, blood pressure (BP) levels, and 24-hour ambulatory BP. Observational studies demonstrate that subjectively assessed short sleep increases hypertension risk, though conflicting results are observed in studies of objectively assessed short sleep. Intervention studies demonstrate that mild and severe sleep restriction are associated with higher BP. Rotating and night shift work are associated with hypertension as shift work may exacerbate the detrimental impact of short sleep on BP. Further, studies demonstrate that shift work may increase nighttime BP and reduce BP control in patients with hypertension. Finally, moderate to severe obstructive sleep apnea is associated with hypertension, particularly resistant hypertension. Obstructive sleep apnea is also associated with abnormal 24-hour ambulatory BP profiles, including higher daytime and nighttime BP, nondipping BP, and a higher morning surge. Continuous positive airway pressure treatment may lower BP and improve BP dipping. In conclusion, efforts should be made to educate patients and health care providers about the importance of identifying and treating sleep disturbances for hypertension prevention and management. Empirically supported sleep health interventions represent a critical next step to advance this research area and establish causality.

Go Red for Women Strategically Focused Research Network: Summary of Findings and Network Outcomes

The Go Red for Women movement was initiated by the American Heart Association (AHA) in the early 2000s to raise awareness concerning cardiovascular disease (CVD) risk in women. In 2016, the AHA funded 5 research centers across the United States to advance our knowledge of the risks and presentation of CVD that are specific to women. This report highlights the findings of the centers, showing how insufficient sleep, sedentariness, and pregnancy-related complications may increase CVD risk in women, as well as presentation and factors associated with myocardial infarction with nonobstructive coronary arteries and heart failure with preserved ejection fraction in women. These projects were augmented by collaborative ancillary studies assessing the relationships between various lifestyle behaviors, including nightly fasting duration, mindfulness, and behavioral and anthropometric risk factors and CVD risk, as well as metabolomic profiling of heart failure with preserved ejection fraction in women. The Go Red for Women Strategically Focused Research Network enhanced the evidence base related to heart disease in women, promoting awareness of the female-specific factors that influence CVD.

Dissociation of Subjective and Objective Alertness During Prolonged Wakefulness

BACKGROUND

Although the deterioration of subjective and objective alertness during prolonged wakefulness has been investigated rigorously, whether perceived sleepiness and fatigue are consistent with actual decrements in behavioral performance in the time course is still disputed. The present study examined the dissociation between decrements of subjective alertness and performance deficits during prolonged wakefulness of one night and explored the relationship between body temperature and the impairments of subjective and objective alertness.

PARTICIPANTS AND METHODS

Thirty-eight participants (27 females; age: 21.76 ± 2.37 years old) underwent prolonged wakefulness for one night at habitual bedtime (0:00-6:00 am). Participants completed a 10-min PVT to assess objective alertness, fatigue, and sleepiness ratings to assess subjective alertness every 2 hours, and body temperature was measured every hour during scheduled wakefulness.

RESULTS

Subjective alertness reflected a linear decline with time, but the magnitudes of objective performance deterioration increased significantly between 4:00 and 6:00 am. The increasing magnitudes of performance deficits were associated with the change of body temperature between 4:00 and 6:00 am.

CONCLUSION

These results indicate that the perceived degree of decline in alertness is temporally dissociated with the actual decline in objective vigilance with increased duration of wakefulness. The dissociation of magnitudes of subjective and objective alertness decrements mainly occurs between 4:00 and 6:00 am, and the changes of performance deficits have a relationship with body temperature.

Identifying patterns of diurnal blood pressure variation among ELSA-Brasil participants

Ambulatory blood pressure monitoring (ABPM) is the gold standard method for the diagnosis of hypertension. ABPM provides a set of repeated measurements for blood pressure (BP), usually over 24 h. Traditional approaches characterize diurnal BP variation by single ABPM parameters such as average and standard deviation, regardless of the temporal nature of the data. In this way, information about the pattern of diurnal BP variation and relationship between parameters is lost. The objective of this study was to identify and characterize daily BP patterns considering the set of repeated measures from 24-h ABPM. A total of 859 adult participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) performed a 24-h ABPM record. Hypertension, sex, age, race/color, education, marital status, smoking, alcohol, physical activity, and BMI were the covariables analyzed. Techniques for longitudinal clustering, multinomial models, and models with mixed effects were used. Three daily BP patterns were identified. Daily BP patterns with high BP presented higher standard deviation and morning surge and lower nocturnal dipping. They showed greater systolic BP variability and faster rise than fall in diastolic BP during sleep. Hypertensive, "pardos," and men had greater odds to present these patterns. Daily BP patterns with high BP presented the worst profile concerning ABPM parameters associated with cardiovascular risk. The daily BP patterns identified contribute to the characterization of diurnal BP variation.

Should public safety shift workers be allowed to nap while on duty?

Fatigue and sleep deficiency among public safety personnel are threats to wellness, public and personal safety, and workforce retention. Napping strategies may reduce work-related fatigue, improve safety and health, yet in some public safety organizations it is discouraged or prohibited. Our aim with this commentary is to define intra-shift napping, summarize arguments for and against it, and to outline potential applications of this important fatigue mitigation strategy supported by evidence. We focus our discussion on emergency medical services (EMS); a key component of the public safety system, which is comprised of police, fire, and EMS. The personnel who work in EMS stand to benefit from intra-shift napping due to frequent use of extended duration shifts, a high prevalence of personnel working multiple jobs, and evidence showing that greater than half of EMS personnel report severe fatigue, poor sleep quality, inadequate inter-shift recovery, and excessive daytime sleepiness. The benefits of intra-shift napping include decreased sleepiness and fatigue, improved recovery between shifts, decreased anxiety, and reduced feelings of burnout. Intra-shift napping also mitigates alterations in clinician blood pressure associated with disturbed sleep and shift work. The negative consequences of napping include negative public perception, acute performance deficits stemming from sleep inertia, and the potential costs associated with reduced performance. While there are valid arguments against intra-shift napping, we believe that the available scientific evidence favors it as a key component of fatigue mitigation and workplace wellness. We further believe that these arguments extend beyond EMS to all sectors of public safety.

Association between circadian disruption and diseases: A narrative review

Circadian rhythms play an important role in a wide range of human physiology and pathology. Individuals increasingly experience situations such as night-shift work schedules, likely leading to circadian disruption. Recent studies have also demonstrated that patients with other diseases often show symptoms of circadian disruption as manifested by the sleep-wake cycle and other biological rhythms. Circadian disruption often results in changes to the phase, period, and amplitude of the sleep-wake cycle, melatonin rhythm, and core body temperature. Several cardiometabolic, psychiatric, and neurodegenerative diseases are closely related to circadian disruption. Several interventions are also available, including phototherapy, exogenous melatonin, and exercise. The cumulative findings suggest that circadian disruption can increase risk for some cardiometabolic diseases. Circadian disruption also acts as a concomitant symptom of several psychiatric and neurodegenerative diseases. More attention should be paid to evaluating the impact of circadian disruption on these related diseases, as well as the benefits of the mitigation interventions for both circadian disruption and related diseases.

Caloric and Macronutrient Intake and Meal Timing Responses to Repeated Sleep Restriction Exposures Separated by Varying Intervening Recovery Nights in Healthy Adults

Sleep restriction (SR) reliably increases caloric intake. It remains unknown whether such intake cumulatively increases with repeated SR exposures and is impacted by the number of intervening recovery sleep opportunities. Healthy adults (33.9 ± 8.9y; 17 women, Body Mass Index: 24.8 ± 3.6) participated in a laboratory protocol. N = 35 participants experienced two baseline nights (10 h time-in-bed (TIB)/night; 22:00–08:00) followed by 10 SR nights (4 h TIB/night; 04:00–08:00), which were divided into two exposures of five nights each and separated by one (n = 13), three (n = 12), or five (n = 10) recovery nights (12 h TIB/night; 22:00–10:00). Control participants (n = 10) were permitted 10 h TIB (22:00–08:00) on all nights. Food and drink consumption were ad libitum and recorded daily. Compared to baseline, sleep-restricted participants increased daily caloric (+527 kcal) and saturated fat (+7 g) intake and decreased protein (−1.2% kcal) intake during both SR exposures; however, intake did not differ between exposures or recovery conditions. Similarly, although sleep-restricted participants exhibited substantial late-night caloric intake (671 kcal), such intake did not differ between exposures or recovery conditions. By contrast, control participants showed no changes in caloric intake across days. We found consistent caloric and macronutrient intake increases during two SR exposures despite varying intervening recovery nights. Thus, energy intake outcomes do not cumulatively increase with repeated restriction and are unaffected by recovery opportunities.

Ambulatory blood pressure monitoring among emergency medical services night shift workers

OBJECTIVES

Higher 24-hour blood pressure (BP) and blunted BP dipping during sleep and night-time hours are associated with adverse health outcomes. Night shift work may affect 24-hour BP and dipping patterns, but empirical data in emergency medical services (EMS) clinician shift workers are sparse. We implemented ambulatory blood pressure monitoring (ABPM) in EMS workers to characterise BP during night shift work versus a non-workday, and sleep versus wake.

METHODS

Participants worked night shifts. Hourly ABPM and wrist actigraphy (to measure sleep) were collected during two 24-hour periods, one scheduled night shift and one non-workday. Blunted BP dipping was defined as a BP decrease of <10%.

RESULTS

Of 56 participants, 53 (53.6% female, mean age 26.5 (SD 7.5) years) completed the study. During daytime sleep on a workday, 49.1% of participants had blunted systolic BP (SBP) or diastolic BP (DBP) dipping. During night-time sleep on a non-workday, 25% had blunted SBP dipping and 3.9% blunted DBP dipping. Blunted SBP or DBP dipping occurred among all participants who did not nap during the night shift or who napped <60 min. Blunted SBP dipping occurred in only 14.3% of participants who napped 60-120 min.

CONCLUSIONS

During night shift work, the BP dipping of EMS shift workers is blunted; however, most who nap for 60 min or longer experience a healthy dip in BP. The potential health consequences of these observations in EMS clinicians warrant further study.

Lipid peroxidation in the descending thoracic aorta of rats deprived of REM sleep using the inverted flowerpot technique

NEW FINDINGS

What is the central question of this study? Deprivation of rapid eye movement (REM) sleep is associated with increased oxidative stress, but its effects on the blood vessels are poorly documented. We investigated whether REM sleep deprivation induces oxidative stress and causes lipid peroxidation in the aorta. What is the main finding and its important? We demonstrate that REM sleep deprivation induces oxidative stress and mediates lipid peroxidation in the aorta. This can cause endothelial changes and increased blood pressure. These findings will contribute to the growing body of literature on the mechanism underlying the effects of sleep deprivation on cardiovascular disease.

ABSTRACT

Oxidative stress-mediated lipid peroxidation is a known cause of endothelial injury or dysfunction. Deprivation of rapid eye movement (REM) sleep is associated with oxidative stress. To date, the pathogenesis of increased blood pressure after sleep deprivation remains poorly understood, particularly in the REM sleep phase. Our aim was to investigate the effects of REM sleep deprivation on blood vessels in the REM sleep-deprived rat model. Twenty-eight male Sprague-Dawley rats were divided into four equal groups: free-moving control rats, rats deprived of REM sleep for 72 h (REMsd), tank control rats and 72 h sleep-recovered rats after 72 h of REM sleep deprivation. The rats were deprived of REM sleep using the inverted flowerpot technique. Food consumption, body weight gain and systolic blood pressure were monitored. At the end of the experiment, the descending thoracic aorta was isolated for the measurement of oxidative stress markers. Despite a significant increase in food consumption in the REMsd group compared with the other groups, there was a significant reduction in body weight gain. Systolic blood pressure also showed a significant increase in the REMsd group compared with the other groups. Superoxide dismutase activity was significantly lower and malondialdehyde concentrations significantly higher in the REMsd group compared with the other groups. Increased levels of malondialdehyde are suggestive of lipid peroxidation in the blood vessels, and oxidative stress may be attributed to the initiation of the process. The changes after REM sleep deprivation revert during sleep recovery. In conclusion, the findings of the present study provide convincing evidence that REM sleep deprivation induced lipid peroxidation, leading to endothelial damage.

Sleep quantity and quality and cardiometabolic risk factors in Indigenous Australians

Poor sleep is associated with increased risk of cardiovascular disease (CVD). Indigenous Australians have 1.3 times higher risk of CVD compared to non-indigenous Australians. However, there are limited data describing sleep problems and cardiometabolic risk in this population. This study aimed to investigate sleep quantity and quality in indigenous Australians and assess its association with cardiometabolic risk. Two hundred and forty-five indigenous Australians aged > 18 years were recruited via convenience sampling from communities in the Northern Territory and Queensland. Sleep quantity and quality was assessed subjectively with questionnaires including the Epworth Sleepiness Scale. In a sub-population (n = 46), objective sleep assessment was performed over three nights of actigraphy. Cardiometabolic risk measures included glycated haemoglobin, lipids, anthropometric measurements and sitting blood pressure. Sleep duration measured subjectively and objectively averaged 7.5 ± 2.0 hr/night; however, over one-third of participants (self-report 35%; actigraphy 39%) obtained < 7 hr/night. Overall, more than a third of participants experienced poor-quality sleep, with 27% reporting severe daytime sleepiness (ESS score > 10) and a high number of objectively measured awakenings/night (6 ± 4). Short sleep duration (<6 hr/night) measured both subjectively and objectively was an independent predictor of diastolic (β = 5.37, p = .038) and systolic blood pressure (β = 14.30, p = .048). More objectively measured night-time awakenings were associated with increased glycated haemoglobin levels (β = 0.07, p = .020) and greater sleep fragmentation was associated with lower high-density lipoprotein levels (β = -0.01, p = .025). A large proportion of indigenous Australians experienced short sleep durations and had significant sleep disruption. Poor sleep quantity and quality may contribute to heightened cardiometabolic risk in this population.

Mild sleep restriction increases 24-hour ambulatory blood pressure in premenopausal women with no indication of mediation by psychological effects

BACKGROUND

Studies assessing the impact of sleep restriction (SR) on blood pressure (BP) are limited by short study length, extreme SR (<4 hours a night), and lack of attention to psychological distress as a possible mediator.

METHODS

A community-based cohort was assembled with 237 women (age 34.1 ± 13.5 years; body mass index 25.4 ± 5.4 kg/m²), and a randomized, crossover, intervention study was conducted in 41 women (24 completed: age 30.2 ± 6.5 years; body mass index 24.3 ± 2.8 kg/m²) to determine the causal effect of SR on BP. Sleep was maintained as usual (HS) or reduced by 1.5 hours a night (SR) for 6 weeks. In the cohort, associations between sleep and psychosocial factors were evaluated using multivariable models adjusted for demographic and clinical confounders. In the intervention study, in-office BP was measured weekly; ambulatory BP was measured at end point. Psychological factors were assessed at baseline and end point. Mixed-model analyses with total sleep time (TST, main predictor), week and fraction of time spent in physical activity (covariates), and subject (random effect) were performed.

RESULTS

Among the community cohort, higher perceived stress, stressful events and distress, and lower resilience were associated with shorter sleep, worse sleep quality, and greater insomnia symptoms (P < .05). In the intervention, systolic BP increased as TST decreased (TST × week interaction, [coefficient ± standard error] -0.0097 ± 0.0046, P = .036). Wake ambulatory diastolic blood pressure (-0.059 ± 0.022, P = .021) and mean arterial pressure (-0.067 ± 0.023, P = .018) were higher after SR versus HS. Psychological distress variables were not affected by TST and did not mediate the effects of SR on BP.

CONCLUSIONS

These results suggest that SR influences CVD risk in women via mechanisms independent of psychological stressors.

Sleep and cardiovascular disease: Emerging opportunities for psychology

Sleep disturbances and disorders have been implicated in cardiovascular morbidity and mortality. Converging evidence suggests that psychosocial factors that confer risk or resilience to cardiovascular disease (CVD) are also related to sleep. Profound differences in sleep among racial/ethnic minorities compared with non-Hispanic Whites in the United States suggest that sleep, and its interplay with psychosocial factors, may contribute to observed disparities in CVD and in health and functioning more broadly. Less understood is the extent to which sleep and psychosocial factors interact to influence the pathophysiology and clinical course of CVD. This article reviews observational and experimental evidence linking short sleep duration and insomnia, both modifiable sleep disturbances, to CVD, including key physiological mechanisms. Also reviewed is evidence of significant interrelationships among sleep, race/ethnicity, and psychosocial factors known to confer risk or resilience to CVD, including depression, psychological stress, and close interpersonal relationships. It is proposed that a transdisciplinary research framework that integrates knowledge, methods, and measures from the fields of psychology and sleep research may be used to catalyze advances in the prevention and treatment of CVD. Also discussed are promising new directions, expected challenges, and the importance of training in transdisciplinary science and research approaches. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Sleep debt and prevalence of proteinuria in subjects with short sleep duration on weekdays: a cross-sectional study

STUDY OBJECTIVE

Short sleep duration is a risk factor of chronic kidney disease, along with cardiovascular diseases and all-cause mortality. Several studies reported that many people sleep longer on weekends than on weekdays, suggesting that they should be compensated for their sleep debt on weekdays on the weekends. Few studies have reported the clinical impact of sleep debt on the kidney.

METHODS

This cross-sectional study included 5799 employees of Osaka University who visited its Health Care Center for their annual health examinations and answered ≤ 6 h of sleep duration on weekdays. The independent variable was the sleep debt index defined as a gap in self-reported sleep duration (≤ 5, 5-6, 6-7, 7-8, 8-9, and ≥ 9 h) between weekdays and weekends, which was categorized into ≤ 0, + 1, + 2, + 3 and ≥+4. An association between the sleep debt index and a prevalence of proteinuria defined as dipstick proteinuria of ≥ 1 + was assessed using logistic regression models adjusting for clinically relevant factors.

RESULTS

More than four-fifths of the subjects had a positive sleep debt index (≤ 0, + 1, + 2, + 3, and ≥+4 recorded for 19%, 36%, 28%, 11%, and 6%, respectively). The multivariable-adjusted logistic regression models showed the sleep debt index ≥ 3 + was significantly associated with the prevalence of proteinuria (sleep debt index ≤ 0, adjusted odds ratio 1.13 [0.77, 1.65]; + 1, 1.00 [reference]; + 2, 1.29 [0.93, 1.79]; + 3, 1.54 [1.02, 2.33]; ≥ + 4, 1.87 [1.15, 3.05]).

CONCLUSIONS

Sleep debt was associated with the prevalence of proteinuria in a dose-dependent manner.

Sleep Restriction Effects on BP: Systematic Review & Meta-analysis of RCTs

This systematic review and meta-analysis aimed to examine the effect of sleep restriction on blood pressure (BP) among healthy adults. Randomized controlled trials (RCTs) using partial sleep deprivation were included. The pooled effect size was calculated by the inverse variance method, and forest plot was used. Six studies were included (n = 10-43). Only one study obtained continuous BP readings. Overall, sleep restriction did not result in significant changes in systolic blood pressure (SBP) or diastolic blood pressure (DBP) and heart rate (HR). The respective weighted mean difference (MD) was 1.0 mmHg (95%CI, -2.3-4.2; p = 0.57), -0.4 mmHg (95%CI, -3.2-2.4; p = 0.80), and 2.0 bpm (95%CI, -2.2-6.2; p = 0.34). There is preliminary evidence suggesting that sleep restriction might affect sympathetic/parasympathetic modulation of cardiac autonomy and the inflammatory system. In this review, we did not find significant effects of sleep restriction on BP or HR measured by cross-sectional methods. More studies are warranted to confirm these findings by using continuous monitoring.

Sleep Duration and Blood Pressure: Recent Advances and Future Directions

PURPOSE OF REVIEW

This review discusses the recent literature on subjectively and objectively assessed sleep duration in relation to hypertension risk and out-of-clinic blood pressure (BP) measures and highlights critical areas for future research.

RECENT FINDINGS

Sleep duration, particularly short sleep, may influence BP through disturbed autonomic balance, hormonal imbalances, increased adiposity and metabolic dysfunction, and disrupted circadian rhythms. Observational studies indicate that short and long sleep are associated with hypertension risk, reduced nocturnal dipping, and elevated morning BP, but evidence is stronger for short sleep. Experimental sleep restriction increases BP, while sleep extension may lower BP in prehypertensive individuals. Women and racial/ethnic minorities are more prone to the detrimental effects of short sleep on BP. Additional studies are warranted to clarify the association of objectively assessed sleep with BP level and diurnal pattern and to determine the sex- and race-specific effects of sleep restriction and extension on BP.

Reciprocal Roles of Sleep and Diet in Cardiovascular Health: a Review of Recent Evidence and a Potential Mechanism

PURPOSE OF REVIEW

This review investigates the potential bi-directional relation between sleep and diet in considering their contribution to cardiovascular health. We further explore the involvement of the gut microbiome in the relationships between poor sleep and dietary intakes and increased cardiovascular disease (CVD) risk.

RECENT FINDINGS

There is strong evidence that sleep restriction leads to unhealthy food choices and increased energy intake. The diet may impact sleep, as well. Epidemiological studies show that higher adherence to a Mediterranean dietary pattern predicts healthier sleep. One factor that could underlie these relationships is the gut microbiome. Although data are mixed, there is some evidence that sleep restriction can influence the composition of the gut microbiome in humans. Similarly, Mediterranean diets and other plant-rich diets are related to increased diversity of the microbiota. At present, few studies have investigated the influence of the microbiome on sleep; however, limited evidence from epidemiological and intervention studies suggest that the composition of the microbiome may relate to sleep quality. More research is needed to better understand the role of the microbiome in the multi-directional relationship between sleep, diet, and CVD. There is growing evidence of a bi-directional relationship between sleep and the diet, which could act in concert to influence CVD risk. Diets such as the Mediterranean diet, comprised of high intakes of fruits, vegetables, and other plant-based foods, may promote healthy sleep and beneficial gut microflora. The gut microbiome may then underlie the relation between diet, sleep, and CVD risk.

Heart rate variability rebound following exposure to persistent and repetitive sleep restriction

While it is well established that slow-wave sleep electroencephalography (EEG) rebounds following sleep deprivation, very little research has investigated autonomic nervous system recovery. We examined heart rate variability (HRV) and cardiovagal baroreflex sensitivity (BRS) during four blocks of repetitive sleep restriction and sequential nights of recovery sleep. Twenty-one healthy participants completed the 22-day in-hospital protocol. Following three nights of 8-hr sleep, they were assigned to a repetitive sleep restriction condition. Participants had two additional 8-hr recovery sleep periods at the end of the protocol. Sleep EEG, HRV, and BRS were compared for the baseline, the four blocks of sleep restriction, and the second (R2) and third (R3) nocturnal recovery sleep periods following the last sleep restriction block. Within the first hour of each sleep period, vagal activation, as indexed by increase in high frequency (HF; HRV spectrum analysis), showed a rapid increase, reaching its 24-hr peak. HF was more pronounced (rebound) in R2 than during baseline (p < 0.001). The BRS increased within the first hour of sleep and was higher across all sleep restriction blocks and recovery nights (p = 0.039). Rebound rapid eye movement sleep was observed during both R2 and R3 (p = 0.004), whereas slow-wave sleep did not differ between baseline and recovery nights (p > 0.05). Our results indicate that the restoration of autonomic homeostasis requires a time course that includes at least three nights, following an exposure to multiple nights of sleep curtailed to about half the normal nightly amount.

Objective but Not Subjective Short Sleep Duration Is Associated With Hypertension in Obstructive Sleep Apnea

Extremes of sleep duration and obstructive sleep apnea (OSA) are both associated with hypertension. We aimed to explore whether sleep duration modifies the relationship between OSA and prevalent hypertension, using both objective and subjective measures of total sleep duration. A total of 7107 OSA patients and 1118 primary snorers were included in the study. Hypertension was defined based either on direct blood pressure measures or on diagnosis by a physician. Objective sleep duration was derived by polysomnography and subjective sleep duration was self-reported. Logistic regression models were used to estimate the associations between objective/subjective sleep duration and hypertension prevalence in OSA and primary snorers. Compared with primary snorers, OSA combined with objective sleep duration of 5 to 6 hours increased the odds of hypertension by 45% (odds ratio, 1.45; 95% confidence interval, 1.14-1.84), whereas OSA combined with objective sleep duration <5 hours further increased the odds of hypertension by 80% (odds ratio, 1.80; 95% confidence interval, 1.33-2.42). These results were independent of major confounding factors frequently associated with OSA or hypertension. In stratified analysis by sleep duration, risk of hypertension in those with extremely short sleep (<5 hours) was not significantly different between OSA and primary snorers, whereas odds were significant for OSA in the other 4 sleep duration strata (5-6, 6-7, 7-8, and >8 hours). No significance was evident using subjective sleep duration. We conclude that objective short sleep duration is associated with hypertension in OSA patients. Extremely short sleep duration in itself may actually be even more detrimental than OSA in terms of hypertension risk.

Sleep Duration and Hypertension: Analysis of > 700,000 Adults by Age and Sex

STUDY OBJECTIVES

The objective of this study was to evaluate the cross-sectional relationship between sleep duration and hypertension in a large, nationally-representative dataset that spans 10 years. This analysis may provide detailed information with high resolution about how sleep duration is related to hypertension and how this differs by demographic group.

METHODS

Data were aggregated from the 2013 Behavioral Risk Factor Surveillance System (n = 433,386) and the combined 2007-2016 National Health Interview Surveys (n = 295,331). These data were collected by the Centers for Disease Control and Prevention from nationally-representative samples. Surveys were combined, and survey-specific weights were used in all analyses. Sleep duration was assessed with the item, "On average, how many hours of sleep do you get in a 24-hour period?" in both surveys. Hypertension was assessed as self-reported history. Covariates were assessed identically in both datasets and included, age (in 5-year groupings), sex, race/ethnicity, and employment status.

RESULTS

In adjusted analyses, compared to 7 hours, increased risk of hypertension was seen among those sleeping ≤ 4 hours (odds ratio [OR] = 1.86, P < .0005), 5 hours (OR = 1.56, P < .0005), 6 hours (OR = 1.27, P < .0005), 9 hours (OR = 1.19, P < .0005), and ≥ 10 hours (OR = 1.41, P < .0005). When stratified by age, sex, and race/ethnicity groups, short sleep was associated with increased risk for all age groups < 70 years, and long sleep (≥ 10 hours only) was associated with risk for all except < 24 years and > 74 years. Findings for short sleep were relatively consistent across all race/ethnicities, although findings for long sleep were less pronounced among Black/African-American and Other/Multiracial groups. A significant sleep by 3-way sleep × age × sex interaction (P < .0005) suggests that the relationship depends on both age and sex. For both men and women, the OR of having hypertension associated with short sleep decreases with increasing age, but there is a higher association between short sleep and hypertension for women, throughout the adult lifespan.

CONCLUSIONS

Both short and long sleep duration are associated with increased hypertension risk across most age groups. The influence of covariates is stronger upon long sleep relationships. Relationships with short sleep were stronger among younger adults and women.

Disparities in Hypertension Among African-Americans: Implications of Insufficient Sleep

PURPOSE OF REVIEW

Sleep deficiency has been proposed as a potential contributor to racial disparities in cardiovascular health. We present contemporary evidence on the unequal burden of insufficient sleep in Blacks/African-Americans and the repercussions for disparate risk of hypertension.

RECENT FINDINGS

The prevalence of insufficient sleep is high and rising and has been recognized as an important cardiovascular risk factor. Presumably due to a constellation of environmental, psychosocial, and individual determinants, these risks appear exacerbated in Blacks/African-Americans, who are more likely to experience short sleep than other ethnic/racial groups. Population-based data suggest that the risk of hypertension associated with sleep deficiency is greater in those of African ancestry. However, there is a paucity of experimental evidence linking short sleep duration to blood pressure levels in African-Americans. Blacks/African-Americans may be more vulnerable to sleep deficiency and to its hypertensive effects. Future research is needed to unequivocally establish causality and determine the mechanism underlying the postulated racial inequalities in sleep adequacy and consequent cardiovascular risk.

Rapid Eye Movement sleep deprivation of rat generates ROS in the hepatocytes and makes them more susceptible to oxidative stress

Background

Rapid Eye Movement sleep deprivation (REMSD) of rats causes inflammation of the liver and apoptotic cell death of neurons and hepatocytes. Studies also suggest that REM sleep deprivation can cause muscle as well as cardiac injury and neurodegenerative diseases.

Objective and methods

The aim of this research was to determine whether REM sleep deprivation of rats would increase the levels of reactive oxygen species (ROS) in the hepatocytes and create oxidative stress in them. We selectively deprived the rats for REM sleep using the standard flower pot method.

Results

We observed that when rats were subjected to REM sleep deprivation, the levels of ROS in their hepatocytes increased ~184.33% compared to large platform control (LPC) group by day 9 of deprivation, but it returned towards normal level (~49.27%) after recovery sleep for 5 days. Nitric oxide synthase (iNOS) gene expression and protein levels as determined by real-time PCR and western blot analysis respectively were found to be elevated in hepatocytes of REM sleep deprived rats as compared to the LPC group. The level of nitric oxide (NO) in the hepatocytes of REMSD rats also increased by ~404.40% as compared to the LPC group but sleep recovery for 5 days normalized the effect (~135.35% compared to LPC group). We used a large platform control group as a reference group to compare with the REM sleep deprived group as the effect on the hepatocytes of both LPC group and cage control groups were not significantly different.

Discussion

We have analyzed the oxidative stress generated in the hepatocytes of rats due to REM sleep deprivation and further consequences of it. REMS deprivation not only increased the levels of ROS in the hepatocytes but also induced iNOS and NO in them. REM sleep deprived hepatocytes became more susceptible to oxidative stresses on further exposures. Furthermore, our study has great pathological and physiological.