Role of sleep-wake cycle on blood pressure circadian rhythms and hypertension

The emotion paradox in the aging body and brain

With age, parasympathetic activity decreases, while sympathetic activity increases. Thus, the typical older adult has low heart rate variability (HRV) and high noradrenaline levels. Younger adults with this physiological profile tend to be unhappy and stressed. Yet, with age, emotional experience tends to improve. Why does older adults' emotional well-being not suffer as their HRV decreases? To address this apparent paradox, I present the autonomic compensation model. In this model, failing organs, the initial phases of Alzheimer's pathology, and other age-related diseases trigger noradrenergic hyperactivity. To compensate, older brains increase autonomic regulatory activity in the pregenual prefrontal cortex (PFC). Age-related declines in nerve conduction reduce the ability of the pregenual PFC to reduce hyperactive noradrenergic activity and increase peripheral HRV. But these pregenual PFC autonomic compensation efforts have a significant impact in the brain, where they bias processing in favor of stimuli that tend to increase parasympathetic activity (e.g., stimuli that increase feelings of safety) and against stimuli that tend to increase sympathetic activity (e.g., threatening stimuli). In summary, the autonomic compensation model posits that age-related chronic sympathetic/noradrenergic hyperactivity stimulates regulatory attempts that have the side effect of enhancing emotional well-being.

The association between circadian syndrome and chronic kidney disease in an aging population: a 4-year follow-up study

Introduction

Circadian syndrome (CircS) is proposed as a novel risk cluster based on reduced sleep duration, abdominal obesity, depression, hypertension, dyslipidemia and hyperglycemia. However, the association between CircS and chronic kidney disease (CKD) remains unclear. To investigate the cross-sectional and longitudinal association between CircS and CKD, this study was performed.

Methods

A national prospective cohort (China Health and Retirement Longitudinal Study, CHARLS) was used in this study. To define CKD, the estimated glomerular filtration rate (eGFR) was calculated based on the 2012 CKD-EPI creatinine-cystatin C equation. Participants with eGFR <60 mL.min-1/1.73/m2 were diagnosed with CKD. Multivariate binary logistic regression was used to assess the cross-sectional association between CircS and CKD. Subgroup and interactive analyses were performed to determine the interactive effects of covariates. In the sensitivity analysis, the obese population was excluded and another method for calculating the eGFR was used to verify the robustness of previous findings. In addition, participants without CKD at baseline were followed up for four years to investigate the longitudinal relationship between CircS and CKD.

Results

A total of 6355 participants were included in this study. In the full model, CircS was positively associated with CKD (OR = 1.28, 95% CI = 1.04-1.59, P < 0.05). As per one increase of CircS components, there was a 1.11-fold (95% CI = 1.04-1.18, P < 0.05) risk of prevalent CKD in the full model. A significant interactive effect of hyperuricemia in the CircS-CKD association (P for interaction < 0.01) was observed. Sensitivity analyses excluding the obese population and using the 2009 CKD-EPI creatinine equation to diagnose CKD supported the positive correlation between CircS and CKD. In the 2011-2015 follow-up cohort, the CircS group had a 2.18-fold risk of incident CKD (95% CI = 1.33-3.58, P < 0.01) in the full model. The OR was 1.29 (95% CI = 1.10-1.51, P < 0.001) with per one increase of CircS components.

Conclusion

CircS is a risk factor for CKD and may serve as a predictor of CKD for early identification and intervention.

Circadian Syndrome Is Associated with Dietary Patterns among Middle-Older Americans: The Health and Retirement Study

Population aging is a global demographic characteristic of the 21st century, and healthy eating is a core component of healthy aging. However, limited evidence is available among older adults for associations between diet quality and circadian syndrome (CircS). Thus, this study examined associations between dietary patterns and CircS among a representative sample of middle-older adults in the US. The sample comprised middle-older adults enrolled in the 2016 core wave of the Health and Retirement Study (HRS) and one of its sub-studies, the 2013 Health Care and Nutrition Study (HCNS). A food frequency questionnaire was used to quantify habitual food intake and identify dietary patterns using a factor analysis. CircS was defined based on the existence of ≥4 components of metabolic syndrome and indicators of sleep disorders and depression. A total of 4253 middle-older adults with a mean age (SD) of 65.4 (10.0) years were included in the study. The prevalence of CircS was 35.9%. Comparing extreme quartiles of the "Prudent Pattern", the odds ratio (95% CI) for CircS was 0.72 (0.55-0.94), and it was 1.47 (1.10-1.95) for the "Western Pattern". The "Western Pattern" was positively associated while the "Prudent Pattern" was inversely associated with the odds of CircS among middle-older adults.

Narcolepsy and cardiovascular disease: A two-sample Mendelian randomization study

BACKGROUND

Observational findings suggest that patients with narcolepsy are at higher risk for cardiovascular diseases (CVDs), but the potential causal relationship between narcolepsy and CVDs is unclear. Therefore, Mendelian randomization (MR) was used to explore the association between narcolepsy and CVDs.

METHODS

Summary statistics related to narcolepsy, coronary artery disease (CAD), myocardial infarction (MI), heart failure (HF), any stroke (AS), and any ischemic stroke (AIS) were extracted from the public database of relevant published genome-wide association studies (GWAS). Independent single nucleotide polymorphisms were selected as instrumental variables under strict quality control criteria. Inverse variance-weighted (IVW) was the main analytical method to assess causal effects. In addition, we conducted MR pleiotropy residual sum and outlier (MR-PRESSO), weighted median, MR-Egger, and leave-one-out sensitivity analysis to verify the robustness and reliability of the results.

RESULTS

The results of the MR study revealed that narcolepsy was significantly associated with an increased risk of HF (OR = 1.714; 95%CI [1.031-2.849]; P = 0.037), CAD (OR = 1.702; 95%CI [1.011-2.864]; P = 0.045). There was no statistically significant causal association between narcolepsy and MI, AS, and AIS. In addition, further sensitivity analysis showed robust results.

CONCLUSIONS

The results of the two-sample MR study reveal a potential causal relationship between the increased risk of HF and CAD in narcolepsy. These findings emphasize the importance of early monitoring and assessment of cardiovascular risk in patients with narcolepsy.

Familiarization with ambulatory sleep and blood pressure monitoring is necessary for representative data collection

Ambulatory sleep and blood pressure monitoring are gaining popularity as these can be completed in an individual's home. Little is known regarding the reliability of data and the time it takes to acclimate to the equipment. This study aimed to determine how many nights of wearing the monitoring equipment were required to restore sleep architecture and blood pressure data to baseline. It was hypothesized familiarization would be demonstrated by night 3. Ten male and 10 female subjects completed three nights of sleep and blood pressure recordings. At visit 1, the subjects were familiarized with the equipment and instructed to wear the Sleep Profiler{trade mark, serif} and SunTech Medical Oscar2 ambulatory blood pressure cuff simultaneously for three consecutive nights, then subjects returned the equipment. The percent of time spent in rapid eye-movement (REM) sleep was statistically different on night 3 when compared to night 1. Wake-after-sleep onset and sleep latency were not statistically different between nights 1, 2, and 3. Systolic, diastolic, and pulse pressure were all significantly lower on night 3 compared to night 1. Cortical and autonomic arousals were statistically different on night 3. Ambulatory sleep and blood pressure monitoring need at least 3 nights for familiarization. The percent of time spent in REM sleep was statistically different on night 3 when compared to night 1. Systolic blood pressure, diastolic blood pressure, and pulse pressure were all significantly lower on night 3 compared to night 1. Cortical and autonomic arousals were statistically different on nights 3 and 2, respectively compared to night 1. Based on these findings, ambulatory sleep and blood pressure monitoring takes three nights before the data are reliable and the person is familiarized with the mode of measurement. Therefore, it is recommended to use at least three nights of data collection when using the Sleep Profiler and Oscar2 ambulatory blood pressure cuff in order for results to be valid and reliable.

Relationship between daytime napping with the occurrence and development of diabetes: a systematic review and meta-analysis

OBJECTIVE

To determine the relationship of napping with incident diabetes risk and glycaemic control in people with diabetes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE (PubMed), EMBASE, Web of Science and the Cochrane Library were searched for studies published from database inception to 9 May 2023.

ELIGIBILITY CRITERIA

Observational studies reporting the relationship of napping with diabetes or glycaemic control in patients with diabetes in adult populations were included.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently screened the literature, extracted data and assessed the quality of the included studies. The results were reported as ORs and 95% CIs, which were pooled by using fixed and random effects models, and subgroup analyses were performed. The Grading of Recommendations Assessment, Development and Evaluation method was used to assess the quality of the evidence.

RESULTS

Forty studies were included in our review. Habitual napping was associated with an increased diabetes risk (OR 1.20, 95% CI 1.14 to 1.27) and poor glycaemic control in patients with diabetes (OR 2.05, 95% CI 1.55 to 2.73). Nap durations less than 30 min were unrelated to diabetes (OR 1.05, 95% CI 0.97 to 1.14). Nap durations of 30-60 min were associated with diabetes risk (OR 1.09, 95% CI 1.02 to 1.17), but there were differences in the subgroup analysis results. Nap durations of more than 60 min significantly increased the risk of diabetes (OR 1.31, 95% CI 1.20 to 1.44).

CONCLUSIONS

Napping is associated with increased diabetes risk and poor glycaemic control, and future research will need to confirm whether there are sex and regional differences. Nap durations of more than 60 min significantly increases the risk of diabetes, and the relationship between nap duration and glycaemic control in patients with diabetes needs to be further explored in the future.

PROSPERO REGISTRATION NUMBER

CRD42021292103.

Dietary Patterns and Circadian Syndrome among Adults Attending NHANES 2005-2016

The study aimed to assess the associations of dietary patterns and circadian syndrome (CircS). Data from National Health and Nutrition Examination Survey (NHANES) 2005-2016 were analyzed (n = 10,486). Factor analysis was used to construct dietary patterns based on two 24 h food recalls. CircS was defined based on components of the metabolic syndrome, with the addition of short sleep and depression symptoms. Multivariable logistic regression was used to analyze the associations. Two major dietary patterns were identified. The Western dietary pattern had high loadings of refined grains, solid fats, added sugars, and red and cured meats, while the prudent pattern was characterized by a high intake of vegetables, whole grains, oils, nuts, and seeds. The prevalence of CircS was 41.3%. Comparing extreme quartiles of intake, the odds ratios (OR) for having CircS were 1.96 (95%CI 1.53-2.53) and 0.71 (95%CI 0.58-0.86) for the Western pattern and prudent pattern, respectively. The association between the Western dietary pattern and CircS was stronger among men (OR = 2.05; 95%CI 1.48-2.85) and those with low income (OR = 1.94; 95%CI 1.27-2.96) and high education (OR = 3.38; 95%CI 1.90-6.04). The Western dietary pattern was associated with a higher likelihood of having CircS, while the prudent pattern was inversely associated with CircS.

Association of sleep behaviors, insulin resistance surrogates, and the risk of hypertension in Chinese adults with type 2 diabetes mellitus

Objective

Our aim was to evaluate the association between midday napping, combined sleep quality, and insulin resistance surrogates and the risk of hypertension in patients with type 2 diabetes mellitus (T2DM).

Methods

Data were collected using a standardized questionnaire. Binary logistic regression was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) for the risk of hypertension. Systolic and diastolic blood pressure were grouped as categorical variables and unpaired two-sided Student's t-test and Spearman correlation analysis were performed to estimate the association between different blood pressure levels and insulin resistance surrogates.

Results

The overall prevalence rate of hypertension was 50%. Age (OR = 1.056, 95% CI:1.044-1.068), poor sleep quality (OR = 1.959, 95% CI:1.393-2.755), hyperlipidemia (OR = 1.821, 95% CI:1.462-2.369), family history of hypertension (OR = 2.811, 95% CI:2.261-3.495), and obesity (OR = 5.515, 95% CI:1.384-21.971) were significantly associated with an increased risk of hypertension. Midday napping for 1-30 min was negatively correlated with the risk of hypertension (OR = 0.534, 95% CI:0.305-0.936, P <0.05).

Conclusion

Poor sleep quality and obesity are independent risk factors for hypertension. Midday napping (1-30 min) is associated with a decreased risk of hypertension in patients with T2DM.

The association between daytime napping and risk of type 2 diabetes is modulated by inflammation and adiposity: Evidence from 435 342 UK-Biobank participants

BACKGROUND

Existing evidence concerning the relationship between daytime napping and type 2 diabetes (T2D) is inconsistent, and whether the effects of napping differ by body fat percentage (BFP) and C-reactive protein (CRP) is unclear. We aimed to investigate the association between daytime napping frequency and T2D risk and whether such an association was modified by BFP and CRP.

METHODS

We included 435 342 participants free of diabetes from the UK Biobank. Participants were categorized as nonnappers, occasional nappers, and frequent nappers based on napping frequency, and BFP/CRP was divided into quartiles. Cox proportional hazards models were used.

RESULTS

During a median follow-up of 9.2 years, 17 592 T2D cases occurred. Higher frequency of daytime napping was significantly associated with an increased risk of T2D. Compared with nonnappers, the adjusted hazard ratios (HRs) for occasional nappers and habitual nappers were 1.28 (95% confidence interval [CI]: 1.24-1.32) and 1.49 (95% CI: 1.41-1.57), respectively. There was a significant additive and multiplicative interaction (relative excess risk due to interaction [RERI] = 0.490, 95% CI 0.307-0.673; p for multiplicative interaction <.001) between napping and BFP, whereby a higher hazard of T2D associated with more frequent napping was greatest among participants in the highest BFP quartile (HR = 4.45, 95% CI: 3.92-5.06). The results for CRP were similar (RERI = 0.266, 95% CI: 0.094-0.439; p for multiplicative interaction <.001).

CONCLUSIONS

Higher daytime napping frequency is associated with an increased T2D risk, and such relationships are modified by BFP and CRP. These findings underscore the importance of adiposity and inflammation control to mitigate diabetes risk.

Gestational exposure to unmethylated CpG oligonucleotides dysregulates placental molecular clock network and fetoplacental growth dynamics, and disrupts maternal blood pressure circadian rhythms in rats

Bacterial infections and impaired mitochondrial DNA dynamics are associated with adverse pregnancy outcomes. Unmethylated cytosine-guanine dinucleotide (CpG) motifs are common in bacterial and mitochondrial DNA and act as potent immunostimulators. Here, we tested the hypothesis that exposure to CpG oligonucleotides (ODN) during pregnancy would disrupt blood pressure circadian rhythms and the placental molecular clock machinery, mediating aberrant fetoplacental growth dynamics. Rats were repeatedly treated with CpG ODN in the 3 ^rd trimester (gestational day, GD, 14, 16, 18) and euthanized on GD20 (near term) or with a single dose of CpG ODN and euthanized 4 hours after treatment on GD14. Hemodynamic circadian rhythms were analyzed via Lomb-Scargle periodogram analysis on 24-h raw data collected continuously via radiotelemetry. A p -value ≥ 0.05 indicates the absence of a circadian rhythm. Following the first treatment with CpG ODN, maternal systolic and diastolic blood pressure circadian rhythms were lost ( p ≥ 0.05). Blood pressure circadian rhythm was restored by GD16 and remained unaffected after the second treatment with CpG ODN ( p < 0.0001). Diastolic blood pressure circadian rhythm was again lost after the last treatment on GD18 ( p ≥ 0.05). CpG ODN increased placental expression of Per2 and Per3 and Tnfα ( p ≤ 0.05) and affected fetoplacental growth dynamics, such as reduced fetal and placental weights were disproportionately associated with increases in the number of resorptions in ODN-treated dams compared to controls. In conclusion, gestational exposure to unmethylated CpG DNA dysregulates placental molecular clock network and fetoplacental growth dynamics and disrupts blood pressure circadian rhythms.

Association between napping and 24-hour blood pressure variability among university students: A pilot study

Background

Blood pressure variability (BPV) has been reported to be a predictor of cardiovascular and some cognitive diseases. However, the association between napping and BPV remains unknown. This study aimed to explore the association between napping and BPV.

Materials and methods

A cross-sectional study including 105 university students was conducted. Participants' 24 h ambulatory blood pressure monitoring (24 h ABPM) were measured, and napping behaviors were investigated. BPV were measured by the 24 h ABPM, included standard deviation (SD), coefficient of variation (CV), and average real variability (ARV).

Results

Among the participants, 61.9% reported daytime napping. We found that nap duration was significantly associated with daytime CV of diastolic blood pressure (DBP) (r = 0.250, P = 0.010), nighttime CV of systolic blood pressure (SBP) (r = 0.217, P = 0.026), 24 h WCV of DBP (r = 0.238, P = 0.014), 24 h ARV of SBP (r = 0.246, P = 0.011) and 24 h ARV of DBP (r = 0.291, P = 0.003). Compared with the no napping group, 24 h WCV of DBP, daytime CV of DBP, and daytime SD of DBP were significantly higher in participants with napping duration >60 min. With multiple regression analysis we found that nap duration was an independent predictor for 24 h ARV of SBP (β = 0.859, 95% CI, 0.101-1.616, P = 0.027) and 24 h ARV of DBP (β = 0.674, 95% CI, 0.173-1.175, P = 0.009).

Conclusions

Napping durations are associated with BPV among university students. Especially those with napping durations >60 min had a significantly higher BPV than those non-nappers.

Concurrent Aerobic Plus Resistance Training Elicits Different Effects on Short-Term Blood Pressure Variability of Hypertensive Patients in Relation to Their Nocturnal Blood Pressure Pattern

Background and Objectives: The purpose of this study was to investigate the effects of a 12-week concurrent training (CT) (i.e., aerobic plus resistance exercise) on short–term blood pressure variability (BPV) and BP values in hypertensive patients with non-dippper BP nocturnal pattern and underlying coronary artery disease. Material and Methods: The study included 72 consecutive patients who were divided into two groups according to the nocturnal BP pattern: dipping pattern (33 pts) and non-dipping (39 pts). Before starting CT and at 12 weeks, patients underwent the six minute walk test, ergometric test, assessment of 1-repetiton maximum (1 RM), and 24/h BP monitoring (24-h ABPM). Results: After CT, exercise capacity increased in both groups in a similar fashion. Twenty-four/h systolic BPV and daytime systolic BPV decreased significantly in the dipping group while they were unchanged in the non-dipping group (between groups changes: −1.0 ± 0.4 mmHg and −1.3 ± 0.9 mmHg; p = 0.02 and p = 0.006, respectively). Twenty-four/h systolic BP and daytime systolic BP decreased significantly in the dipping group while they were unchanged in the non-dipping group (between groups changes: −7.1 ± 2.6 mmHg and −7.8 ± 2.4 mmHg; p = 0.004 and p = 0.002, respectively). Nighttime systolic BP and BPV was unchanged in both groups. Twenty-four/h diastolic BP presented small but not significant changes in both groups. Conclusions: The effects of CT on BPV and BP were blunted in hypertensive subjects with a non-dipping BP pattern.

The association between bedtime at night and hypertension in adults

OBJECTIVE

This research was conducted to explore the association between bedtime at night and the prevalence of hypertension in adults.

METHODS

We conducted a cross-sectional study of 14,536 participants with data from the NHANES database. Bedtime was determined from the question in the sleep questionnaire: 'What time do you usually fall asleep on weekdays or workdays?.' Hypertension was defined as systolic blood pressure (SBP) ≥ 140 mmHg, or diastolic blood pressure (DBP) ≥ 90 mmHg, or having been told by a doctor to have high blood pressure, or taking antihypertensive medication. We conducted a weighted multiple logistic regression analysis to explore the relationship between bedtime at night and the prevalence of hypertension in adults.

RESULTS

The association between bedtime and hypertension showed a significantly U-shaped relationship. People who went to bed at 23:00 had the lowest risk of developing hypertension (OR, 0.68 [95%CI, 0.58, 0.81]). This U-shaped association still existed in different genders. In males (n = 7159), the adjusted OR was still lowest at 23:00. However, the adjusted OR was lowest at 0:00 in females(n = 7377). The interaction effect between bedtime and gender was significant (P = 0.0187).

CONCLUSION

With the delay in bedtime, the association between bedtime and hypertension showed a significantly U-shaped relationship. Falling asleep at 23:00 has the lowest risk of developing hypertension.

The Circadian Axis and Cardiometabolic Syndrome

Circadian rhythm refers to the daily physiologically fluctuating patterns of systemic processes that occur within a circa 24-hour timeframe, independently of external factors. There is evidence that in time, external and internal cycle misalignment leads to severe health consequences, resulting in the development of cardiometabolic disturbances. Desynchronized hormonal fluctuations along with daily specific macronutrient utilization patterns are also discussed, which by consequence, are all predictors of metabolic syndrome. The aim of this paper is to provide insight on the circadian clock’s organization throughout the human body and to explain the underlying genetic background. By understanding these well-established molecular mechanisms and processes, we believe this paper will provide accuracy regarding the importance of the circadian clock’s integrity and will highlight its role in the etiopathology of cardiometabolic syndrome.

Daytime napping and cardiovascular risk factors, cardiovascular disease, and mortality: A systematic review

Associations between night sleep duration and cardiovascular risk factors in adults have been well documented. However, the associations for daytime napping remain unclear. In this review, six databases were searched for eligible publications to April 8, 2022. A total of 11 articles were identified for umbrella review on the association of daytime napping with diabetes, metabolic syndrome (MetS), cardiovascular disease (CVD), and mortality in adults, 97 for systematic review on the association with CVD and several CVD risk factors. Our umbrella review showed that the associations of daytime napping with diabetes, MetS, CVD, and mortality in most meta-analyses were mainly supported by weak or suggestive evidence. Our systematic review showed that long daytime napping (≥1 h/d) was associated with higher odds of several CVD risk factors, CVD, and mortality, but no significant association was found between short daytime napping and most of the abovementioned outcomes. Our dose-response meta-analyses showed that daytime napping <30 min/d was not significantly associated with higher odds of most CVD risk factors and CVD among young and middle-aged adults. However, among older adults aged >60 years, we observed significant dose-response associations of daytime napping with higher odds of diabetes, dyslipidemia, MetS, and mortality starting from 0 min/d.

New insight into ischemic stroke: Circadian rhythm in post-stroke angiogenesis

The circadian rhythm is an endogenous clock system that coordinates and optimizes various physiological and pathophysiological processes, which accord with the master and the peripheral clock. Increasing evidence indicates that endogenous circadian rhythm disruption is involved in the lesion volume and recovery of ischemic stroke. As a critical recovery mechanism in post-stroke, angiogenesis reestablishes the regional blood supply and enhances cognitive and behavioral abilities, which is mainly composed of the following processes: endothelial cell proliferation, migration, and pericyte recruitment. The available evidence revealed that the circadian governs many aspects of angiogenesis. This study reviews the mechanism by which circadian rhythms regulate the process of angiogenesis and its contribution to functional recovery in post-stroke at the aspects of the molecular level. A comprehensive understanding of the circadian clock regulating angiogenesis in post-stroke is expected to develop new strategies for the treatment of cerebral infarction.

Time of day as a critical variable in biology

BACKGROUND

Circadian rhythms are important for all aspects of biology; virtually every aspect of biological function varies according to time of day. Although this is well known, variation across the day is also often ignored in the design and reporting of research. For this review, we analyzed the top 50 cited papers across 10 major domains of the biological sciences in the calendar year 2015. We repeated this analysis for the year 2019, hypothesizing that the awarding of a Nobel Prize in 2017 for achievements in the field of circadian biology would highlight the importance of circadian rhythms for scientists across many disciplines, and improve time-of-day reporting.

RESULTS

Our analyses of these 1000 empirical papers, however, revealed that most failed to include sufficient temporal details when describing experimental methods and that few systematic differences in time-of-day reporting existed between 2015 and 2019. Overall, only 6.1% of reports included time-of-day information about experimental measures and manipulations sufficient to permit replication.

CONCLUSIONS

Circadian rhythms are a defining feature of biological systems, and knowing when in the circadian day these systems are evaluated is fundamentally important information. Failing to account for time of day hampers reproducibility across laboratories, complicates interpretation of results, and reduces the value of data based predominantly on nocturnal animals when extrapolating to diurnal humans.

Positive association of nap duration with risk of non-alcoholic fatty liver disease in an occupational population in Guangdong Province, China: a cross-sectional study

BACKGROUND

A lack of sleep or disorder in sleep-wake cycles has been associated with metabolic impairments. However, few studies have investigated the association between daytime napping duration and the risk of non-alcoholic fatty liver disease. This study aimed to investigate the association of daytime napping duration with the risk of non-alcoholic fatty liver disease in a Chinese population.

METHODS

This cross-sectional study analyzed data from the Health Management Center of Nanfang Hospital, Guangdong Province. A total of 3363 participants aged 20-79 years were recruited and admitted from January 20, 2018, to October 16, 2020. Non-alcoholic fatty liver disease was diagnosed using abdominal ultrasonography. The outcome was the association between daytime sleep duration and the risk of non-alcoholic fatty liver disease.

RESULTS

Compared with non-nappers, long daytime nappers (≥ 60 min) were associated with a higher risk of non-alcoholic fatty liver disease in the crude model (odds ratio 2.138; 95% confidence interval 1.88-2.61, P < 0.05) and in the multivariable adjustment model (odds ratio 2.211; 95% confidence interval 1.042-4.690, P < 0.05) after adjusting for demographic, educational, and metabolic risk factors. The association was moderately enhanced with additional adjustments for night sleep duration and socioeconomic or other factors (odds ratio 2.253; 95% confidence interval 1.061-4.786, P = 0.035).

CONCLUSION

In this cross-sectional study, daytime napping duration of ≥ 60 min was positively associated with the risk of non-alcoholic fatty liver disease in an occupational population of Guangdong Province after multivariable adjustment.

Bioheat Transfer Basis of Human Thermoregulation: Principles and Applications

Thermoregulation is a process that is essential to the maintenance of life for all warm-blooded mammalian and avian species. It sustains a constant core body temperature in the face of a wide array of environmental thermal conditions and intensity of physical activities that generate internal heat. A primary component of thermoregulatory function is the movement of heat between the body core and the surface via the circulation of blood. The peripheral vasculature acts as a forced convection heat exchanger between blood and local peripheral tissues throughout the body enabling heat to be convected to the skin surface where is may be transferred to and from the environment via conduction, convection, radiation, and/or evaporation of water as local conditions dictate. Humans have evolved a particular vascular structure in glabrous (hairless) skin that is especially well suited for heat exchange. These vessels are called arteriovenous anastomoses (AVAs) and can vasodilate to large diameters and accommodate high flow rates. We report herein a new technology based on a physiological principle that enables simple and safe access to the thermoregulatory control system to allow manipulation of thermoregulatory function. The technology operates by applying a small amount of heating local to control tissue on the body surface overlying the cerebral spine that upregulates AVA perfusion. Under this action, heat exchangers can be applied to glabrous skin, preferably on the palms and soles, to alter the temperature of elevated blood flow prior to its return to the core. Therapeutic and prophylactic applications are discussed.

Association between sleep duration on workdays and blood pressure in non-overweight/obese population in NHANES: a public database research

This study aimed to explore the association between sleep duration on workdays and blood pressure (BP) including systolic blood pressure (SBP) and diastolic blood pressure (DBP) in non-overweight/obese population. A cross-sectional study composed of 2887 individuals from NHANES was conducted. Subjective sleep duration on workdays were evaluated by the questionnaire. Multiple linear regression analyses were done to explore the relationship between sleep duration and BP. Compared with sleep duration of 6-8 h, both sleep duration < 6 h and ≥ 8 h on workdays were significantly associated with increased SBP (β, 3.58 [95% CI 1.60, 5.56] and 1.70 [95% CI 0.76, 2.64], respectively). However, the significant association was not founded in DBP. The stratified analyses showed that in females, sleep duration (< 6 h or ≥ 8 h) on workdays were associated with SBP (β = 5.99 and 2.41, respectively, both P < 0.0005). In addition, the SBP levels were much higher among participants aged (≥ 60) with sleep duration < 6 h. The effect size was 7.23 (P = 0.0217). In the subgroup classified by race, a significantly positive association between sleep duration (< 6 h, ≥ 8 h) and SBP can be seen in the White population (β = 6.64 (P = 0.0007) and 1.91 (P = 0.0215), respectively). In non-overweight/obese population, both short sleep duration (< 6 h) and long sleep duration (≥ 8 h) on workdays were correlated with higher level of SBP.

Association Between Bedtime at Night and Systolic Blood Pressure in Adults in NHANES

Objectives: This study aimed to explore the association between bedtime at night and systolic blood pressure (SBP) in adults.

Methods: We conducted a cross-sectional study composed of 7,642 individuals from the National Health and Nutrition Examination Survey (NHANES). Bedtime was defined as the response to the question: “What time do you usually fall asleep on weekdays or workdays?” SBP was taken using the average of all measured values. Multiple linear regression analyses were done to explore the relationship between bedtime and SBP.

Results: The bedtime was changed from categorical variable to continuous variable for data analysis, and a significantly negative association was identified between bedtime and SBP (β, −0.23 [95% CI, −0.43, −0.02]). With the delay of bedtime, the SBP showed a gradual decrease trend, and it was dropped to the lowest at 0:00. After 0:00, the SBP was gradually increased with the delay of sleep time. The stratified analyses showed that in the female group, with the delay of bedtime, the range of SBP was decreased more obviously at 0:00. In the 18–45 year group, bedtime had little effect on SBP. Among ≥45 years old group, this trend was still the same. In the black group, an obvious downward trend was found at 22:00.

Conclusion: With the delay of bedtime, the SBP had shown a gradual decrease trend, and it was dropped to the lowest at 0:00. After 0:00, the SBP was gradually increased with the delay of sleep time. Bedtime and SBP showed a U-shaped relationship.

Association Between Sleep Quality and Hypertension in Chinese Adults: A Cross-Sectional Analysis in the Tianning Cohort

BACKGROUND

Poor sleep quality is becoming very common in a developed society and relates to many health disorders. However, the association between sleep quality and hypertension has not been well studied in Chinese adults.

METHODS

Blood pressure was measured and sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI) for 5167 participants (mean aged 51±15 years, 41.5% males) in the Tianning Cohort. A logistic regression model was constructed to examine the association between sleep quality, as well as its components, and hypertension, adjusting for age, sex, education level, current smoking, current drinking, physical activity, obesity, glucose, and blood lipids.

RESULTS

After multivariate adjustment, a higher score Of the PSQI was significantly associated with an increased risk of prevalent hypertension (OR=1.03, P=0.018). Compared to participants with normal sleep (the PSQI score <5), those with a poor sleep quality (the PSQI score ≥5) had a 17% increased risk of prevalent hypertension (OR=1.17, P=0.042). Three of the seven components of sleep quality, such as subjective sleep quality (OR=1.17, P=0.001), sleep latency (OR=1.11, P=0.010), and sleep disturbances (OR=1.19, P=0.004), were also significantly associated with prevalent hypertension.

CONCLUSION

Poor sleep quality is increasingly prevalent in developed societies and may be related to an increased risk of hypertension in Chinese adults. The underlying causality is waiting to be studied.

Ingestion-time differences in the pharmacodynamics of dual-combination hypertension therapies: Systematic review and meta-analysis of published human trials

The pharmacodynamics of hypertension medications can be significantly affected by circadian rhythms in the biological mechanisms of the 24 h blood pressure (BP) pattern. Hypertension guidelines fail to recommend the time of day when patients, including those who require treatment with multiple medications, are to ingest BP-lowering therapy. We conducted a systematic review of published prospective trials that investigated hypertension medications for ingestion-time differences in BP-lowering, safety, patient adherence, and markers of target organ pathology. Among the search-retried 155 trials, 17 published between 1991 and 2020 totaling 1,508 hypertensive participants concerned the differential ingestion-time dependent effects of 14 unique dual-combination therapies. All but one (94.1%) of the trials, involving 98.5% of the total number of investigated individuals, reported clinically and statistically significant benefits - including enhanced reduction of asleep BP without induction of sleep-time hypotension, reduced prevalence of BP non-dipping, decreased adverse effects, improved kidney function, and reduced cardiac pathology - when dual-combination hypertension medications were ingested at-bedtime/evening rather than upon-waking/morning. A systematic and comprehensive review of the literature published in the past three decades reveals no single dual-combination hypertension trial reported significantly better benefit of the still conventional, yet unjustified by medical evidence, upon-waking/morning hypertension treatment scheme.

The Circadian Rhythm of Thermoregulation Modulates both the Sleep/Wake Cycle and 24 h Pattern of Arterial Blood Pressure

Borbély proposed an interacting two-component model of sleep regulation comprising a homeostatic Process S and a circadian Process C. The model has provided understanding of the association between core body temperature (CBT) as a key element of Process C that is deterministic of sleep onset and offset. However, it additionally provides a new perspective of the importance of the thermoregulatory mechanisms of Process C in modulating the circadian rhythm of arterial blood pressure (ABP). Herein, we examine the circadian physiology of thermoregulation, including at the end of the activity span the profound redistribution of cardiac output from the systemic circulation to the arteriovenous anastomoses of the glabrous skin that markedly enhances convective transfer of heat from the body to the environment to cause (i) decrease of the CBT as a pathway to sleep onset and (ii) attenuation of the asleep ABP mean and augmentation of the ABP decline (dipping) from the wake-time mean, in combination the strongest predictors of the risk for blood vessel and organ pathology and morbid and mortal cardiovascular disease events. We additionally review the means by which blood perfusion to the glabrous skin can be manipulated on demand by selective thermal stimulation, that is, mild warming, on the skin of the cervical spinal cord to intensify Process C as a way to facilitate sleep induction and promote healthy asleep ABP. © 2021 American Physiological Society. Compr Physiol 11:1-14, 2021.

Elevated asleep blood pressure and non-dipper 24h patterning best predict risk for heart failure that can be averted by bedtime hypertension chronotherapy: A review of the published literature

Several prospective studies consistently report elevated asleep blood pressure (BP) and blunted sleep-time relative systolic BP (SBP) decline (non-dipping) are jointly the most significant prognostic markers of cardiovascular disease (CVD) risk, including heart failure (HF); therefore, they, rather than office BP measurements (OBPM) and ambulatory awake and 24 h BP means, seemingly are the most worthy therapeutic targets for prevention. Published studies of the 24 h BP pattern in HF are sparse in number and of limited sample size. They report high prevalence of the abnormal non-dipper/riser 24 h SBP patterning. Despite the established clinical relevance of the asleep BP, past as do present hypertension guidelines recommend the diagnosis of hypertension rely on OBPM and, when around-the-clock ambulatory BP monitoring (ABPM) is conducted to confirm the elevated OBPM, either on the derived 24 h or "daytime" BP means. Additionally, hypertension guidelines do not advise the time-of-day when BP-lowering medications should be ingested, in spite of known ingestion-time differences in their pharmacokinetics and pharmacodynamics. Between 1976 and 2020, 155 unique trials of ingestion-time differences in the effects of 37 different single and 14 dual-combination hypertension medications, collectively involving 23,972 patients, were published. The vast majority (83.9%) of them found the at-bedtime/evening in comparison to upon-waking/morning treatment schedule resulted in more greatly enhanced: (i) reduction of asleep BP mean without induced sleep-time hypotension; (ii) reduction of the prevalence of the higher CVD risk non-dipper/riser 24 h BP phenotypes; (iii) improvement of kidney function, reduction of cardiac pathology, and with lower incidence of adverse effects. Most notably, no single published randomized trial found significantly better BP-lowering, particularly during sleep, or medical benefits of the most popular upon-waking/morning hypertension treatment-time scheme. Additionally, prospective outcome trials have substantiated that the bedtime relative to the upon-waking, ingestion of BP-lowering medications not only significantly reduces risk of HF but also improves overall CVD event-free survival time.

Melatonin in Early Nutrition: Long-Term Effects on Cardiovascular System

Breastfeeding protects against adverse cardiovascular outcomes in the long term. Melatonin is an active molecule that is present in the breast milk produced at night beginning in the first stages of lactation. This indoleamine appears to be a relevant contributor to the benefits of breast milk because it can affect infant health in several ways. The melatonin concentration in breast milk varies in a circadian pattern, making breast milk a chrononutrient. The consumption of melatonin can induce the first circadian stimulation in the infant's body at an age when his/her own circadian machinery is not functioning yet. This molecule is also a powerful antioxidant with the ability to act on infant cells directly as a scavenger and indirectly by lowering oxidant molecule production and enhancing the antioxidant capacity of the body. Melatonin also participates in regulating inflammation. Furthermore, melatonin can participate in shaping the gut microbiota composition, richness, and variation over time, also modulating which molecules are absorbed by the host. In all these ways, melatonin from breast milk influences weight gain in infants, limiting the development of obesity and comorbidities in the long term, and it can help shape the ideal cellular environment for the development of the infant's cardiovascular system.

Time-restricted feeding protects the blood pressure circadian rhythm in diabetic mice

The quantity and quality of food intake have been considered crucial for peoples' wellness. Only recently has it become appreciated that the timing of food intake is also critical. Nondipping blood pressure (BP) is prevalent in diabetic patients and is associated with increased cardiovascular events. However, the causes and mechanisms of nondipping BP in diabetes are not fully understood. Here, we report that food intake and BP were arrhythmic in diabetic db/db mice fed a normal chow diet ad libitum. Imposing a food intake diurnal rhythm by time-restricted feeding (TRF; food was only available for 8 h during the active phase) prevented db/db mice from developing nondipping BP and effectively restored the already disrupted BP circadian rhythm in db/db mice. Interestingly, increasing the time of food availability from 8 h to 12 h during the active dark phase in db/db mice prompted isocaloric feeding and still provided robust protection of the BP circadian rhythm in db/db mice. In contrast, neither 8-h nor 12-h TRF affected BP dipping in wild-type mice. Mechanistically, we demonstrate that TRF protects the BP circadian rhythm in db/db mice via suppressing the sympathetic activity during the light phase when they are inactive and fasting. Collectively, these data reveal a potentially pivotal role of the timing of food intake in the prevention and treatment of nondipping BP in diabetes.

Systematic review and quality evaluation of published human ingestion-time trials of blood pressure-lowering medications and their combinations

The pharmacokinetics (PK) - absorption, distribution, metabolism, and elimination - and pharmacodynamics (PD) of hypertension medications can be significantly affected by circadian rhythms. As a consequence, the time when blood pressure (BP) lowering medications are ingested, with reference to the staging of all involved circadian rhythms modulating PK and PD, can affect their duration of action, magnitude of effect on features of the 24 h BP profile, and safety. We conducted a systematic and comprehensive review of published prospective human trials that investigated individual hypertension medications of all classes and their combinations for ingestion-time differences in BP-lowering, safety, patient adherence, and markers of hypertension-associated target organ pathology of the kidney and heart. The systematic review yielded 155 trials published between 1976 and 2020 - totaling 23,972 hypertensive individuals - that evaluated 37 different single and 14 dual-combination therapies. The vast (83.9%) majority of them reported clinically and statistically significant benefits - including enhanced reduction of asleep BP mean without induced sleep-time hypotension, reduced prevalence of the higher cardiovascular risk non-dipper 24 h BP profile, decreased incidence of adverse effects, improved kidney function, and reduced cardiac pathology - when hypertension medications are ingested at-bedtime/evening rather than upon-waking/morning. Nonetheless, the findings and conclusions of some past conducted trials are inconsistent, often due to disparities and deficiencies of the investigative protocols. Accordingly, we developed a quality assessment method based upon the eight items identified as crucial according to the recently published guidelines of the International Society for Chronobiology and the American Association for Medical Chronobiology and Chronotherapeutics for the design and conduct of human clinical trials on ingestion-time differences of hypertension medications. Among the most frequent deficiencies are: absence or miscalculation of minimum required sample size (83.2%), incorrect choice of primary BP endpoint (53.6%), and inappropriate arbitrary and unrepresentative clock hours chosen for tested treatment times (53.6%). The inability of the very small proportion (16.1%) of trials to verify the advantages of the at-bedtime/evening treatment strategy is likely explained by deficiencies of their study design and conduct. Nonetheless, regardless of the quality score of the 155 trials retrieved by our systematic review, it is most noteworthy that no single published prospective randomized trial reported significantly enhanced BP-lowering, safety, compliance, or other benefits of the unjustified by medical evidence, yet still most recommended, upon-waking/morning hypertension treatment-time scheme.

Daytime Napping and Nighttime Sleep Duration with Incident Diabetes Mellitus: A Cohort Study in Chinese Older Adults

Background: We aimed to examine the longitudinal associations between daytime napping and nighttime sleep duration with the risk of diabetes mellitus (DM) among Chinese elderly using data from the China Health and Retirement Longitudinal Study (CHARLS). Methods: A cohort study was conducted among 2620 participants aged 60 years or above. Information on daytime napping and nighttime sleep duration was self-reported during the 2011 baseline survey. DM status during the 2015 follow-up survey was confirmed according to the American Diabetes Association criteria. Results: Individuals with long daytime napping (>1 h/day) had increased risk of developing DM than non-nappers (adjusted RR = 1.52, 95%CI: 1.10, 2.10). In addition, we observed a U-shaped association between nighttime sleep duration and incident DM risk. We further found that nappers with <4 h of nighttime sleep, and those with >1 h of daytime napping and >6 h nighttime sleep had approximately two-fold elevated risk of DM, compared to non-nappers with 6–8 h of nighttime sleep. Conclusion: Long daytime napping and extreme nighttime sleep duration were associated with increased DM risk among Chinese elderly. There was a joint effect of long daytime napping and nighttime sleep duration on the risk of DM.

Sleeping Duration, Napping and Snoring in Association with Diabetes Control among Patients with Diabetes in Qatar

BACKGROUND

Poor glycemic control is associated with chronic life-threatening complications. Several studies have revealed that sleep status is associated with glycemic control.

AIM

to examine the association between sleep duration, quality and glycemic control among adults with diabetes.

METHODS

Data on 2500 participants aged 18-60 years were collected from the Qatar Biobank (QBB). Sleep duration and quality were assessed by a self-completed health and lifestyle questionnaire, and glycemic control was assessed using HbA1c. Logistic regression was used to assess the association between sleep duration, napping, snoring and poor glycemic control.

RESULTS

After adjusting for age and gender, sleep duration was not associated with poor glycemic control. Lack of association persisted after controlling for smoking, physical activity, education, BMI, fruit and vegetable intake, insulin and medication use. However, sleeping for long hours at night (≥8 h) had a trend in increasing the risk of poor glycemic control (OR = 1.28; 95% CI: 0.94-1.74). Napping was positively associated with poor glycemic control. After adjusting for age and gender, patients who reported "sometimes, frequently, or always" napping had more than 30% increased risk of poor control as compared to patients who reported "never/rarely" napping. Snoring was not associated with poor glycemic control among the study sample when adjusted for age and gender (p = 0.61). Other factors were found to be associated with a better glycemic control such as female, high educational and high physical activity level.

CONCLUSIONS

our results suggest that napping may be an independent risk factor for a poor glycemic control in diabetes; further investigations are required.

Long-term continuous positive airway pressure treatment ameliorates biological clock disruptions in obstructive sleep apnea

BACKGROUND

Obstructive Sleep Apnea (OSA) is a highly prevalent and underdiagnosed sleep disorder. Recent studies suggest that OSA might disrupt the biological clock, potentially causing or worsening OSA-associated comorbidities. However, the effect of OSA treatment on clock disruption is not fully understood.

METHODS

The impact of OSA and short- (four months) and long-term (two years) OSA treatment, with Continuous Positive Airway Pressure (CPAP), on the biological clock was investigated at four time points within 24 h, in OSA patients relative to controls subjects (no OSA) of the same sex and age group, in a case-control study. Plasma melatonin and cortisol, body temperature and the expression levels and rhythmicity of eleven clock genes in peripheral blood mononuclear cells (PBMCs) were assessed. Additional computational tools were used for a detailed data analysis.

FINDINGS

OSA impacts on clock outputs and on the expression of several clock genes in PBMCs. Neither short- nor long-term treatment fully reverted OSA-induced alterations in the expression of clock genes. However, long-term treatment was able to re-establish levels of plasma melatonin and cortisol and body temperature. Machine learning methods could discriminate controls from untreated OSA patients. Following long-term treatment, the distinction between controls and patients disappeared, suggesting a closer similarity of the phenotypes.

INTERPRETATION

OSA alters biological clock-related characteristics that differentially respond to short- and long-term CPAP treatment. Long-term CPAP was more efficient in counteracting OSA impact on the clock, but the obtained results suggest that it is not fully effective. A better understanding of the impact of OSA and OSA treatment on the clock may open new avenues to OSA diagnosis, monitoring and treatment.

Extent of asleep blood pressure reduction by hypertension medications is ingestion-time dependent: Systematic review and meta-analysis of published human trials

Combined evidence of published prospective outcome trials and meta-analyses substantiate elevated asleep blood pressure (BP) and blunted sleep-time relative BP decline (non-dipping), regardless of wake-time office BP and awake or 24 h BP means, are jointly the most highly significant independent prognostic markers of cardiovascular disease (CVD) risk and worthy therapeutic targets for prevention. Nonetheless, current guidelines continue to recommend the diagnosis of hypertension, when based on ambulatory BP monitoring (ABPM), rely, solely, on either the 24 h or "daytime" BP means. They also fail to recommend the time to treat patients. We conducted a systematic review of published human trials regarding ingestion-time differences in the effects of hypertension medications on asleep BP and sleep-time relative BP decline. Some 62 such trials published between 1992 and 2020, totaling 6120 hypertensive persons, evaluated 21 different single and 8 dual-fixed combination therapies. The vast (82.3%) majority of the trials substantiate the bedtime/evening vs. upon-waking/morning treatment schedule produces statistically significant better clinical benefits, including enhanced reduction of asleep systolic BP by an average 5.17 mmHg (95%CI [4.04, 6.31], P < 0.001 between treatment-time groups) without inducing sleep-time hypotension, reduced prevalence of the high CVD risk non-dipper 24 h BP pattern, improved kidney function, and reduced cardiac pathology. Furthermore, systematic and comprehensive review of the ABPM-based literature published the past 29 years reveals no single study that reported significantly better benefits of the most recommended, yet unjustified by medical evidence, morning hypertension treatment-time scheme.

Objective short sleep duration and 24-hour blood pressure

Background

Short sleep duration is a contributor to cardiovascular disease (CVD) events and mortality. Short sleep duration is associated with an increased risk of high clinic blood pressure (BP). BP measured outside the clinic using 24-h ambulatory blood pressure monitoring (ABPM) is a better predictor of an individual's CVD risk. We examined the association between objectively-assessed sleep duration and 24-h ambulatory blood pressure (ABP).

Methods

A total of 893 working adults underwent sleep and ABPM. Participants were fitted with an ABPM device, and measures were taken at 28-30 min intervals. Objective sleep duration, and times of wakefulness and sleep during the 24-h ABPM period were derived from wrist-worn actigraphy. Linear regression, adjusted for age, sex, race/ethnicity, body mass index, smoking status, and diabetes were conducted on the relationship between sleep duration and the ABP measures.

Results

Mean age of participants (final n = 729, 59.5% female, 11.9% Hispanic) was 45.2 ± 10.4 y. Mean actigraphy-derived sleep duration was 6.8 ± 1.2 h. Sleep duration <6 h was associated with a 1.73 mmHg higher 24-h systolic BP (p = 0.031) and 2.17 mmHg higher 24-h diastolic BP (p < 0.001). Shorter sleep duration was not associated with mean awake or asleep systolic BP (p = 0.89 and p = 0.92) or mean awake or asleep diastolic BP (p = 0.30 and p = 0.74).

Conclusions

To our knowledge, this is the largest study conducted which assessed sleep duration objectively while measuring 24-h ABP. Shorter sleep duration is associated with higher 24-h BP and potentially cardiovascular risk.

Guidelines for the design and conduct of human clinical trials on ingestion-time differences - chronopharmacology and chronotherapy - of hypertension medications

Current hypertension guidelines fail to provide a recommendation on when-to-treat, thus disregarding relevant circadian rhythms that regulate blood pressure (BP) level and 24 h patterning and medication pharmacokinetics and pharmacodynamics. The ideal purpose of ingestion-time (chronopharmacology, i.e. biological rhythm-dependent effects on the kinetics and dynamics of medications, and chronotherapy, i.e. the timing of pharmaceutical and other treatments to optimize efficacy and safety) trials should be to explore the potential impact of endogenous circadian rhythms on the effects of medications. Such investigations and outcome trials mandate adherence to the basic standards of human chronobiology research. In-depth review of the more than 150 human hypertension pharmacology and therapeutic trials published since 1974 that address the differential impact of upon-waking/morning versus at-bedtime/evening schedule of treatment reveals diverse protocols of sometimes suboptimal or defective design and conduct. Many have been "time-of-day," i.e. morning versus evening, rather than circadian-time-based, and some relied on wake-time office BP rather than around-the-clock ambulatory BP measurements (ABPM). Additionally, most past studies have been of too small sample size and thus statistically underpowered. As of yet, there has been no consensual agreement on the proper design, methods and conduct of such trials. This Position Statement recommends ingestion-time hypertension trials to follow minimum guidelines: (i) Recruitment of participants should be restricted to hypertensive individuals diagnosed according to ABPM diagnostic thresholds and of a comparable activity/sleep routine. (ii) Tested treatment-times should be selected according to internal biological time, expressed by the awakening and bed times of the sleep/wake cycle. (iii) ABPM should be the primary or sole method of BP assessment. (iv) The minimum-required features for analysis of the ABPM-determined 24 h BP pattern ought to be the asleep (not "nighttime") BP mean and sleep-time relative BP decline, calculated in reference to the activity/rest cycle per individual. (v) ABPM-obtained BP means should be derived by the so-called adjusted calculation procedure, not by inaccurate arithmetic averages. (vi) ABPM should be performed with validated and calibrated devices at least hourly throughout two or more consecutive 24 h periods (48 h in total) to achieve the highest reproducibility of mean wake-time, sleep-time and 48 h BP values plus the reliable classification of dipping status. (vii) Calculation of minimum required sample size in adherence with proper statistical methods must be provided. (viii) Hypertension chronopharmacology and chronotherapy trials should preferably be randomized double-blind, randomized open-label with blinded-endpoint, or crossover in design, the latter with sufficient washout period between tested treatment-time regimens.

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.

Acute Spontaneous Cervical Spinal Epidural Haematoma a Very Rare Presentation Mimicking of Carotid Dissection during Sleep

Acute spontaneous spinal epidural hematoma without any identified etiology is a rare phenomenon and an uncommon cause of acute spinal cord compression. We report a case of acute spontaneous cervical spinal epidural hematoma, with sudden onset of acute neck pain and left-side body weakness during sleep which resembling of cervicle carotid dissection. The pain commenced suddenly, early in the morning while the patient was asleep. He had no previous history of any relevant medical disorder. Cervical Spine MRI revealed a cervical epidural haematoma at C3/C4, mainly on the left side, with spinal cord compression. Therefore, an emergent C3/C6 hemilaminectomy and evacuation of hematoma were carried out within 24 h of presentation. The patient's neck pain resolved after surgery and he was able to walk, though he required bladder catheterization on discharge after 1 week. He has nearly intact motor neurological examination in the second month of the operation.

New perspectives on the definition, diagnosis, and treatment of true arterial hypertension

INTRODUCTION

Office blood pressure measurements (OBPM), still used today for diagnosis and management of hypertension, fail to reveal clinically important features of the mostly predictable blood pressure (BP) 24 h pattern, and lead to >45% of individuals being misclassified. Current hypertension guidelines do not provide recommendation on when-to-treat, despite multiple prospective clinical trials documenting improved normalization of 24 h BP pattern and significant reduction in cardiovascular disease (CVD) events when hypertension medications are ingested at bedtime rather than upon waking.

AREAS COVERED

In this review, the authors discuss current evidence on the: (i) most relevant attributes of the 24 h BP pattern deterministic of CVD risk; (ii) asleep systolic BP (SBP) mean as the most significant therapeutic target for CVD risk reduction; (iii) ingestion-time differences in pharmacodynamics of BP-lowering medications as reported with high consistency in multiple clinical trials; and (iv) enhanced prevention of CVD events achieved by bedtime hypertension chronotherapy.

EXPERT OPINION

Several prospective trials consistently document asleep SBP mean and sleep-time relative SBP decline (dipping) constitute highly significant CVD risk factors, independent of OBPM. Bedtime, compared to customary upon-waking, hypertension chronotherapy reduces risk of major CVD events. Collectively, these findings call for new definition of true hypertension and, accordingly, its proper diagnosis and management.

Effects of obstructive sleep apnea on endogenous circadian rhythms assessed during relaxed wakefulness; an exploratory analysis

Obstructive sleep apnea (OSA) is associated with hypertension, cardiovascular disease, and a change in the 24 h pattern of adverse cardiovascular events and mortality. Adverse cardiovascular events occur more frequently in the middle of the night in people with OSA, earlier than the morning prevalence of these events in the general population. It is unknown if these changes are associated with a change in the underlying circadian rhythms, independent of behaviors such as sleep, physical activity, and meal intake. In this exploratory analysis, we studied the endogenous circadian rhythms of blood pressure, heart rate, melatonin and cortisol in 11 participants (48 ± 4 years; seven with OSA) throughout a 5 day study that was originally designed to examine circadian characteristics of obstructive apnea events. After a baseline night, participants completed 10 recurring 5 h 20 min behavioral cycles divided evenly into standardized sleep and wake periods. Blood pressure and heart rate were recorded in a relaxed semirecumbent posture 15 minutes after each scheduled wake time. Salivary melatonin and cortisol concentrations were measured at 1-1.5 h intervals during wakefulness. Mixed-model cosinor analyses were performed to determine the rhythmicity of all variables with respect to external time and separately to circadian phases (aligned to the dim light melatonin onset, DLMO). The circadian rhythm of blood pressure peaked much later in OSA compared to control participants (group × circadian phase, p < .05); there was also a trend toward a slightly delayed cortisol rhythm in the OSA group. Rhythms of heart rate and melatonin did not differ between the groups. In this exploratory analysis, OSA appears to be associated with a phase change (relative to DLMO) in the endogenous circadian rhythm of blood pressure during relaxed wakefulness, independent of common daily behaviors.

Bedtimes and Blood Pressure: A Prospective Cohort Study of Mexican Adolescents

INTRODUCTION

Hypertension affects up to 5% of children worldwide and predicts later cardiovascular morbidity. Associations of short sleep and hypertension have been frequently reported in adults but less consistently in children. This study aims to examine the role of late bedtimes, a marker of short sleep duration, and potentially misaligned circadian rhythms, on incident elevated blood pressure (BP) in a large cohort of Mexican children.

METHODS

Participants included 2,033 adolescents recruited from public schools in Morelos, Mexico, free from elevated BP (<90th sex, age, and height-standardized percentile). Fourteen months later, all adolescents had a second BP assessment. We abstracted baseline habitual bedtimes from questionnaires to evaluate the association between bedtime and elevated BP incidence (≥90th percentile). Risk ratios and 95% confidence intervals were estimated with discrete-time mixed survival models, adjusting for potential confounders and accounting for clustering by school.

RESULTS

Participants were 12.5 (SD = 0.6) years old at baseline. At the follow-up visit 10% of adolescents had developed elevated BP. Compared to participants with a habitual weekday bedtime between 9 and 10 pm, those with a weekday bedtime 11 pm or later had a 1.87 times higher risk of developing elevated BP over the follow-up period (95% CI = 1.09, 2.21), after accounting for confounders. Participants with earlier weekday bedtimes also had a higher risk of elevated BP (RR = 1.96; 95% CI = 1.27, 3.01). The associations persisted after accounting for wake time.

CONCLUSION

These data showed a U-shaped association between weekday bedtime and elevated/high BP risk among Mexican adolescents.

The association of urinary uric acid excretion with ambulatory blood pressure values in patients with chronic kidney disease

BACKGROUND

To analyze the association between hypertension and urinary uric acid excretion in patients with chronic kidney disease (CKD).

METHODS

We screened 87 patients who had been admitted at the Dept of Nephrology, Huadong hospital between April 2017 to April 2019 who had completed 24-h ambulatory blood pressure monitoring and retained 24-h urine biochemical test specimens, thirty adult patients (age ≤ 65 years) with CKD 1-2 stages were recruited in the study. Pearson's correlation analysis and multiple linear regression analysis were used to study the correlation of urinary uric acid excretion with ambulatory blood pressure values and the association of morning mean diastolic pressure (mMDP), night mean diastolic pressure (nMDP) and CV of dMSP (coefficient of variation of day mean systolic pressure) with fractional excretion of uric acid (FEua) and uric acid clearance rate (Cur). Independent T test was used to compare the differences of blood pressure values in FEua1 (FEua< 6.0%) and FEua2 (FEua≥6.0%) or Cur1 (Cur < 6.2 ml/min/1.73 m2) and Cur2 (Cur ≥ 6.2 ml/min/1.73m2) groups according to the median of FEua or Cur, respectively.

RESULTS

After adjusting for confounding factors, multiple linear regression analysis showed that FEua was positively associated with the mMDP and nMDP, Cur was positively associated with CV of dMSP. Levels of mMDP and nMDP in FEua1 group was lower than that in FEua2 group (both P < 0.05), level of CV of dMSP in Cur2 group were higher than that in Cur1 group (P < 0.01).

CONCLUSIONS

We demonstrated that there is a positive correlation of FEua with morning and night mean diastolic pressure separately and Cur is positively related to CV of dMSP in CKD population. Monitoring the trend of urinary uric acid, may have a role in the early detection for hypertension or relative risks in the population of CKD.

The interactive effect of habitual midday napping and nighttime sleep duration on impaired fasting glucose risk in healthy adolescents

OBJECTIVES

To investigate the association between habitual midday napping and impaired fasting glucose (IFG), and the interactive effect of napping and time in bed (TIB) at night on IFG among healthy adolescents.

METHODS

The sample comprised 625 early adolescents (12.26 ± 0.63 years old) who self-reported good health status from Jintan, China. Midday napping and nighttime sleep were measured using the Youth Self-report Sleep Questionnaire. Fasting plasma glucose was dichotomized into normal (<5.6 mmol/L) and impaired (≥5.6 mmol/L) levels. The multivariate random-effect logistic regression examined the nap-glucose relationship and the interaction between nap and TIB. Marginal effects of napping were calculated when TIB was held constant at different values.

RESULTS

Of the participants, 83.20% (n = 520) took naps and 62.28% reported average nap durations ≥31 min in the past month. Moreover, 16% (n = 101) of participants had IFG. After adjusting for covariates, early adolescents who napped 3-4 days/week (OR = 1.72, p < 0.001), 5-7 days/week (OR = 1.34, p = 0.02) or ≥31 min/nap (OR = 1.52, 1.56, p's < 0.05) were associated with increased likelihoods of IFG compared to non-nappers. There was an inverse relationship between TIB and IFG among non-nappers (OR = 0.45, p = 0.03). Interaction analyses also showed significantly increased likelihoods of IFG only among nappers with TIB ≥9 hours.

CONCLUSION

The relationship between midday napping and IFG is dependent on TIB. Midday naps may increase the risk for IFG among early adolescents who have sufficient nighttime sleep. However, further research is needed to confirm our preliminary findings.

A large-scale study reveals 24-h operational rhythms in hospital treatment

We found that orders and initial doses of treatment in the hospital were strongly influenced by time of day, regardless of drug type, diagnosis, or care unit. As the first large-scale account of 24-h rhythms in hospital medicine, this study identifies a potential operational barrier to best clinical care. Clinical decisions should be made around the clock; pain, infection, hypertensive crisis, and other conditions do not occur selectively in the morning. Systemic bias in the timing of medicine may also conflict with circadian biology, which can influence when certain treatments are most effective or safe. Our findings suggest that time of day in hospital operations deserves further consideration.

Hospitals operate 24 h a day, and it is assumed that important clinical decisions occur continuously around the clock. However, many aspects of hospital operation occur at specific times of day, including medical team rounding and shift changes. It is unclear whether this impacts patient care, as no studies have addressed this. We analyzed the daily distribution of ∼500,000 doses of 12 separate drugs in 1,546 inpatients at a major children’s hospital in the United States from 2010 to 2017. We tracked both order time (when a care provider places an electronic request for a drug) and dosing time (when the patient receives the drug). Order times were time-of-day−dependent, marked by distinct morning-time surges and overnight lulls. Nearly one-third of all 103,847 orders for treatment were placed between 8:00 AM and 12:00 PM. First doses from each order were also rhythmic but shifted by 2 h. These 24-h rhythms in orders and first doses were remarkably consistent across drugs, diagnosis, and hospital units. This rhythm in hospital medicine coincided with medical team rounding time, not necessarily immediate medical need. Lastly, we show that the clinical response to hydralazine, an acute antihypertensive, is dosing time-dependent and greatest at night, when the fewest doses were administered. The prevailing dogma is that hospital treatment is administered as needed regardless of time of day. Our findings challenge this notion and reveal a potential operational barrier to best clinical care.

Diurnal Variation of Sitagliptin-Induced Pharmacological Effects in C57BL/6J Mice

Chronopharmacology is the study of the varying responses of drugs to changes in biological timing and endogenous periodicities. The dipeptidyl peptidase-4 inhibitor sitagliptin is a globally prescribed anti-hyperglycemic drug. Although dipeptidyl peptidase-4 inhibitors are usually administered once, the specific intake time is generally not mentioned. Therefore, this study aimed at investigating the diurnal effects of sitagliptin-induced anti-hyperglycemia in high-fat diet (HFD)-induced obesity in mice. Five-week-old male C57BL/6J mice were fed normal (control) diet or HFD for 10 weeks. During the last 2 weeks, the mice were administered saline or sitagliptin (10 mg/kg, per os) in the light or dark phase, respectively. At the end of the experiment, the mice were euthanized after an 18 h fasting period, and plasma and tissue samples (liver, kidney, and epididymal white adipose tissues) were collected, or the oral glucose tolerance test was performed. Sitagliptin administration in the light phase significantly decreased plasma glucose levels, insulin levels, hepatic steatosis, and restored the glucose tolerance compared with the HFD group. In contrast, these parameters remained unchanged in the dark phase-treated mice. Our data therefore suggests that sitagliptin portrays definite chronopharmacology, which may provide valuable information on the importance of drug administration timing for maximum pharmacological effects.