Poor sleep and cardiovascular function in children

Effect of sleep disturbance on biomarkers related to the development of adverse health outcomes: A systematic review of the human literature

Literature suggests that unrestricted and undisturbed sleep is vital for basic human function and performance; however, it is unclear as to what amount of sleep disturbance leads to dysregulation in biomarkers, which may underscore the development of adverse health effects. This systematic review aims to identify the amount of sleep disturbance that contributes to biomarker changes as a potential precursor to the development of adverse health effects. English-language comparative studies available in PubMed, Cochrane Central, EMBASE, and CINAHL databases from 1 January 1980 to 31 July 2021 were searched. Where possible, random-effects meta-analyses were used to examine the effect of sleep disturbances on adverse health effects. The risk of bias of individual studies was assessed using the Cochrane Risk of Bias Tool and the Risk of Bias of Nonrandomised Studies - of Exposures instruments and the certainty of the body of evidence for each outcome was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. The search identified 92 primary studies reporting on blood pressure, hypertension, heart rate, cardiac arrhythmia, cardiac output, waist circumference, cortisol, adrenaline, noradrenaline, immune system markers, glucose, insulin, cholesterol, and triglyceride levels. Although some meta-analyses suggested there may be an association between sleep disturbances and certain outcomes, the certainty in the evidence was very low due to concerns with risk of bias, inconsistency across exposures, populations, and imprecision in the estimates of effects. Further research is needed to explore the point at which types, levels and duration of sleep disturbances may begin to increase the risk of developing adverse health outcomes to inform and tailor health interventions.

Which Is More Important for Health: Sleep Quantity or Sleep Quality?

Sleep is one of the basic physiological processes for human survival. Both sleep quantity and sleep quality are fundamental components of sleep. This review looks at both sleep quantity and sleep quality, considering how to manage the complex but probably unavoidable physiological phenomenon of sleep. The need for sleep has marked variations between individuals, in addition to the effects of variable conditions. Studies on sleep quality started later than those on sleep quantity, beginning in 1989 when Ford and Kamerow revealed that insomnia increases the risk of psychiatric disorders. According to the nationwide research team on the quality of sleep (19FA0901), sleep quality is superior to sleep quantity as an index for assessing sleep, and that restfulness obtained through sleep is a useful index for assessing sleep quality. We should pay more attention to obtaining sleep of good quality (restfulness, no sleepiness, no need for more sleep, sufficient objective sleep depth, etc.), although there have not been enough studies on the associations between sleep quality and health or disorders in children and adolescents. Further studies using the deviation from an individual’s optimal sleep quantity may show us another aspect of the effects of sleep quantity on various life issues.

Gender-Specific Longitudinal Association of Sleep Duration with Blood Pressure among Children: Evidence from CHNS 2004-2015

Purpose

We conducted this study to add the evidence regarding the gender-specific association between sleep duration and blood pressure (BP) in children.

Methods

A secondary analysis was performed among 1000 children aged 7–13 years, who had at least two rounds of survey records in China Health and Nutrition Survey through 2004–2015. Generalized estimating equation was used to explore the gender-specific association of sleep duration with BP. The subgroup analysis was applied in those participants with normal weight.

Results

The time trend of decreasing sleep duration, along with increasing BP level, was observed in each age group during the survey period. Short sleepers (<9 hours per day) have higher level of both systolic BP (SBP) and diastolic BP (DBP) than long sleepers in girls (all p < 0.05). By contrast, only SBP was higher in short sleepers among boys (p < 0.05). There was gender difference in the association between sleep duration and DBP (p for interaction <0.05). The stratification analysis showed that short sleep duration could consistently predict a higher level of diastolic BP (DBP) in both crude (β = 2.968, 95% CI: 1.629, 4.306) and adjusted models (β = 1.844, 95% CI: 0.273, 3.416) only in girls. Sleep duration was also analyzed as continuous variable, and the very similar associations were observed. Moreover, the established associations can be verified among children with normal weight.

Conclusions

There was a time trend of decreasing sleep duration alongside increasing BP among children from 2004 to 2015. Short sleep duration was independently associated with increased DBP; however, only girls were susceptible to the association.

Sleep quality, sleep duration, and their association with hypertension prevalence among low-income oldest-old in a rural area of China: A population-based study

OBJECTIVE

The relationship among sleep quality, sleep duration and hypertension prevalence is controversial in different age groups and genders. This study aimed to investigate sleep quality, sleep duration and their association with hypertension prevalence among low-income oldest-old in a rural area of China.

METHODS

A cross-sectional survey was conducted in a representative sample of 1066 adults aged 80-99 years in 2017. Logistic regression analysis was performed.

RESULTS

Among males, sleep durations of <6 h and 6-<7 h were significantly associated with hypertension prevalence, with odds ratios (ORs) of 3.15 (95% confidence interval (CI) 1.37 to 7.23) and 2.38 (95% CI 1.22 to 4.63), respectively. Among females, only the sleep duration of <6 h was associated with increased OR of hypertension of 3.49 (95% CI 1.50 to 8.09). Poor sleep quality was associated with hypertension for both genders (OR_men 1.67, 95% CI 1.12 to 2.49; OR_women 1.91, 95% CI 1.29 to 2.82). For women, a combination of poor sleep quality and any group of sleep duration, except for 7-<8 h, was associated with higher hypertension prevalence. For men, only the combination of poor sleep quality and short sleep duration (<7 h) was associated with high hypertension prevalence.

CONCLUSION

Short sleep duration and poor sleep quality are associated with hypertension prevalence of oldest-old. The prevention of hypertension in older adults should be investigated from the perspective of sleep improvement.

Sleep duration and blood pressure in children: Analysis of the pan-European IDEFICS cohort

The present study aims to examine the cross-sectional and longitudinal association between self-reported nocturnal sleep duration, blood pressure, and hypertension in European children, aged 2-9.9 years, participating in the IDEFICS project. Blood pressure (BP) and the main anthropometric indices were measured according to standardized procedures. Childhood elevated BP and hypertension were defined according to the European Society of Hypertension Guidelines for children and adolescents. Parents reported lifestyle and socio-demographic data. Nocturnal sleep duration was assessed as part of a parental 24-h recall and categorized as follows: (a) ≤9 hours/night; (b) >9 hours to ≤10 hours/night; (c) >10 hours to ≤11 hours/night; and (d) >11 hours/night. A complete set of variables included in the present analysis was provided by 7974 participants (boys/girls = 4049/3925) at the baseline survey (T0). Of them, 5656 were re-examined 2 years later at follow-up (T1). Children reporting shorter sleep duration at T0 had significantly higher BP values (P for trend < 0.001) compared to those who slept more. Prospective analyses showed that shorter sleep duration at baseline predicted, over the 2-year follow-up, higher increases in systolic blood pressure and diastolic blood pressure, after adjustment for age, sex, country of origin, BMI z-score, parental education, physical activity, screen time, and T0 value of the examined outcome variables (P for trend < 0.001). Our findings reveal that shorter sleep duration is associated with higher BP in childhood, suggesting that sleep may be a potential risk factor for hypertension later in life.

Association between sleep duration and high blood pressure in adolescents: a systematic review and meta-analysis

CONTEXT

Sleep has been assessed as a risk factor for health consequences. Among adults, excessively longer and shorter sleep durations are associated with high blood pressure (BP), but knowledge of the association between sleep duration and high BP among adolescents is limited.

OBJECTIVES

To estimate the associations between sleep duration and high BP in adolescents.

METHODS

PubMed, Web of Science, and Cochrane databases were searched for eligible publications up until 20 November 2017. This study reviewed the reference lists from retrieved articles to search for relevant studies. Pooled odds ratios (ORs) were calculated using a random-effects meta-analysis. Sub-group and sensitivity analyses were conducted to identify heterogeneity. Publication bias was evaluated using Egger's test.

RESULTS

Seven studies involving 21,150 participants were included, with ages ranging from 10-18 years. For primary analysis, compared with the reference sleep duration, the pooled OR for high BP was 1.51 (95% confidence interval [CI] = 1.04-2.19) for the short sleep duration overall. For long sleep duration, the pooled OR was 1.04 (95% CI = 0.78-1.38). Further sub-group analysis showed that short sleep duration had a higher risk of incident high BP in males (OR = 1.55, 95% CI = 1.24-1.93) than in females (OR = 1.23, 95% CI = 0.47-3.22).

CONCLUSIONS

Among adolescents, and particularly male adolescents, short sleep duration may be a risk factor for high BP. More attention should be given to this lifestyle factor.

Objective Sleep Characteristics and Cardiometabolic Health in Young Adolescents

: media-1vid110.1542/5778442247001PEDS-VA_2017-4085Video Abstract BACKGROUND AND OBJECTIVES: Shorter sleep duration is associated with childhood obesity. Few studies measure sleep quantity and quality objectively or examine cardiometabolic biomarkers other than obesity.

METHODS

This cross-sectional study of 829 adolescents derived sleep duration, efficiency and moderate-to-vigorous physical activity from >5 days of wrist actigraphy recording for >10 hours/day. The main outcome was a metabolic risk score (mean of 5 sex-specific z-scores for waist circumference, systolic blood pressure, high-density lipoprotein cholesterol scaled inversely, and log-transformed triglycerides and homeostatic model assessment of insulin resistance), for which higher scores indicate greater metabolic risk. Secondary outcomes included score components and dual-energy radiograph absorptiometry fat mass. We measured socioeconomic status, race and/or ethnicity, pubertal status, and obesity-related behaviors (television-viewing and fast food and sugar-sweetened beverage consumption) using questionnaires.

RESULTS

The sample was 51.5% girls; mean (SD) age 13.2 (0.9) years, median (interquartile range) sleep duration was 441.1 (54.8) minutes per day and sleep efficiency was 84.0% (6.3). Longer sleep duration was associated with lower metabolic risk scores (-0.11 points; 95% CI: -0.19 to -0.02, per interquartile range). Associations with sleep efficiency were similar and persisted after adjustment for BMI z score and physical activity, television-viewing, and diet quality. Longer sleep duration and greater sleep efficiency were also favorably associated with waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, and fat mass.

CONCLUSIONS

Longer sleep duration and higher sleep efficiency were associated with a more favorable cardiometabolic profile in early adolescence, independent of other obesity-related behaviors. These results support the need to assess the role of sleep quantity and quality interventions as strategies for improving cardiovascular risk profiles of adolescents.

Self-reported nocturnal sleep duration and glycosylated hemoglobin A in the Study of Cardiovascular Risks in Adolescents (ERICA)

OBJECTIVE

At present, epidemiologic studies regarding the relationship between sleep duration and glucose metabolism in adolescents are scarce. The objective was to investigate the association between self-reported nocturnal sleep duration and glycosylated hemoglobin A in 12- to 17-year-old Brazilian adolescents.

PATIENTS/METHODS

A school-based multicenter cross-sectional study was carried out in private and public schools from 273 municipalities with more than 100,000 inhabitants. The final sample comprised 24,923 adolescents. A self-administered questionnaire was used. Blood tests included glucose, insulin, glycosylated hemoglobin A and serum lipids. Age, sex, skin color, school type, body mass index (BMI), physical activity, and Brazilian regions were studied as possible effect modifiers and/or confounders using linear regression.

RESULTS

A significant positive association was found between more than 12 h of nocturnal sleep and glycosylated hemoglobin A in two Brazilian regions: Southeast and South, even after adjustment for age, sex, skin color, and BMI (coefficients of 0.142 and 0.339, respectively). No association was found with nocturnal sleep duration <7 h.

CONCLUSION

Notably, a significant positive relationship was found between more than 12 h of nocturnal sleep duration and glycosylated hemoglobin A in two Brazilian regions. The specific pubertal sleep curtailment can be a compensatory mechanism for dealing with the insulin resistance during adolescence. Those that escape from this regulatory strategy and sleep longer than the adequate duration, break down this balance and tend to damage their glucose metabolism. To our knowledge, this is the first large scale study, of the association between sleep duration and glucose metabolism in adolescents.

The effect of sleep duration and sleep quality on hypertension in middle-aged and older Chinese: the Dongfeng-Tongji Cohort Study

OBJECTIVE

To examine the independent and combined associations of sleep duration and sleep quality with hypertension in a middle-aged and older Chinese population.

METHODS

We included 21,912 individuals aged 62.2 years at baseline from September 2008 to June 2010, and they were followed until October 2013. Sleep duration was self-reported and sleep quality was evaluated with questions designed according to the Pittsburgh Sleep Quality Index. Hypertension was defined as blood pressure ≥140/90 mmHg, or self-reported physician diagnosis of hypertension, or self-reported current use of antihypertensive medication.

RESULTS

In the cross-sectional analyses, the odds ratio of hypertension prevalence was significantly elevated (OR = 1.13, 95% CI = 1.03-1.24) in those who slept less than 7 h after adjusting for sex, age, body mass index, midday napping, cigarette smoking and sleep quality. It was particularly evident among males (OR = 1.19, 95% CI = 1.01-1.40) and individuals who were thin (OR = 2.00, 95% CI = 1.01-3.93) with full adjustment. The association was also found for sleep duration of 9∼<10 h after adjusting various covariates (OR = 1.14, 95% CI = 1.04-1.27). In addition, impaired sleep quality was only associated with hypertension in obese individuals (OR = 1.25, 95% CI = 1.02-1.50), not in other subgroups. However, no significant association was detected in any category of sleep duration or sleep quality in all models in the prospective analyses, and the results remained unchanged in the subgroup analyses of sex, age and body mass index.

CONCLUSIONS

The results of this study provide limited support for association of sleep duration and sleep quality with hypertension in middle-aged and older Chinese. Further studies are needed to confirm the results.

Inverse Relationship between Sleep Duration and Cardio-Ankle Vascular Index in Children

AIM

Poor sleep has been shown to be associated with the development of cardiovascular risk factors, such as obesity, in both adults and children. This study aimed to investigate the relationship between sleep duration and arterial stiffness indices in Japanese children and early adolescents.

METHODS

The data on 102 students (56 males, 46 females; mean age, 11.9±1.8 years) were analyzed. As non-invasive arterial stiffness parameters, the cardio-ankle vascular index (CAVI) and heart-ankle pulse wave velocity (haPWV) were evaluated. Their students' sleep habits (bedtime and wake times on a usual weekday) were investigated using questionnaires, and based on these, their sleep durations were calculated.

RESULTS

The CAVI values in the males and females were 4.8±0.9 and 4.7±0.9 (arbitrary unit), respectively. haPWV values in the males and females were 5.5±0.6 and 5.4±0.6 m/s, respectively. Sleep duration in the males, but not in the females, was negatively correlated with CAVI (r=－0.356) and haPWV (r=－0.356), suggesting that students with short sleep duration could have increased arterial stiffness. After adjusting for confounders, such as age, sex, systolic blood pressure, heart rate, adiposity, and physical fitness, the correlation of sleep duration with CAVI, but not with haPWV, was still significant (partial r=－0.253, p＜0.05).

CONCLUSION

Our findings suggest that shorter sleep duration influences arterial stiffening even in childhood.

Children's Autonomic Nervous System Reactivity Moderates the Relations between Family Adversity and Sleep Problems in Latino 5-Year Olds in the CHAMACOS Study

Sleep problems are common for young children especially if they live in adverse home environments. Some studies investigate if young children may also be at a higher risk of sleep problems if they have a specific biological sensitivity to adversity. This paper addresses the research question, does the relations between children’s exposure to family adversities and their sleep problems differ depending on their autonomic nervous system’s sensitivity to challenges? As part of a larger cohort study of Latino, low-income families, we assessed the cross-sectional relations among family demographics (education, marital status), adversities [routines, major life events (MLE)], and biological sensitivity as measured by autonomic nervous system (ANS) reactivity associated with parent-rated sleep problems when the children were 5 years old. Mothers were interviewed in English or Spanish and completed demographic, family, and child measures. The children completed a 15-min standardized protocol while continuous cardiac measures of the ANS [respiratory sinus arrhythmia (RSA), preejection period (PEP)] were collected during resting and four challenge conditions. Reactivity was defined as the mean of the responses to the four challenge conditions minus the first resting condition. Four ANS profiles, co-activation, co-inhibition, reciprocal low RSA and PEP reactivity, and reciprocal high RSA and PEP reactivity, were created by dichotomizing the reactivity scores as high or low reactivity. Logistic regression models showed there were significant main effects for children living in families with fewer daily routines having more sleep problems than for children living in families with daily routines. There were significant interactions for children with low PEP reactivity and for children with the reciprocal, low reactivity profiles who experienced major family life events in predicting children’s sleep problems. Children who had a reciprocal, low reactivity ANS profile had more sleep problems if they also experienced MLE than children who experienced fewer MLE. These findings suggest that children who experience family adversities have different risks for developing sleep problems depending on their biological sensitivity. Interventions are needed for young Latino children that support family routines and reduce the impact of family adversities to help them develop healthy sleep practices.

Trajectories of sleep and cardiac sympathetic activity indexed by pre-ejection period in childhood

Fragmented and insufficient sleep has been implicated in disrupted autonomic nervous system activity during resting state conditions in typically developing children. Towards explication of these relations over development, the current study tested reciprocal relations between the development of sleep parameters (efficiency, duration, latency) and cardiac sympathetic nervous system (SNS) activity indexed by pre-ejection period (PEP) during waking-resting state conditions throughout middle and late childhood. Whether sleep derives changes in PEP or vice versa was examined. A longitudinal design was employed and latent growth modelling was used to examine the research questions. During the first assessment, 282 children aged 9.44 years (65% European American, 35% African American) participated. Two more assessments followed, with a 1-year lag between consecutive study waves. Sleep was examined with 7 nights of actigraphy in the child's home. Controlling for many potential confounds (sex, race/ethnicity, body mass index and family socioeconomic status), higher sleep efficiency and more sleep minutes predicted increases in PEP (less SNS activity) over 3 years. PEP did not predict changes in sleep efficiency or duration over time and there were no significant effects for sleep latency. Findings highlight the probable direction of effects between these two key bioregulatory systems. High levels of cardiac SNS activity are associated with many negative health outcomes, and thus these findings may have important implications.

Role of sleep quality in the metabolic syndrome

Emerging evidence has assigned an important role to sleep as a modulator of metabolic homeostasis. The impact of variations in sleep duration, sleep-disordered breathing, and chronotype to cardiometabolic function encompasses a wide array of perturbations spanning from obesity, insulin resistance, type 2 diabetes, the metabolic syndrome, and cardiovascular disease risk and mortality in both adults and children. Here, we critically and extensively review the published literature on such important issues and provide a comprehensive overview of the most salient pathophysiologic pathways underlying the links between sleep, sleep disorders, and cardiometabolic functioning.

Relationship between Duration of Sleep and Hypertension in Adults: A Meta-Analysis

OBJECTIVES

Epidemiologic studies have shown that chronic short sleep may be associated with the development of hypertension; however, the results are controversial. This meta-analysis was conducted to determine whether the duration of sleep is associated with hypertension.

METHODS

Reference databases (PubMed, EmBase, the Cochrane Library, Chinese Biological Medicine database) were searched for studies related to sleep duration and hypertension. Sleep duration categories (≤ 5 h, 6 h, 7 h, 8 h, ≥ 9 h) and prevalence or incidence of hypertension in each sleep category were extracted. A general analysis and subgroup analyses stratified by gender, age, study design, and different definitions of sleep duration were conducted to evaluate the relationship between sleep duration and hypertension.

RESULTS

Thirteen articles out of a total of 1,628 articles involving 347,759 participants met the inclusion criteria. A U-shaped change in pooled odds ratios (ORs) for hypertension due to the change of sleep duration was observed. The unadjusted OR for hypertension of individuals who slept ≤ 5 h vs. 7 h was 1.61, 95% CI = 1.28-2.02; those who slept ≥ 9 h vs. 7 h was 1.29, 95% CI = 0.97-1.71. The pooled ORs were still significant after adjusted by age and gender. Women deprived of sleep (sleep time ≤ 5 h vs. 7 h, OR = 1.68, 95% CI = 1.39-2.03) had a higher risk of hypertension than men (OR = 1.30, 95% CI = 0.93-1.83).

CONCLUSION

Excessively longer and shorter periods of sleep may both be risk factors for high blood pressure; these associations are stronger in women than men.

Sleep characteristics and cardiovascular risk in children and adolescents: an enumerative review

Cardiovascular risk factors develop in childhood and adolescence. This enumerative review addresses whether sleep characteristics, including sleep duration, continuity, quality, and daytime sleepiness, are associated with cardiovascular risk factors in young people. Thirty-nine studies were identified, which examined the following risk factors: metabolic syndrome, glucose and insulin, lipids, blood pressure, and cardiovascular responses to psychological stressors. Due to the availability of other reviews, 16 longitudinal studies of obesity published in 2011 and later were also included in this report. Excluded from the review were studies of participants with suspected or diagnosed sleep disorders and reports from sleep deprivation experiments. Combining studies, evidence was strongest for obesity, followed by glucose, insulin, blood pressure (especially ambulatory blood pressure), and parasympathetic responses to psychological stressors. There was little evidence for metabolic syndrome cluster, lipids, and blood pressure responses to psychological stressors. The more positive associations were obtained for studies that incorporated objective measures of sleep and that included adolescents. The foundational evidence is almost entirely cross-sectional, except for work on obesity. In summary, available evidence suggests that the associations between sleep characteristics and cardiovascular risk vary by risk factor. It is time to conduct studies to determine antecedent and consequent relationships, and to expand risk factors to include markers of inflammation.

Sleep characteristics, body mass index, and risk for hypertension in young adolescents

Inadequate sleep has been identified as a risk factor for a variety of health consequences. For example, short sleep durations and daytime sleepiness, an indicator of insufficient sleep and/or poor sleep quality, have been identified as risk factors for hypertension in the adult population. However, less evidence exists regarding whether these relationships hold within child and early adolescent samples and what factors mediate the relationship between sleep and risk for hypertension. Using data from the Study of Early Child Care and Youth Development, the present study examined body mass index (BMI) as a possible mediator for the effects of school-night sleep duration, weekend night sleep duration, and daytime sleepiness on risk for hypertension in a sample of sixth graders. The results demonstrated gender-specific patterns. Among boys, all three sleep characteristics predicted BMI and yielded significant indirect effects on risk for hypertension. Oppositely, only daytime sleepiness predicted BMI among girls and yielded a significant indirect effect on risk for hypertension. The findings provide clarification for the influence of sleep on the risk for hypertension during early adolescence and suggest a potential need for gender-specific designs in future research and application endeavors.

The associations between adolescent sleep, diurnal cortisol patterns and cortisol reactivity to dexamethasone suppression test

Information on the associations between objectively measured sleep and hypothalamic-pituitary-adrenal axis function in early adolescence is scarce. We examined associations between average sleep duration and quality (sleep efficiency and wake after sleep onset) over 8 days with actigraphs and (1) diurnal cortisol patterns and (2) cortisol reactivity to a low-dose (3 μg/kg) overnight dexamethasone suppression test (DST) in a birth cohort born in 1998 (N=265 participants, mean age 12.3 years, SD=0.5). We also explored (3) if sleep duration and quality were affected the nights after the DST exposure. Cortisol was measured during 2 days, and participants were exposed to dexamethasone in the evening of first day. In boys, short sleep duration was associated with higher cortisol upon awakening and lower cortisol awakening response (CAR; P<0.05 and P<0.01). Long sleep duration in boys associated with higher CAR (P<0.02). Lower sleep quality in boys associated with lower CAR, but fell slightly short of significance (P<0.06). In girls, no significant associations were detected. Sleep quantity and quality were not associated with responses to the DST. There were no effects of DST on sleep (P>0.15 in between-subject analyses). The average sleep patterns showed associations with diurnal cortisol patterns during early adolescence, but only in boys. Sleep was not associated with cortisol reactivity to DST and the exogenous corticosteroid exposure did not affect sleep significantly.

A review of evidence for the link between sleep duration and hypertension

There are lines of evidence from experimental sleep deprivation studies, population-based epidemiological studies, and an interventional study that point to the potential efficacy of adequate quality sleep to prevent and treat hypertension. Experimental sleep restriction has been shown to raise blood pressure and heart rate. Insufficient sleep on a chronic basis can raise average 24-hour blood pressure and lead to structural adaptations that entrain the cardiovascular system to operate at an elevated blood pressure equilibrium and increase the risk for hypertension. Disruptions in the timing and duration of sleep could also disrupt circadian rhythmicity and autonomic balance, which can increase the prevalence of the nondipping pattern, disturb diurnal rhythm of cardiac output, and increase blood pressure variability. Short sleep duration has been found to be associated with higher blood pressure and hypertension in both cross-sectional and longitudinal epidemiological studies. The association appears stronger in middle-aged adults and in women. Experimental sleep extension has been shown to significantly reduce blood pressure in individuals with prehypertension or stage 1 hypertension. The observed association between sleep duration and hypertension raises the hypothesis that interventions to extend sleep and improve sleep quality could serve as effective primary, secondary, and tertiary preventive measures for hypertension.

Sleep efficiency and nocturnal hemodynamic dipping in young, normotensive adults

Blunted dipping of nocturnal systolic arterial pressure (SAP) and heart rate (HR) are independent risk factors for hypertension and all-cause mortality. While several epidemiological studies report a significant association between short sleep duration and hypertension, associations between sleep efficiency and the nocturnal drop of SAP remain controversial. Moreover, relations between sleep efficiency and HR diurnal patterns have been overlooked. We hypothesized that low sleep efficiency (<85%) would be associated with blunted nocturnal SAP and HR dipping. Twenty-two normotensive subjects (13 men, 9 women; age: 18–28 yr) wore an actigraphy watch for 7 days and nights, and an ambulatory blood pressure monitor for 24 h on a nonactigraph night. There were no differences in age, sex, body mass index, mean sleep time, number of awakenings, or 24-h blood pressure between the low ( n = 12) and high ( n = 10) sleep efficiency groups. However, the low sleep efficiency subjects demonstrated a blunted dip of nocturnal SAP (10 ± 1% vs. 14 ± 1%, P = 0.04) and HR (12 ± 3% vs. 21 ± 3%, P = 0.03) compared with the high sleep efficiency group. The low sleep efficiency group also demonstrated a higher mean nocturnal HR (63 ± 2 vs. 55 ± 2 beats/min; P = 0.02). These findings support growing evidence that sleep efficiency, independent of total sleep time, may be an important cardiovascular risk factor.

Low physical activity level and short sleep duration are associated with an increased cardio-metabolic risk profile: a longitudinal study in 8-11 year old Danish children

Background

As cardio-metabolic risk tracks from childhood to adulthood, a better understanding of the relationship between movement behaviors (physical activity, sedentary behavior and sleep) and cardio-metabolic risk in childhood may aid in preventing metabolic syndrome (MetS) in adulthood.

Objective

To examine independent and combined cross-sectional and longitudinal associations between movement behaviors and the MetS score in 8-11 year old Danish children.

Design

Physical activity, sedentary time and sleep duration (seven days and eight nights) were assessed by accelerometer and fat mass index (fat mass/height²) was assessed using Dual-energy X-ray absorptiometry. The MetS-score was based on z-scores of waist circumference, mean arterial blood pressure, homeostatic model assessment of insulin resistance, triglycerides and high density lipoprotein cholesterol. All measurements were taken at three time points separated by 100 days. Average of the three measurements was used as habitual behavior in the cross-sectional analysis and changes from first to third measurement was used in the longitudinal analysis.

Results

723 children were included. In the cross-sectional analysis, physical activity was negatively associated with the MetS-score (P<0.03). In the longitudinal analysis, low physical activity and high sedentary time were associated with an increased MetS-score (all P<0.005); however, after mutual adjustments for movement behaviors, physical activity and sleep duration, but not sedentary time, were associated with the MetS-score (all P<0.03). Further adjusting for fat mass index while removing waist circumference from the MetS-score rendered the associations no longer statistically significant (all P>0.17). Children in the most favorable tertiles of changes in moderate-to-vigorous physical activity, sleep duration and sedentary time during the 200-day follow-up period had an improved MetS-score relative to children in the opposite tertiles (P = 0.005).

Conclusion

The present findings indicate that physical activity, sedentary time and sleep duration should all be targeted to improve cardio-metabolic risk markers in childhood; this is possibly mediated by adiposity.

Sleep duration and its association with ambulatory blood pressure in a school-based, diverse sample of adolescents

BACKGROUND

Evidence is accumulating that sleep duration is related to blood pressure (BP) and hypertensive status, but the strength of the association varies by age, and findings are inconsistent for adolescents. This cross-sectional study tested the hypothesis that sleep duration, both during the night and during naps, would be negatively associated with ambulatory systolic BP (SBP) and diastolic BP (DBP) measured over 24 hours in adolescents.

METHODS

In this ethnically diverse (37% non-Hispanic black, 31% Hispanic, 29% non-Hispanic white, 3% other), school-based sample of 366 adolescents aged 11-16 years, ambulatory BP was measured every 30 minutes for 24 hours on a school day; actigraphy was used to measure sleep duration. Covariables included demographic factors, anthropometric indices, physical activity, and position and location at the time of each BP measurement. Mixed models were used to test day and night sleep duration as predictors of 24-hour SBP and DBP, controlling for covariables.

RESULTS

The mean sleep duration was 6.83 (SD = 1.36) hours at night, and 7.23 (SD = 1.67) hours over 24 hours. Controlling for duration of sleep during the day and covariables, each additional hour of nighttime sleep was associated with lower SBP (-0.57; P < 0.0001); controlling for nighttime sleep duration and covariables, each additional hour of daytime sleep was associated with lower SBP (-0.73; P < 0.001) and lower DBP (-0.50; P < 0.001).

CONCLUSIONS

Longer sleep duration was significantly associated with lower ambulatory SBP and DBP in adolescents. The findings have potential implications for cardiovascular health in this age group.

Acute and chronic effects of sleep duration on blood pressure

OBJECTIVE

To evaluate the association between ambulatory blood pressure (ABP) and sleep duration as measured by 7-day sleep diary and nocturnal polysomnography in normal-weight adolescents without significant obstructive sleep apnea.

METHODS

Subjects aged 10 to 17.9 years with an obstructive apnea hypopnea index <5 underwent polysomnography for 9.5 hours and 24-hour ABP monitoring commencing at noon on the same day. ABP was divided into prepolysomnography, in bed during polysomnography, and postpolysomnography periods for separate analyses. Sleep duration (SpD7) was obtained from a 7-day sleep diary, reflecting the sleep pattern in the week before admission. Total sleep time (TST) and sleep efficiency (SpE) were obtained from polysomnography.

RESULTS

A total of 143 adolescents participated. SpD7 was inversely associated with systolic blood pressure (SBP) in prepolysomnography, in-bed, and postpolysomnography periods (all β = -2 mm Hg) and with diastolic blood pressure (DBP) in prepolysomnography and in-bed periods (all β = -1 mm Hg). TST was inversely associated with SBP in the postpolysomnography period (β = -1.5 mm Hg). SpE was inversely associated with SBP in in-bed period (β = -0.1 mm Hg) and with DBP in in-bed (β = -0.1 mm Hg) and postpolysomnography (β = -0.2 mm Hg) periods. Neither TST nor SpE was associated with SBP and DBP in prepolysomnography period.

CONCLUSIONS

Short sleep duration as reflected by 7-day sleep diary was associated with higher blood pressure in normal-weight adolescents. Occasional adequate sleep may partially ameliorate the risk of high blood pressure but may not completely reverse the effect of long-term sleep insufficiency.

Relations between daytime pre-ejection period reactivity and sleep in late childhood

The sympathetic nervous system and children's sleep serve critical arousal regulation functions. Shortened pre-ejection period, a reliable indirect index of greater sympathetic nervous system activity, has been associated with reduced sleep duration and quality in adults, but limited evidence exists in children regarding associations between pre-ejection period and sleep. We examined relations between pre-ejection period reactivity in response to a laboratory-based stressor and multiple parameters of actigraphy-based sleep duration and quality in children. The sample included 123 boys and 112 girls [mean age = 11.31 years, standard deviation (SD) = 0.63 years]. Controlling for body mass index, sex and pre-ejection period baseline, increased sympathetic nervous system reactivity, indexed by a lower level of pre-ejection period during the challenge than the baseline, was associated with worse sleep quality indicated by lower sleep efficiency, greater sleep activity and greater long wake episodes. The findings add to a small literature on relations between sympathetic nervous system functioning and children's sleep, suggesting that poor sleep quality is related to dysregulation of this stress response system.

Children's sleep and autonomic function: low sleep quality has an impact on heart rate variability

OBJECTIVES

Short sleep duration and poor sleep quality in children have been associated with concentration, problem behavior, and emotional instability, but recently also with disrupted autonomic nervous function, which predicts cardiovascular health. Heart rate variability (HRV) was used as noninvasive indicator of autonomic function to examine the influence of sleep.

DESIGN

Cross-sectional and longitudinal observational study on the effect of sleep on HRV.

PARTICIPANTS

Belgian children (5-11 years) of the ChiBS study in 2010 (N = 334) and 2011 (N = 293).

INTERVENTIONS

N/A.

METHODS

Sleep duration was reported and in a subgroup sleep quality (efficiency, latency, awakenings) was measured with accelerometry. High-frequency (HF) power and autonomic balance (LF/HF) were calculated on supine 5-minute HRV measurements. Stress was measured by emotion and problem behavior questionnaires. Sleep duration and quality were used as HRV predictors in corrected cross-sectional and longitudinal regressions. Stress was tested as mediator (intermediate pathway) or moderator (interaction) in sleep-HRV associations.

RESULTS

In both cross-sectional and longitudinal analyses, long sleep latency could predict lower HF (parasympathetic activity), while nocturnal awakenings, sleep latency, low sleep efficiency, and low corrected sleep duration were related to higher LF/HF (sympathetic/parasympathetic balance). Parental reported sleep duration was not associated with HRV. The significances remained after correction for stress. Stress was not a mediator, but a moderator (enhancer) in the relationship between sleep quality and HRV.

CONCLUSIONS

Low sleep quality but not parent-reported low sleep duration leads to an unhealthier heart rate variability pattern (sympathetic over parasympathetic dominance). This stresses the importance of good sleep quality for cardiovascular health in children.

Time in bed, sleep quality and associations with cardiometabolic markers in children: the Prevention and Incidence of Asthma and Mite Allergy birth cohort study

We investigated associations of time in bed and multiple sleep quality characteristics with cardiometabolic markers in children. Data from the prevention and incidence of asthma and mite allergy study, a population-based prospective birth-cohort study started in 1996-1997 in the Netherlands, were analysed. In total 1481 children aged 11-12 years completed a questionnaire (including questions on sleep) and underwent a medical examination. We measured body mass index, waist circumference, total- and high-density lipoprotein cholesterol, blood pressure and glycated haemoglobin. Results showed that in girls, some sleep characteristics were related to anthropometrics (body mass index, waist circumference) and cholesterol. Girls who had a long time in bed (11-12.5 h) had 0.16 lower body mass index z-score (95% confidence interval -0.31; -0.01) and 0.99 cm smaller waist circumference (95% confidence interval -2.01; -0.13) compared with girls who spent 10-10.5 h in bed. Girls who went to bed late and rose early had 0.16 mm higher total cholesterol (95% confidence interval 0.01; 0.31) and 0.08 mm higher high-density lipoprotein cholesterol (95% confidence interval 0.01; 0.14) than 'early to bed/early rise' girls. Girls with night-time awakenings had 0.14 mm higher total cholesterol (95% confidence interval 0.03; 0.25) than girls without night-time awakenings. Girls who felt sleepy/tired ≥1 day per week had 0.10 mm lower high-density lipoprotein cholesterol (95% confidence interval -0.16; -0.04) and 0.17 mm higher total cholesterol/high-density lipoprotein cholesterol ratio (95% confidence interval 0.02; 0.32) than girls who did not feel sleepy. No associations were found for boys. Sleep characteristics were not related to blood pressure and glycated haemoglobin, and effect sizes of the associations in girls were small. Therefore, we consider it premature to propose that improved sleep could reduce cardiovascular risk during childhood.

Sleep problems and cardiovascular function in children

OBJECTIVE

To assess the associations of sleep problems with 24-hour ambulatory blood pressure and cardiovascular reactivity in children.

METHODS

Sleep problems in 285 term-born, healthy 8-year-olds (mean [standard deviation] = 8.1 [0.3] years) were measured with a parent-rated Sleep Disturbance Scale for Children. Ambulatory blood pressure (n = 241) was measured for 24 hours (41% nonschool days) with an oscillometric device. The children (n = 274) underwent the Trier Social Stress Test for Children during which blood pressure, electrocardiography, and thoracic impedance were recorded and processed offline to give measures of cardiovascular and autonomic function.

RESULTS

No associations were found between sleep problems and 24-hour ambulatory blood pressure. Children with sleep breathing disorders (n = 5) had higher baseline sympathetic vascular activity (p = .014) and higher heart rate (p = .044) and sympathetic cardiac activity (p = .031) in reaction to stress. Children with disorders of excessive somnolence (n = 55) had higher baseline parasympathetic activity (p = .016). None of the associations remained significant after controlling for multiple testing.

CONCLUSIONS

Our results suggest that in a healthy community sample of prepubertal children, sleep problems are not associated with an unhealthy cardiovascular phenotype at this age. However, associations may be underestimated because of the low prevalence of sleep breathing disorders in this sample and may not generalize to older populations.

Subjective sleep complaints are associated with insulin resistance in individuals without diabetes: the PPP-Botnia Study

OBJECTIVE

Sleep disorders and subjective sleep complaints have been associated with increased risk of type 2 diabetes. The evidence with respect to insulin resistance (IR) and insulin secretion in individuals without type 2 diabetes has been scarce and elusive. We examined if subjective sleep complaints and their co-occurrence were associated with IR and insulin secretion in adult women and men without diabetes.

RESEARCH DESIGN AND METHODS

Women (n = 442) and men (n = 354) 18-75 years of age without type 2 diabetes underwent an oral glucose tolerance test (OGTT), with insulin and glucose measured at fasting and at 30 and 120 min. Complaints related to sleep apnea, insomnia, and daytime sleepiness were self-rated with the Basic Nordic Sleep Questionnaire.

RESULTS

In comparison with individuals with no or minor sleep complaints, those with more frequent complaints of sleep apnea, insomnia, and daytime sleepiness were more insulin resistant, as evidenced by higher fasting insulin concentrations and insulin and glucose responses to OGTT, and more frequently had high homeostasis model assessment of IR and low insulin sensitivity index values. The likelihood of being insulin resistant increased significantly and linearly according to the accumulation of co-occurring sleep complaints. These associations changed only a little when adjusted for mediating and confounding factors and for depressive symptoms. Sleep complaints were not associated with indices of deficiency in insulin secretion.

CONCLUSIONS

Subjective sleep complaints were associated with IR. The likelihood of being insulin resistant increased according to accumulation of co-occurring sleep complaints. Sleep complaints were not associated with deficiency in insulin secretion.

Sleep duration and ambulatory blood pressure in black and white adolescents

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