Association of sleep duration with arterial blood pressure profile of gujarati Indian adolescents

Sleep Duration and Blood Pressure in Youth Referred for Elevated Blood Pressure Evaluation

OBJECTIVES

Sleep promotion is not specifically recommended as a target for hypertension management. We examined associations of sleep duration and timing with blood pressure parameters in patients referred to pediatric nephrology clinic for elevated blood pressure evaluation.

METHODS

This is a retrospective study of initial ambulatory blood pressure monitoring data and self-report sleep data collected from patients referred to nephrology clinic for the evaluation of elevated blood pressure. Linear and logistic regression modeling determined associations between sleep exposures (duration and timing) and continuous and dichotomous blood pressure outcomes, respectively, adjusted for age, sex, body mass index, and weekday versus weekend status.

RESULTS

The study sample included 539 patients with mean age 14.6 years and 56% meeting hypertension criteria. Sleep duration averaged 9.1 hours per night. Average timing of sleep onset and offset were 11:06 pm and 8:18 am, respectively. Longer sleep duration was associated with better daytime blood pressure parameters (eg, every extra hour of sleep duration was associated with a reduced odds of wake hypertension [odds ratio, 0.88; 95% CI, 0.79-0.99]). Later sleep onset was associated with worse daytime blood pressure parameters (eg, each additional hour of later sleep onset was associated with higher wake systolic blood pressure index [mean wake blood pressure/95th percentile]) (β = 0.07; 95% CI, 0.02-0.13). Associations were consistent across sex, age, body mass index, and weekday status.

CONCLUSIONS

Longer sleep duration and earlier sleep onset were associated with lower blood pressure. This suggests that sleep optimization may be an important target for intervention in hypertension management.

Sleep Disorders during Adolescence

Sleep disorders during adolescence period increase each year and adversely affect the physical and mental health of adolescents. After-school social activities and various work outside the school may cause delays in bedtime. In addition, there can be shifts in the circadian rhythm due to a number of biological changes seen in the transition to adolescence, which can result in a wide range of sleep problems, such as not being able to fall asleep at night, difficulty waking up in the morning, daytime sleepiness, sleep deprivation and deterioration in sleep quality. It is important to know the causes of sleep disorders, possible effects on physical health and mental health, and protective and risk-forming factors seen in adolescent period; to intervene in these disorders and to develop preventive measures. Preventive measures, such as increasing awareness about sleep disorders in adolescents, informing families and adolescents about the issue, and organizing school start-up times for this age group, may contribute significantly to solving this important issue, which has increased year-to-year.

The Association of Sleep Duration and Quality with Heart Rate Variability and Blood Pressure

BACKGROUND

The current study was conducted to evaluate the relation of sleep duration and quality with blood pressure (BP) and heart rate variability (HRV).

MATERIALS AND METHODS

This cross-sectional study was carried out in 2017 among 260 staff of a university hospital in Isfahan, Iran. They were selected by multi-stage random method from different wards. Time domain spectral analysis was used to measure a number of HRV parameters. The long-term components of the HRV were estimated using the standard deviation of the normal-to-normal interval (SDNN). The square root of the mean squared differences of successive NN intervals (RMSSD) was calculated by statistical time domain measurements; SNN50, and PNN50 were measured. Pittsburg sleep quality index (PSQI) questionnaire was used to assess sleep quality.

RESULTS

Higher PSQI score correlated with lower SDANN rise (OR=0.92). Fairly bad to very good subjective sleep quality had association with lower SDANN (OR=0.43). Very high sleep latency to very low sleep latency ratio had association with lower SDANN (OR=0.39) and lower PNN50 (OR= 0.44). Sleep duration and HRV parameters had no significant association. Fairly bad sleep efficiency to very good sleep efficiency ratio was correlated with lower SDANN (OR= 0.29). Very high daytime dysfunction to very low daytime dysfunction ratio had correlation with lower SDANN (OR=0.35). Very bad compared to very good subjective sleep quality had significant correlation with higher Heart rate (HR) (B=0.03). Very high sleep latency compared to no sleep latency was associated with higher HR (B=4.74). Very high compared to very low amount of sleep disturbances correlated with higher SBP levels (B=15.2). Using sleep medication less than once a week compared with no history of taking such drugs was associated with higher HR (B=16.4).

CONCLUSION

Our findings showed that poor sleep quality are adversely associated with HRV, HR and BP. This finding should be considered in clinical and preventive recommendations.

EVIDENCE OF THE ASSOCIATION BETWEEN SLEEP DURATION AND BLOOD PRESSURE IN ADOLESCENTS: A SYSTEMATIC REVIEW

OBJECTIVE

To review the epidemiological evidence of the association between sleep duration and blood pressure in adolescents.

DATA SOURCES

We performed a systematic review of observational studies in Medline, Scopus, Lilacs, Web of Science, Science Direct databases and Virtual Libraries in English, Spanish and Portuguese published until September 2018. Studies were selected first by title and abstract, then by complete reading, according to the eligibility criteria. The reference list of selected articles was evaluated in order to retrieve relevant studies.

DATA SYNTHESIS

Initially, 1,455 articles were retrieved. After exclusion due to duplicity or not meeting the eligibility criteria, 13 articles were included in the review. Studies varied greatly in sample size (143 to 6,940 patients), methods of measuring blood pressure and sleep duration, cutoff points, categorization and adjustment of variables. The main evidence from the studies is that short sleep duration is associated with high blood pressure in adolescence, although the presence of association between high blood pressure and long sleep duration is possible, but not clear in the literature.

CONCLUSIONS

Sleep duration, especially short duration, is associated with high blood pressure in adolescents. Such evidence draws attention to implications on cardiovascular health in this age group.

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.

Sugar-sweetened beverages and school students' hypertension in urban areas of Nanjing, China

Literature showed that sugar-sweetened beverages (SSBs) could increase the risk of developing hypertension in school students, but there is no reported evidence from China yet, so this study aims to investigate the association of the SSBs consumption and school students' hypertension in urban areas of Nanjing, China. A cross-sectional survey was conducted among primary and junior high school students selected from 32 primary schools and 16 junior high schools using a multi-stage random sampling method, with a total number of 10,091 participants involved. The mean age of Grade 4 is 9.04 ± 0.38, while the mean age of Grade 7 is 12.03 ± 0.41. Blood pressure was measured and SSBs consumption was reported using a validated questionnaire. The overall prevalence of hypertension was 4.5% among the participants. After adjustment for school, parental education, physical activity, diet intake including meat and snacks, participants who had an experience of SSBs intake were at a higher risk of developing hypertension (odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.15, 1.70) compared with those who had no experience of SSBs intake. A significant association between the consumption of SSBs and hypertension was observed among the students who were at a healthy weight (OR = 1.78, 95% CI = 1.20, 2.65), as well as who were overweight or obese (OR = 1.28, 95% CI = 1.01, 1.61). SSBs may play a contributing role in developing childhood hypertension in this population in China, which is of important implications for future population-based childhood hypertension intervention in China and other countries.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

Risk of Obstructive Sleep Apnoea is Associated with Glycaemia Status in South Asian Men and Women in the United States

Aims

To examine the association between glycaemia status and the risk for obstructive sleep apnoea (OSA) in a cohort of South Asians living in the United States.

Methods

A secondary analysis of a community based cohort of 899 participants from the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study. The Berlin Questionnaire was used to screen for OSA.

Results

Almost one in four (24%) South Asians was at high risk for OSA. Compared to the normal glucose tolerance group (18%), high risk of OSA was significantly more likely in the prediabetes (24%) and diabetes (32%) groups (p = .007). More men (28%) than women (18%) were at high risk of OSA. Risk for OSA was also associated with higher haemoglobin A1c values, hypertension, large waist circumference, and BMI > 27.5 kg/m². In a multivariate regression analysis, sleep disordered breathing (SDB) remained significantly associated with higher haemoglobin A1c values, even after controlling for waist circumference and other demographic and clinical factors.

Conclusions

The risk for SDB and OSA was high among South Asian men and women. Given the association between dysglycaemia and risk for OSA, these health issues require simultaneous clinical assessment. Future studies using objective sleep measures such as polysomnography are warranted in the diagnosis and treatment of OSA in the South Asian adult population already at high risk for dysglycaemia.

Effects of Sleep Disorders on Hemoglobin A1c Levels in Type 2 Diabetic Patients

Background:

Studies have reported the presence of sleep disorders in approximately 50–70% of diabetic patients, and these may contribute to poor glycemic control, diabetic neuropathy, and overnight hypoglycemia. The aim of this study was to determine the frequency of sleep disorders in diabetic patients, and to investigate possible relationships between scores of these sleep disorders and obstructive sleep apnea syndrome (OSAS) and diabetic parameters (fasting blood glucose, glycated hemoglobin A1c [HbA1c], and lipid levels).

Methods:

We used the Berlin questionnaire (BQ) for OSAS, the Epworth Sleepiness Scale (ESS), and the Pittsburgh Sleep Quality Index (PSQI) to determine the frequency of sleep disorders and their possible relationships with fasting blood glucose, HbA1c, and lipid levels.

Results:

The study included 585 type 2 diabetic patients admitted to family medicine clinics between October and December 2014. Sleep, sleep quality, and sleep scores were used as the dependent variables in the analysis. The ESS scores showed that 54.40% of patients experienced excessive daytime sleepiness, and according to the PSQI, 64.30% experienced poor-quality sleep. The BQ results indicated that 50.20% of patients were at high-risk of OSAS. HbA1c levels correlated significantly with the ESS and PSQI results (r = 0.23, P < 0.001 and r = 0.14, P = 0.001, respectively), and were significantly higher in those with high-risk of OSAS as defined by the BQ (P < 0.001). These results showed that HbA1c levels were related to sleep disorders.

Conclusions:

Sleep disorders are common in diabetic patients and negatively affect the control of diabetes. Conversely, poor diabetes control is an important factor disturbing sleep quality. Addressing sleep disturbances in patients who have difficulty controlling their blood glucose has dual benefits: Preventing diabetic complications caused by sleep disturbance and improving diabetes control.

Ethnic differences in sleep duration at 5 years, and its relationship with overweight and blood pressure

BACKGROUND

Studies on adult population indicate shorter sleep duration in ethnic minority groups than host populations. We examined ethnic differences in sleep duration and its relationship with overweight and blood pressure (BP) among children living in Amsterdam.

METHODS

Participants include 2384 children (aged 5 years) and their mothers from the Amsterdam-based longitudinal study. Sleep was categorised into short sleep (<10 h/night) and normal sleep (10-11 h/night). Linear regressions ( Β: were used to study association between sleep duration and systolic BP (SBP) and diastolic BP (DBP). Prevalence ratios (PRs) were used to study ethnic differences in sleep duration and its association with overweight and raised BP.

RESULTS

Minority groups reported shorter sleep duration compared to native Dutch, with prevalence ranging from 11.3% in Dutch to 53.1% in Ghanaians. Age-adjusted PRs ranged from 3.38 (95%CI 2.63-4.34) in Moroccans to 4.78 (95%CI 3.36-6.82) in Ghanaian compared with Dutch children. Increased prevalence of overweight was observed among children with short sleep in Dutch and Moroccans only, but this risk was no longer statistically significant after further adjustment for socioeconomic status. Short sleep was not related to SBP and DBP in all groups. No relationship was observed between short sleep and raised BP except for African Surinamese (3.65, 95% CI 1.23-10.8).

CONCLUSION

Like adults, children from ethnic minority populations sleep less hours than Dutch children. Efforts to improve ethnic inequalities in sleep hygiene should also include children at younger age. Associations as reported in adults with overweight and BP could not consistently be replicated in children, however.

Sleep duration and blood pressure: a longitudinal analysis from early to late adolescence

The aim of this study was to evaluate the association between sleep duration and blood pressure using a cross-sectional and longitudinal approach. As part of a population-based cohort, 1403 adolescents were evaluated at 13 and 17 years old. Sleep duration was estimated by the difference between self-reported usual bedtime and wake-up time. Blood pressure was measured using the auscultatory method. Regression coefficients (β) and respective 95% confidence intervals were computed to evaluate the association between sleep duration and blood pressure, using linear regression models adjusted for practice of sports and body mass index at 17 years old. The mean (standard deviation) sleep duration at 13 years old was 9.0 (0.76) h per day, and on average it decreased by 46 min up to 17 years old. The median (25th-75th) systolic blood pressure at 17 years old was 110.0 (103.5-119.0) mmHg in females and 114.0 (106.0-122.0)mmHg in males (P < 0.001); for diastolic blood pressure the values were 66.0 (60.0-71.0) and 69.0 (62.0-75.0) mmHg, respectively (P < 0.001). In cross-sectional analysis, at 17 years old, after adjustment, a positive association was found between sleep duration and blood pressure, significant only for systolic blood pressure among females [β = 0.730 (0.005; 1.455)]. In girls, no significant association was found between sleep duration at 13 years old and blood pressure at 17 years old, but in males an inverse association was found between sleep duration at 13 years old and blood pressure at 17 years old significant only for systolic blood pressure [β = -1.938 (-3.229; -0.647)]. This study found no association between sleep duration at 13 years old and blood pressure at 17 years old in girls, but among males an inverse association was found.

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.

Associations of short sleep duration with prehypertension and hypertension among Lithuanian children and adolescents: a cross-sectional study

Background

Recent epidemiological studies have found that the prevalence of high blood pressure (BP) has significantly increased among children and adolescents. The aim of this study was to examine the associations between short sleep duration and prehypertension and hypertension in Lithuanian children and adolescents aged 12 to 15 years.

Methods

A cross-sectional study was conducted from November 2010 to April 2012. The participants with high BP (≥90th percentile) were screened on two separate occasions. Self-reported sleep duration was evaluated using questionnaires. Data on 6,940 subjects aged 12–15 years were analyzed. Adjusted odds ratios (aORs) with 95% confidence intervals for the associations were estimated using multivariate logistic regression models. Short sleep duration was defined as <8 hours per day (h/day).

Results

The prevalence of prehypertension and hypertension in the current sample was 12.6% and 22.5%, respectively. The percentages of the subjects with sleep durations of <7 (h/day), 7– < 8 h/day, and ≥8 h/day were 8.7%, 21.0%, and 70.3%, respectively. After adjusting for age, sex, body mass index, physical activity, and smoking, significant associations were found between short sleep duration and high BP, including prehypertension (7– < 8 h/day: aOR = 1.77; 95% CI, 1.48–2.12; <7 h/day: aOR = 2.18; 95% CI, 1.70–2.79) and hypertension (7– < 8 h/day: aOR = 1.99; 95% CI, 1.72–2.31; <7 h/day: aOR = 2.28; 95% CI, 1.85–2.80) (all P values <0.001), compared to participants who were sleeping longer (≥8 h/day).

Conclusions

Prehypertension and hypertension were associated with short sleep duration among Lithuanian children and adolescents aged 12 to 15 years.

Blood pressure and its associated factors among primary school children in suburban Selangor, Malaysia: A cross-sectional survey

BACKGROUND

Little is known about the relationship of blood pressure (BP) with adiposity indicators, dietary habits, physical activity, and sleep in school children in Malaysia. We aimed to study about the distribution of BP and its associated factors in primary school children.

MATERIALS AND METHODS

A survey was carried out on a random sample of 335 children in five primary schools. BP was measured with a mercury sphygmomanometer. Anthropometry was done by standard methods. Demographic information, dietary habits, physical activity, and duration of sleep were collected by interviews. World Health Organization classification based on body mass index (BMI) and waist circumference (WC) cut-offs were used to define overweight/obesity. Elevated BP was defined according to US reference standards.

RESULTS

A total 335 children (144 boys and 191 girls) were examined. Their mean age was 9.18 years (standard deviation [SD] = 0.28). Overall mean systolic blood pressure (SBP) and mean diastolic blood pressure (DBP) were 99.32 mmHg (SD = 10.79) and 67.11 mmHg (SD = 10.76), respectively. Mean BMI and WC were 16.39 (SD = 3.58) and 57.77 cm (SD = 8.98), respectively. The prevalence of pre-hypertension was 12.23% (95% confidence intervals [CIs] 8.73, 15.75) and hypertension was 13.4% (95% CIs 9.78, 17.09). Mean SBP and DBP was higher among overweight and obese children than normal children. By multivariate linear regression analyses, BMI (β = 0.250, P = 0.049) and WC (β = 0.308, P = 0.015) were positively associated with SBP; age (β = 0.111, P = 0.017), BMI (β = 0.320, P = 0.012) were positively associated with DBP but total (weekly) hours of sleep (β = -0.095, P = 0.037) was negatively associated with DBP.

CONCLUSION

BP was associated with BMI and WC. Health promotion activities should be initiated in primary schools.

Functional consequences of inadequate sleep in adolescents: a systematic review

During adolescence, changes in sleep patterns due to biological and environmental factors are well documented. Later bedtimes and inadequate sleep, i.e., short and disrupted sleep patterns, insomnia and daytime sleepiness, have become increasingly common. Accumulating evidence suggests that sleep plays a crucial role in healthy adolescent development. This review systematically explores descriptive evidence, based on prospective and cross sectional investigations, indicating that inadequate sleep is associated with negative outcomes in several areas of health and functioning, including somatic and psychosocial health, school performance and risk taking behavior. Findings highlight the need for longitudinal investigations aimed at establishing the underpinnings of these associations and for developing and implementing interventions designed to achieve healthier and more balanced sleep patterns in the adolescent population.

Association between sleep duration and blood pressure in adolescents

In adults, sleep has an important role in the development of cardiovascular diseases. However, in young adolescents, the effect is unclear. The purpose of this cross-sectional study was to evaluate the association between sleep duration and blood pressure (BP) in subjects of 13 years of age. We evaluated 1771 adolescents as part of a population-based cohort (Epidemiological Health Investigation of Teenagers). Sleep duration was estimated based on the difference between self-reported usual bedtimes and wake-up times, and adolescents were classified into three categories: 8.5 h (reference class), >8.5 h and <9.5 h, and 9.5 h. BP was measured using the auscultatory method and was classified as high if the systolic or diastolic BP was 90th percentile according to the American Academy of Pediatrics. To evaluate the association between BP and sleep duration, the odds ratios (ORs) and 95% confidence intervals (95% CIs) were computed by fitting binary logistic regression models with adjustments for caffeine intake and depressive symptoms in females and for caffeine intake and sports activities in males. The mean (s.d.) sleep duration was 9.0 (0.80) h per day. The prevalence of high BP was 32.5%, higher in males (35.3%) than in females (30.1%, P=0.019). After adjustment, in females, a positive association was found between sleep duration and high BP (>8.5 and <9.5 h: OR=1.56, 95% CI 1.07-2.27; 9.5 h: OR=1.83, 95% CI 1.23-2.70). Among males, no significant association was found between sleep duration and BP. Sleep duration was positively associated with BP in both sexes, although after adjustment for potential confounders, this association was significant only for female adolescents.

Association between sleep duration and hypertension among Chinese children and adolescents

BACKGROUND

Short sleep duration was reported to be associated with an increased risk of hypertension among adults. The present study aimed to investigate this association in children and adolescents.

HYPOTHESIS

Short sleep duration is related to higher risk of hypertension among children and adolescents.

METHODS

We conducted a cross-sectional study of 4902 children and adolescents age 5 to 18 years. Blood pressure (BP) was measured at the research center and classified using the population-based percentiles. Sleep duration and related information were determined through questionnaires.

RESULTS

The prevalence of hypertension and prehypertension were 20.3% and 15%, respectively. The median sleep duration was 8.77 ± 1.07 hours (mean ± standard deviation). A short sleep duration (<9 hours) was associated with a higher risk of hypertension when compared with the group sleeping longer (9-10 h), among boys age 11 to 14 years old (OR, 1.5; 95% CI, 1.04-2.15), adjusting for age, body mass index, waist circumference, and physical activity. The linear regression stratified by age indicated that for boys age 11 to 14 years the inverse association existed after adjustment with the coefficients -1.04 mm Hg and -0.55 mm Hg per hour of sleep for systolic BP and diastolic BP, respectively.

CONCLUSIONS

Short sleep duration (<9 h) is independently associated with hypertension among Chinese boys age 11 to 14 years old.