Sleep-disordered breathing, systemic adipokine secretion, and metabolic dysregulation in overweight and obese children and adolescents

Sleep-disordered breathing and cardiometabolic and inflammatory markers in children with overweight/obesity: The role of cardiorespiratory fitness

OBJECTIVES

To investigate the association of sleep-disordered breathing (SDB) severity with cardiometabolic and inflammatory markers independently of the adiposity levels; and to explore the role of cardiorespiratory fitness in these associations in children with overweight/obesity.

METHODS

A total of 109 children aged 8-11 years with overweight/obesity were included in this cross-sectional study. SDB was assessed using a scale of the reduce version of the Paediatric Sleep Questionnaire. Cardiometabolic markers included fasting blood lipids biomarkers (i.e., low- and high-density lipoprotein cholesterol, and triglycerides), blood pressure, insulin, glucose, and the homeostatic model assessment index. Inflammatory markers (i.e., interleukin-6, interleukin-1β, C-reactive protein [CRP], and tumour necrosis factor alpha) were analysed. Cardiorespiratory fitness was assessed by the 20 m shuttle-run test.

RESULTS

No significant associations were found between SDB severity and most of the cardiometabolic markers after correcting for adiposity and multiple comparisons (all p's >0.05). SDB severity was positively related to CRP (β = 0.352, p = 0.002), yet not with the remaining inflammatory markers analysed. The interaction effect of cardiorespiratory fitness presented a positive trend in the association of SDB with CRP (p = 0.1). When stratified analyses by cardiorespiratory fitness levels were conducted, a positive relation was found between SDB and CRP in the low cardiorespiratory fitness group (β = 0.465, p = 0.014), but not in the high cardiorespiratory fitness group (β = 0.236, p = 0.108).

CONCLUSION

SDB severity was positively associated with CRP independently of the adiposity levels, but not with other inflammatory or cardiometabolic risk factors in children with overweight/obesity. Moreover, our results suggest that higher levels of cardiorespiratory fitness may attenuate the adverse effect of SDB severity on systematic inflammation in children with overweight/obesity.

Comparing the Driving Skills of Adolescents with Obstructive Sleep Apnea to Healthy Controls: The Results of a Case-Controlled Observational Study

Auto crashes are a leading cause of death and injury among adolescents. Untreated obstructive sleep apnea (OSA) can cause sleepiness and inattention, which could negatively impact novice drivers, but OSA-related studies have focused on older drivers. This study used a driving simulator to examine whether licensed 16-19-year-old adolescents with OSA have diminished driving skills. Twenty-one adolescents with OSA and twenty-eight without OSA (both confirmed using polysomnography) completed two randomly ordered driving trials in a simulator (with induced distractions versus without). A mixed ANOVA examined the between-subjects effect of the OSA group, the within-subjects effect of the distraction condition, and the group-by-condition interaction effect on the ability to maintain lane position and the frequency of extended eye glances away from the roadway. T-tests were also used to examine group differences in reported sleepiness and inattention during daily life. The distraction task increased extended off-road glances and difficulties maintaining lane position (p < 0.001). However, adolescents with OSA did not display worse eye glance or lane position than controls and there were no significant group-by-condition interactions. Although the groups differed on polysomonographic features, there were also no significant differences in reported sleepiness or inattention. The distraction task negatively impacted both groups of adolescent drivers, but those with OSA did not fare differentially worse. Most adolescents in our study had mild OSA (median obstructive apnea-hypopnea index = 4.4), the most common form in the community. It remains possible that youth with more severe OSA would show increased driving impairment.

Fibroblast growth factor 21 is an independent predictor of prevalent and incident obstructive sleep apnea

Fibroblast growth factor 21 (FGF21) is a metabolic regulator and a potential biomarker of metabolic diseases. Limited data are available on the association between FGF21 and obstructive sleep apnea (OSA), which is considered as a manifestation of metabolic syndrome. In the present cross-sectional and longitudinal analyses, the FGF21 level was associated with OSA. This analysis of two clinical cohorts is the first to show that the FGF21 level increased significantly with OSA severity and was an independent predictor of incident OSA in Chinese adults. The circulating FGF21 level could serve as a potential serum biomarker of OSA and its comorbidities and thus aid risk evaluation and early intervention.

Serum leptin differs in children with obstructive sleep apnea: A meta-analysis and PRISMA compliant article

BACKGROUND

Obstructive sleep apnea (OSA) as an independent cardiovascular risk factor has been proposed, but the mechanisms underlying cardiovascular disease is far from being completely elucidated. Leptin, an inflammatory cytokine produced by adipocytes, contributes to the modulation of metabolism, respiratory control, and inflammation, which are factors associated with cardiovascular disease. Serum levels of leptin in children with OSA have shown conflicting results in previous studies.

METHODS

We performed a meta-analysis to clarify the correlation between leptin expression of the OSA patients following the PRISMA. PubMed, Embase, and Web of Science were systematically searched for relevant studies, and then independently screened by two researchers, and analyzed the data through STATA version 12.0.

RESULTS

In a total of 5 articles including 469 participants, the data analysis showed that serum leptin levels were elevated in children with OSA (MD, 6.36; 95% CI, 0.24-12.49, P < .001), compared to the control group. Subgroup analysis were performed based on body mass index. The results of subgroup analysis demonstrated that the serum leptin concentration was correlated with body mass index in children with OSA (MD, 9.70; 95% CI, 0.22-11.18, P < .001).

CONCLUSIONS

The serum leptin levels were elevated in children with OSA, compared to the control group. It could add to our developing understanding of the pathogenesis and potential treatments for children with OSA, and help us to recognize the relevance of OSA in determining cardiovascular issues among children.

Polysomnographic comparison of sleep in children with obesity and normal weight without suspected sleep-related breathing disorder

Short sleep and obstructive apneas/hypopneas have been shown to be associated with childhood obesity. Still, few studies have compared sleep in children with obesity, without suspected sleep disordered breathing and normal weight peers by objective sleep measures and compared results with subjective parent assessment of sleep. Children with obesity aged 7-13 years (N = 44) and a matched group of normal weight children (N = 42) completed clinical polysomnography (Embla A10 Recording System). Parents scored their children's sleep on the Children's Sleep Habits Questionnaire (CSHQ). Mann-Whitney U tests were used to compare groups. There was a higher obstructive apnea/hypopnea index (AHI) (median obesity = 1.20 vs. median normal  = 0.66; z = -1.33, U = 560.50, p = 0.002) and number of oxygen desaturation events per hour (median obesity = 0.7 vs. median normal  = 0.2; z = -3.45, U = 402.50, p = 0.001) in the children with obesity compared to children with normal weight. The children with obesity had a significantly longer sleep duration (median obesity 8:50 h = vs. median normal = 8:32 h; z = -2.05, U = 687.00, p = 0.041), longer stage N2 sleep (median obesity = 87 min vs. median normal = 52 min; z = -2.87, U = 576.50, p = 0. 004) and shorter REM sleep (median obesity = 94 min vs. median normal = 121 min; z = 5.05, U = 1477.00, p ≤ .001). No differences were observed for time in sleep stage N1 and N3, wake time after sleep onset or the total arousal index . Further, no group differences were found on the CSHQ sleep-disordered breathing sub-scale (p = 0.399). The children with obesity demonstrated significantly more mild to moderate sleep disordered breathing than children with normal weight, although this was not corroborated by parent report.

Combined Association Between ADIPOQ, PPARG, and TNF Genes Variants and Obstructive Sleep Apnea in Chinese Han Population

PURPOSE

Obstructive sleep apnea (OSA) is a common chronic polygenic disease. Multiple genetic markers associated with OSA have been identified by genome-wide association studies. Here, we aimed to construct a polygenic risk score (PRS) and examine the association with the presence of OSA in a Chinese Han Population.

PATIENTS AND METHODS

This study included 1057 individuals who were genotyped for nine susceptibility loci from three genes (ADIPOQ, PPARG, and TNF), from which each individual's PRS was calculated by summing the number of risk alleles. The associations between PRS and OSA were determined by logistic regression analyses. Model discrimination was assessed by a receiver operating characteristic (ROC) curve using bootstrapping with 1000 resamples.

RESULTS

The subjects included 874 with OSA and 183 controls. A higher PRS was associated with an increased apnea-hypopnea index (AHI). The PRS was an important risk factor for the development of OSA (OR = 1.237 per SD, P = 0.030). Subjects with higher PRS had a 2.88-fold (95% CI: 1.393-5.955, P = 0.004) and 5.402-fold (95% CI: 2.311-12.624, P<0.001) greater risk for having OSA and moderate-to-severe OSA, respectively, compared with those with lower genetic risk. More importantly, compared with determination of risk based solely on clinical factors, addition of the PRS increased discriminatory accuracy for both OSA (AUC from 0.75 to 0.78, P = 0.02) and moderate-to-severe OSA (AUC from 0.80 to 0.83, P = 0.02).

CONCLUSION

Our study suggests that the PRS is independently associated with AHI and OSA. Combining PRS with conventional risk factors could improve the discrimination of OSA.

Gender Differences in the Context of Obstructive Sleep Apnea and Metabolic Diseases

The relationship between obstructive sleep apnea (OSA) and endocrine and metabolic disease is unequivocal. OSA, which is characterized by intermittent hypoxia and sleep fragmentation, leads to and exacerbates obesity, metabolic syndrome, and type 2 diabetes (T2D) as well as endocrine disturbances, such as hypothyroidism and Cushing syndrome, among others. However, this relationship is bidirectional with endocrine and metabolic diseases being considered major risk factors for the development of OSA. For example, polycystic ovary syndrome (PCOS), one of the most common endocrine disorders in women of reproductive age, is significantly associated with OSA in adult patients. Several factors have been postulated to contribute to or be critical in the genesis of dysmetabolic states in OSA including the increase in sympathetic activation, the deregulation of the hypothalamus-pituitary axis, the generation of reactive oxygen species (ROS), insulin resistance, alteration in adipokines levels, and inflammation of the adipose tissue. However, probably the alterations in the hypothalamus-pituitary axis and the altered secretion of hormones from the peripheral endocrine glands could play a major role in the gender differences in the link between OSA-dysmetabolism. In fact, normal sleep is also different between men and women due to the physiologic differences between genders, with sex hormones such as progesterone, androgens, and estrogens, being also connected with breathing pathologies. Moreover, it is very well known that OSA is more prevalent among men than women, however the prevalence in women increases after menopause. At the same time, the step-rise in obesity and its comorbidities goes along with mounting evidence of clinically important sex and gender differences. Metabolic and cardiovascular diseases, seen as a men's illness for decades, presently are more common in women than in men and obesity has a higher association with insulin-resistance-related risk factors in women than in men. In this way, in the present manuscript, we will review the major findings on the overall mechanisms that connect OSA and dysmetabolism giving special attention to the specific regulation of this relationship in each gender. We will also detail the gender-specific effects of hormone replacement therapies on metabolic control and sleep apnea.

The impact of obstructive sleep apnea on endothelial function during weight loss in an obese pediatric population

BACKGROUND

Childhood obesity is an increasing problem with substantial comorbidities such as obstructive sleep apnea (OSA) and increased cardiovascular morbidity. Endothelial dysfunction is an underlying mechanism related to both obesity and OSA.

RESEARCH QUESTION

To investigate the effect of weight loss on endothelial function and OSA in obese children and to determine whether a change in endothelial function can be linked to an improvement in OSA.

METHODS

Obese children between 8 and 18 years of age were recruited while entering a 12-month inpatient weight loss program. Patients were followed at 3 study visits: baseline, after 10 months of weight loss, and 6 months after ending the program (18 months). Anthropometry and endothelial function (EndoPAT) were determined at all study visits. At baseline, sleep screening with a portable device (ApneaLink) was performed. This was repeated after 10 months if OSA was diagnosed at baseline.

RESULTS

At baseline, 130 children were included, of which 87 had OSA (67%). Seventy-two patients attended the follow-up visit at 10 months, and 28 patients attended the follow-up visit at 18 months. The BMI z-score decreased after 10 months (from 2.7 (1.4-3.4) to 1.7 (0.5-2.7); p < 0.001) and remained stable at 18 months. Endothelial function improved significantly after weight loss, evidenced by a shorter time to peak response (TPR) and higher reactive hyperemia index (p = 0.02 and p < 0.001), and remained improved after 18 months (p < 0.001 and p = 0.007). After 10 months of weight loss, 10 patients had residual OSA. These patients had a higher TPR at 10 months (225 (75-285)s) than those without OSA (135 (45-225)s) and patients with a normalized sleep study (105 (45-285)s; p = 0.02). Linear mixed models showed that more severe OSA was associated with a worse TPR at baseline and less improvement after weight loss.

CONCLUSION

Weight loss improves endothelial function in an obese pediatric population. However, even after weight loss, endothelial function improved less in the presence of OSA.

The Association Between Serum/Plasma Leptin Levels and Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with various adipokines. Leptin, a common adipokine, has attracted considerable attention of many researchers in recent years. So far, there has been little agreement on whether blood leptin levels differ in patients with OSAS. Thus, this meta-analysis examined the relationship between serum/plasma leptin levels and the occurrence of OSAS.

METHOD

WanFang, Embase, CNKI, Medline, SinoMed, Web of Science, and PubMed were searched for articles before March 30, 2021, with no language limitations. STATA version 11.0 and R software version 3.6.1 were used to analyze the obtained data. The weighted mean difference and correlation coefficients were used as the main effect sizes with a random-effects model and a fixed-effects model, respectively. Trial sequential analysis was conducted using dedicated software.

RESULT

Screening of 34 publications identified 45 studies that met the inclusion criteria of this meta-analysis and meta-regression. Our results suggested that plasma/serum leptin levels were remarkably higher in individuals with OSAS than in healthy individuals. Subgroup analyses were performed based on OSAS severity, ethnicity, age, body mass index, assay type, and sample source. The serum and plasma leptin levels were increased in nearly all OSAS subgroups compared to those in the corresponding control groups. Meta-regression analysis indicated that age, BMI, severity, assay approaches, study design, PSG type and ethnicity did not have independent effect on leptin levels. Furthermore, a positive relationship between the serum/plasma leptin level and apnea-hypopnea index (AHI) was found in the meta-analysis. The results of the trial sequential analysis suggested that the enrolled studies surpassed the required information size, confirming that our study findings were reliable.

CONCLUSION

Our study results demonstrate that OSAS patients have higher leptin levels in serum/plasma compared to controls, and the serum/plasma leptin level is positively correlated with AHI, especially in adults.

Evaluation of Serum and Plasma Interleukin-6 Levels in Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

Obstructive sleep apnea syndrome (OSAS) is considered a low-grade chronic inflammatory disease. Interleukin-6 (IL-6) is one of the most significant inflammatory markers and an excellent proxy for the inflammatory/immune system. The present meta-analysis and meta-regression aimed at comparing plasma and serum levels of IL-6 between individuals (children and adults) with OSAS and healthy controls. Four databases, PubMed/Medline, Scopus, Cochrane Library, and Web of Science, were comprehensively searched to retrieve articles published up to December, 2019, with no further restrictions. RevMan 5.3 software was used to calculate the crude mean difference (MD) and 95% confidence interval (CI). The results of funnel plots and meta-regression were analyzed by the CMA 2.0 software. Sixty-three studies (57 with adults; six with children) were included in the present meta-analysis. For adults, 37 studies reported significantly higher serum IL-6 levels and 20 reported significantly higher plasma IL-6 levels for those with OSAS than for healthy controls [pooled MD of 2.89 pg/ml (P < 0.00001) and pooled MD of 2.89 pg/ml (P < 0.00001), respectively]. The pooled analysis of serum and plasma IL-6 levels in children with OSAS compared with controls revealed that only the MD of plasma IL-6 levels was significant (MD = 0.84 pg/ml, P = 0.004). Results of the meta-regression showed that greater age was associated with higher serum IL-6 levels. Egger's test revealed a publication bias across the studies for serum and plasma IL-6 levels (P = 0.00044 and P = 0.01445, respectively). In summary, the meta-analysis and meta-regression confirmed that, compared to healthy controls, individuals with OSAS (children and adults) had higher serum/plasma IL-6 levels.

Association of Adipocytokines With Carotid Intima Media Thickness and Arterial Stiffness in Obstructive Sleep Apnea Patients

Objective: Obstructive sleep apnea (OSA) results in increased carotid intima-media thickness (IMT) and arterial stiffness; however, the association between adipocytokines and IMT/arterial stiffness in OSA patients is unclear. Methods: We enrolled 95 normal weight and overweight, not obese, participants from May 2018 to December 2018 in this study. All subjects underwent a carotid artery ultrasound examination and polysomnography. Blood samples were used to determine serum chemerin, adiponectin, SFRP5, and apelin levels. Correlations between two quantitative variables were assessed using the Pearson or Spearman coefficient. Stepwise models of multiple linear regression analysis were performed to assess the independent relationships. Result: IMT in OSA patients was significantly higher than in the non-snorers. There were significant differences in the arterial stiffness parameters such as distensibility coefficient (DC), compliance coefficient (CC), and pulse wave velocity (PWV). SFRP5 level was lower in OSA patients than in non-snorers. Adiponectin correlated with CC, DC, and PWV among OSA patients; however, the relationship disappeared after a multivariable adjustment. Age was independently associated with all quantitative IMT and stiffness indices. AHI and minimum oxygen saturation (Mini SaO₂) were independently related to arterial stiffness. Conclusion: The quantitative IMT and carotid arterial elasticity were significantly worse among OSA patients. Age was the main independent factor correlated with quantitative IMT and arterial stiffness, and AHI and mini SaO₂ were associated factors. There were no relationships between aforementioned adipocytokines and quantitative IMT/carotid arterial stiffness.

Adiponectin and Cardiovascular Risk. From Pathophysiology to Clinic: Focus on Children and Adolescents

Adiponectin (Ad) is a cytokine produced by adipocytes that acts on specific receptors of several tissues through autocrine, paracrine, and endocrine signaling mechanisms. Ad is involved in the regulation of cell survival, cell growth, and apoptosis. Furthermore, Ad plays an important pathophysiological role in metabolic activities by acting on peripheral tissues involved in glucose and lipid metabolism such as skeletal muscle, and the liver. Adiponectin has anti-inflammatory, anti-atherogenic, and insulin-sensitizing effects. For this reason, low levels of Ad are associated with the development of cardiovascular complications of obesity in adulthood. Numerous studies have shown that, even in children and adolescents, Ad is associated with risk factors for cardiovascular diseases. In obese children, reduced levels of Ad have been reported and Ad plasma levels are inversely related with abdominal obesity. Moreover, lower Ad concentrations are associated with the development of metabolic syndrome, insulin resistance and hypertension in pediatric subjects. In addition to a higher prevalence of cardiovascular risk factors, plasma values of Ad are also inversely associated with early organ damage, such as an increase in carotid intima-media thickness. It has been suggested that low Ad levels in childhood might predict the development of atherosclerosis in adulthood, suggesting the possibility of using Ad to stratify cardiovascular risk in obese children. Some evidence suggests that lifestyle modification may increase Ad plasma levels. The aim of this review is to summarize the evidence on the relationship between Ad, obesity, metabolic alterations and hypertension in children and adolescents, and to address the possibility that Ad represents an early marker of cardiovascular risk in pediatric subjects. Furthermore, the effects of non-pharmacological treatment (weight loss and physical activity) on Ad levels are considered.

Beneficial effects of a lifestyle intervention program on C-reactive protein: impact of cardiorespiratory fitness in obese adolescents with sleep disturbances

The objectives of this study were to assess the relationship between inflammation and obstructive sleep apnea (OSA) and determine whether the lifestyle program's effects on inflammatory markers are associated with changes in anthropometric parameters, cardiorespiratory fitness, sleep duration, and OSA severity in severely obese adolescents. Participants were aged 14.6 (SD 1.2) yr, with a body mass index (BMI) of 40.2 (SD 6.5) kg/m². Sleep, anthropometric parameters, glucose metabolism, inflammatory profile, and cardiorespiratory fitness [V̇o_2peak relative to body weight (V̇o_2peakBW) and fat-free mass (V̇o_2peakFFM)] were assessed at admission and at the end of a 9-mo lifestyle intervention program (LIP). Associations between C-reactive protein (CRP) concentrations and BMI, sex, oxygen desaturation index (ODI), sleep fragmentation, total sleep time (TST), and V̇o_2peak were assessed via ANCOVA. Twenty-three subjects completed the study. OSA subjects ( n = 13) exhibited higher CRP concentrations and a trend for higher BMI than non-OSA subjects ( P = 0.09) at admission. After intervention, OSA was normalized in six subjects, and CRP significantly decreased in the OSA group and in the whole population. In both groups, leptin levels significantly decreased, whereas adiponectin concentrations increased. At admission, BMI adjusted for sex, arousal index, ODI, TST, and V̇o_2peakBW was associated with CRP levels (adjusted r² = 0.32, P < 0.05). The decrease in CRP concentrations postintervention was associated with enhanced V̇o_2peakFFM adjusted for sex, weight loss, and changed sleep parameters (adjusted r² = 0.75, P < 0.05). Despite higher amounts of CRP in OSA subjects, obesity severity outweighs the proinflammatory effects of OSA, short sleep duration, and low cardiorespiratory fitness. However, enhanced cardiorespiratory fitness is associated with the decrease of inflammation after controlling for the same parameters.

Obstructive Sleep Apnea and Inflammation: Proof of Concept Based on Two Illustrative Cytokines

Obstructive sleep apnea syndrome (OSAS) is a markedly prevalent condition across the lifespan, particularly in overweight and obese individuals, which has been associated with an independent risk for neurocognitive, behavioral, and mood problems as well as cardiovascular and metabolic morbidities, ultimately fostering increases in overall mortality rates. In adult patients, excessive daytime sleepiness (EDS) is the most frequent symptom leading to clinical referral for evaluation and treatment, but classic EDS features are less likely to be reported in children, particularly among those with normal body-mass index. The cumulative evidence collected over the last two decades supports a conceptual framework, whereby sleep-disordered breathing in general and more particularly OSAS should be viewed as low-grade chronic inflammatory diseases. Accordingly, it is assumed that a proportion of the morbid phenotypic signature in OSAS is causally explained by underlying inflammatory processes inducing end-organ dysfunction. Here, the published links between OSAS and systemic inflammation will be critically reviewed, with special focus on the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), since these constitute classical prototypes of the large spectrum of inflammatory molecules that have been explored in OSAS patients.

Leptin and Leptin Resistance in the Pathogenesis of Obstructive Sleep Apnea: A Possible Link to Oxidative Stress and Cardiovascular Complications

Obesity-related sleep breathing disorders such as obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS) cause intermittent hypoxia (IH) during sleep, a powerful trigger of oxidative stress. Obesity also leads to dramatic increases in circulating levels of leptin, a hormone produced in adipose tissue. Leptin acts in the hypothalamus to suppress food intake and increase metabolic rate. However, obese individuals are resistant to metabolic effects of leptin. Leptin also activates the sympathetic nervous system without any evidence of resistance, possibly because these effects occur peripherally without a need to penetrate the blood-brain barrier. IH is a potent stimulator of leptin expression and release from adipose tissue. Hyperleptinemia and leptin resistance may upregulate generation of reactive oxygen species, increasing oxidative stress and promoting inflammation. The current review summarizes recent data on a possible link between leptin and oxidative stress in the pathogenesis of sleep breathing disorders.

Sleep disordered breathing and autonomic function in overweight and obese children and adolescents

Obstructive sleep apnoea (OSA), common in children with obesity, is associated with cardiovascular morbidity. Autonomic dysfunction has been suggested to be a key player in the development of these complications. We investigated the relationship between obesity, OSA and sympathetic activity in children. 191 children with obesity were included and distributed into two groups: 131 controls and 60 with OSA. Beat-to-beat RR interval data were extracted from polysomnography for heart rate variability analysis. Urinary free cortisol levels were determined. Urinary free cortisol did not differ between groups and was not associated with OSA, independent of the level of obesity. Differences in heart rate variability measures were found: mean RR interval decreased with OSA, while low/high-frequency band ratio and mean heart rate increased with OSA. Heart rate variability measures correlated with OSA, independent of obesity parameters and age: oxygen desaturation index correlated with mean heart rate (r=0.19, p=0.009) and mean RR interval (r= -0.18, p=0.02), while high-frequency bands and low/high-frequency band ratio correlated with arterial oxygen saturation measured by pulse oximetry (SpO2 ) (r= -0.20, p=0.008 and r= -0.16, p=0.04) and SpO2 nadir (r=0.23, p=0.003 and r= -0.19, p=0.02). These results suggest that sympathetic heart activity is increased in children with obesity and OSA. Measures of hypoxia were related to increased sympathetic tone, suggesting that intermittent hypoxia is involved in autonomic dysfunction.