The association between obstructive sleep apnea and dietary choices among obese individuals during middle to late childhood

Association of modifiable risk factors with obstructive sleep apnea: a Mendelian randomization study

BACKGROUND

The risk factors involved in obstructive sleep apnea (OSA) have not been clearly identified yet. We attempted to systematically investigate genetically predicted modifiable risk factors and lifestyle behaviors associated with OSA.

METHODS

The association between 34 risk factors and OSA was evaluated using the two-sample Mendelian randomization (MR). Genetic variants for risk factors were acquired from European-descent genome-wide studies. Data sources for OSA were extracted from FinnGen study with 16,761 cases and 201,194 controls. The primary analysis chosen was the inverse-variance weighted method.

RESULTS

MR analyses provide evidence of genetically predicted poor overall health rating (odds ratio (OR), 2.82; 95% confidence interval (CI), 1.95-4.08), nap during day (OR, 2.01; 95% CI, 1.37-2.93), high body mass index (BMI) (OR, 1.14; 95% CI, 1.09-1.19), increased body fat mass (OR, 1.83; 95% CI, 1.83-2.05), elevated body water mass (OR, 1.50; 95% CI, 1.31-1.70) and hypertension (OR, 1.81; 95% CI, 1.34-2.45) were associated with higher OSA risk, while high education level (OR, 0.55; 95% CI, 0.40-0.75) correlated with reduced OSA risk. Suggestive evidence was obtained for smoking and waist-to-hip ratio (WHR) with higher OSA odds, and vigorous physical activity, and HDL cholesterol with lower OSA odds. After adjusting for BMI using multivariable MR analysis, the effects of smoking, WHR, vigorous physical activity, and HDL-cholesterol were fully attenuated.

CONCLUSIONS

This MR study indicates that overall health rating, nap during day, BMI, body fat mass, body water mass, hypertension, and education are causally associated with the risk of OSA, which means that these modifiable risk factors are key targets for OSA prevention.

Overall diet quality and proinflammatory diet in relation to risk of obstructive sleep apnea in 3 prospective US cohorts

BACKGROUND

Inflammation-related mechanisms may be important in the development of obstructive sleep apnea (OSA), and diet plays a crucial role in modulating inflammation. Current epidemiologic evidence for the associations between dietary patterns and OSA risk is limited to cross-sectional studies.

OBJECTIVES

We investigated prospectively the associations of overall diet quality and proinflammatory diet with OSA risk.

METHODS

We followed 145,801 participants in the Nurses' Health Study (NHS) (2002-2012), NHS II (1995-2013), and Health Professionals Follow-up Study (1996-2012). Alternative Healthy Eating Index 2010 (AHEI) and Empirical Dietary Inflammatory Pattern (EDIP) scores were calculated based on validated FFQs administered every 4 y. Cox models were used to estimate HRs and 95% CIs.

RESULTS

We documented 8856 incident OSA cases during follow-up. In pooled analyses adjusted for potential confounders, higher diet quality (higher AHEI scores) was associated with lower OSA risk (HR comparing the highest with the lowest quintile of AHEI: 0.76; 95% CI: 0.71, 0.82; P-trend < 0.001), and higher dietary inflammatory potential (higher EDIP scores) was associated with significantly increased risk (HR comparing the highest with the lowest quintile of EDIP: 1.94; 95% CI: 1.81, 2.08; P-trend < 0.001). Additional adjustment for metabolic factors attenuated both associations. The association with AHEI score was no longer statistically significant (comparable HR: 0.98; 95% CI: 0.91, 1.05; P-trend = 0.54), whereas the association with EDIP score remained statistically significant (comparable HR: 1.31; 95% CI: 1.22, 1.41; P-trend < 0.001).

CONCLUSIONS

A healthier diet, particularly one with anti-inflammatory potential, was associated with lower OSA risk.

Unravelling the Complexity of Irregular Shiftwork, Fatigue and Sleep Health for Commercial Drivers and the Associated Implications for Roadway Safety

Fatigue can be a significant problem for commercial motor vehicle (CMV) drivers. The lifestyle of a long-haul CMV driver may include long and irregular work hours, inconsistent sleep schedules, poor eating and exercise habits, and mental and physical stress, all contributors to fatigue. Shiftwork is associated with lacking, restricted, and poor-quality sleep and variations in circadian rhythms, all shown to negatively affect driving performance through impaired in judgment and coordination, longer reaction times, and cognitive impairment. Overweight and obesity may be as high as 90% in CMV drivers, and are associated with prevalent comorbidities, including obstructive sleep apnea, hypertension, and cardiovascular and metabolic disorders. As cognitive and motor processing declines with fatigue, driver performance decreases, and the risk of errors, near crashes, and crashes increases. Tools and assessments to determine and quantify the nature, severity, and impact of fatigue and sleep disorders across a variety of environments and populations have been developed and should be critically examined before being employed with CMV drivers. Strategies to mitigate fatigue in CMV operations include addressing the numerous personal, health, and work factors contributing to fatigue and sleepiness. Further research is needed across these areas to better understand implications for roadway safety.

Sleep duration and eating behaviours among adolescents: a scoping review

INTRODUCTION

In the past decade, investigations of the relationship between sleep duration and eating behaviours have been emerging; however, a formal synthesis of the literature focussed on adolescent populations has not yet been conducted. We conducted a scoping review of the literature examining the relationship between sleep duration and eating behaviours in adolescents. Gaps in the research and directions for future research were identified based on the findings.

METHODS

A systematic search was employed on four research databases: PubMed, PsycInfo, CINAHL and Scopus; relevant grey literature was also reviewed. Studies that reported on the relationship between sleep duration and eating behaviours among high school-aged adolescents were included in the review. Data were extracted, charted and synthesized into a narrative. Consistent with the purpose of a scoping review, the methodological quality of the studies was not appraised. Stakeholders were consulted to validate the findings and provide insight into the interpretation and identification of pressing gaps in the research that remain to be addressed.

RESULTS

In total, 61 studies published between 2006 and 2021 met the criteria for review. Existing research focussed heavily on examining sleep duration in relation to intake of food from certain food groups, beverages and processed foods, and relied on a population study design, cross-sectional analyses and self-report measures.

CONCLUSION

Future research is needed to understand the link between sleep duration and eating-related cognition, eating contexts and disordered eating behaviours in order to better understand how ensuring sufficient sleep among adolescents can be leveraged to support healthier eating practices and reduce diet-related risks.

Current and future strategies for diagnostic and management of obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a common sleep disorder with multiple comorbidities including hypertension, diabetes, and cardiovascular disorders. Detected based on an overnight sleep study is called polysomnography (PSG); OSA still remains undiagnosed in majority of the population mainly attributed to lack of awareness. To overcome the limitations posed by PSG such as patient discomfort and overnight hospitalization, newer technologies are being explored. In addition, challenges associated with current management of OSA using continuous positive airway pressure (CPAP), etc. presents several pitfalls.

AREAS COVERED

Conventional and modern detection/management techniques including PSG, CPAP, smart wearable/pillows, bio-motion sensors, etc., have both pros and cons. To fulfill the limitations in OSA diagnostics, there is an imperative need for new technology for screening of symptomatic and more importantly asymptomatic OSA patients to reduce the risk of several associated life-threatening comorbidities. In this line, molecular marker-based diagnostics have shown great promises.

EXPERT OPINION

A detailed overview is presented on the OSA management and diagnostic approaches and recent advances in the molecular screening methods. The potentials of biomarker-based detection and its limitations are also portrayed and a comparison between the standard, current modern approaches, and promising futuristic technologies for OSA diagnostics and management is set forth.ABBREVIATIONS AHI: Apnea hypopnea index; AI: artificial intelligence; CAM: Cell adhesion molecules; CPAP: Continuous Positive Airway Pressure; COVID-19: Coronavirus Disease 2019; CVD: Cardiovascular disease; ELISA: Enzyme linked immunosorbent assay; HSAT: Home sleep apnea testing; IR-UWB: Impulse radio-ultra wideband; MMA: maxillomandibular advancement; PSG: Polysomnography; OSA: Obstructive sleep apnea; SOD: Superoxide dismutase; QD: Quantum dot.

Obstructive sleep apnoea and 12-month weight loss in adults with class 3 obesity attending a multidisciplinary weight management program

BACKGROUND

Although there is a strong association between obesity and obstructive sleep apnoea (OSA), the effects of OSA and CPAP therapy on weight loss are less well known. The aim of this study in adults with class 3 obesity attending a multidisciplinary weight management program was to assess the relationship between OSA and CPAP usage, and 12-month weight change.

METHODS

A retrospective cohort study of all patients commencing an intensive multidisciplinary publicly funded weight management program in Sydney, Australia, between March 2018 and March 2019. OSA was diagnosed using laboratory overnight sleep studies. Demographic and clinical data, and use of CPAP therapy was collected at baseline and 12 months. CPAP use was confirmed if used ≥4 h on average per night on download.

RESULTS

Of the 178 patients who joined the program, 111 (62.4 %) completed 12 months in the program. At baseline, 63.1 % (n=70) of patients had OSA, of whom 54.3 % (n=38) were using CPAP. The non-OSA group had more females compared to the OSA with CPAP group and OSA without CPAP group (90.2 % vs. 57.9 % and 62.5 %, respectively; p=0.003), but there were no significant baseline differences in BMI (50.4±9.3 vs. 52.1±8.7 and 50.3±9.5 kg/m², respectively; p=0.636). There was significant weight loss across all three groups at 12 months. However, there were no statistically significant differences across groups in the percentage of body weight loss (OSA with CPAP: 6.3±5.6 %, OSA without CPAP: 6.8±6.9 %, non-OSA: 7.2±6.5 %; p=0.844), or the proportion of patients who achieved ≥5 % body weight loss (OSA with CPAP: 57.9 %, OSA without CPAP: 59.4 %, non-OSA: 65.9 %; p=0.743). In patients with T2DM, there was a significant reduction in HbA1c from baseline to 12 months (7.8±1.7 % to 7.3±1.4 %, p=0.03), with no difference between groups (p=0.997).

CONCLUSIONS

This multidisciplinary weight management program resulted in significant weight loss at 12 months, regardless of OSA diagnosis or CPAP use in adults with class 3 obesity. Larger studies are needed to further investigate the effects of severity of OSA status and CPAP use in weight management programs. Until completed, this study suggests that the focus should remain on implementing lifestyle changes and weight management regardless of OSA status.

The timing of intermittent hypoxia differentially affects macronutrient intake and energy substrate utilization in mice

Sleep apnea is a common sleep disorder characterized by periodic breathing cessation and intermittent hypoxia (IH). Although previous studies have demonstrated that IH alone can influence metabolic outcomes such as body weight, it remains unclear how the timing of IH can specifically affect these outcomes. Here, we examine how pairing 10-h periods of IH to either the animals' resting phase (e.g., IH during the day) or active phase (e.g., IH during the night) differentially affects body weight, macronutrient selection, energy expenditure, respiratory exchange rate, and glucose tolerance. We find that in contrast to mice exposed to IH during the night, mice exposed to IH during the day preferentially decrease their carbohydrate intake and switch to fat metabolism. Moreover, when the IH stimulus was removed, mice that had been exposed to day IH continued to eat a minimal amount of carbohydrates and consumed a higher percentage of kilocalorie from fat for at least 5 days. These data demonstrate that food choice and substrate utilization are secondary to the timing of IH but not IH itself. Taken together, these data have key clinical implications for individuals with sleep apnea and particularly those who are also experiencing circadian disruption such as night-shift workers.NEW & NOTEWORTHY Pairing repeated hypoxic episodes to a mouse's resting phase during the day preferentially decreases carbohydrate intake and results in a switch to metabolic fat oxidation. These data indicate that the timing of intermittent hypoxia should be considered when calculating sleep apnea's effects on metabolic outcomes.

Pediatric Obstructive Sleep Apnea is Associated With Changes in the Oral Microbiome and Urinary Metabolomics Profile: A Pilot Study

STUDY OBJECTIVES

Several cross-sectional studies have reported associations between oral diseases and obstructive sleep apnea (OSA). However, there have been no reports regarding the structure and composition of the oral microbiota with simultaneous evaluation of potential associations with perturbed metabolic profiles in pediatric OSA.

METHODS

An integrated approach, combining metagenomics based on high-throughput 16S rRNA gene sequencing, and metabolomics based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and gas chromatography coupled with time-of-flight mass spectrometry, was used to evaluate the oral microbiome and the urinary metabolome.

RESULTS

16S rRNA gene sequencing indicated that the oral microbiome composition was significantly perturbed in pediatric OSA compared with normal controls, especially with regard to Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria. Moreover, metabolomics profiling indicated that 57 metabolites, 5 of which were metabolites related to the microflora of the digestive tract, were differentially present in the urine of pediatric patients with OSA and controls. Co-inertia and correlation analyses revealed that several oral microbiome changes were correlated with urinary metabolite perturbations in pediatric OSA. However, this correlation relationship does not imply causality.

CONCLUSIONS

High-throughput sequencing revealed that the oral microbiome composition and function were significantly altered in pediatric OSA. Further studies are needed to confirm and determine the mechanisms underlying these findings.

Abnormal Growth and Feeding Behavior in Upper Airway Obstruction in Rats

Pediatric obstructive sleep apnea (OSA) is a syndrome manifesting with snoring and increased respiratory effort due to increased upper airway resistance. In addition to cause the abnormal sleep, this syndrome has been shown to elicit either growth retardation or metabolic syndrome and obesity. Treating OSA by adenotonsillectomy is usually associated with increased risk for obesity, despite near complete restoration of breathing and sleep. However, the underlying mechanism linking upper airways obstruction (AO) to persistent change in food intake, metabolism, and growth remains unclear. Rodent models have examined the impact of intermittent hypoxia on metabolism. However, an additional defining feature of OSA that is not related to intermittent hypoxia is enhanced respiratory loading leading to increased respiratory effort and abnormal sleep. The focus of this mini review is on recent evidence indicating the persistent abnormalities in endocrine regulation of feeding and growth that are not fully restored by the chronic upper AO removal in rats. Here, we highlight important aspects related to abnormal regulation of metabolism that are not related to intermittent hypoxia per se, in an animal model that mimics many of the clinical features of pediatric OSA. Our evidence from the AO model indicates that obstruction removal may not be sufficient to prevent the post-removal tendency for abnormal growth.

Changes in Energy Metabolism after Continuous Positive Airway Pressure for Obstructive Sleep Apnea

RATIONALE

Disrupted energy homeostasis in obstructive sleep apnea (OSA) may lead to weight gain. Paradoxically, treating OSA with continuous positive airway pressure (CPAP) may also promote weight gain, although the underlying mechanism remains unclear.

OBJECTIVES

To explore the underlying mechanism by which patients with OSA gain weight after CPAP.

METHODS

A comprehensive assessment of energy metabolism was performed in 63 newly diagnosed OSA study participants (51 men; 60.8 ± 10.1 yr; apnea-hypopnea index >20 h(-1)) at baseline, CPAP initiation, and at a 3-month follow-up. Measurements included polysomnography, body weight, body composition, basal metabolic rate (BMR), hormones (norepinephrine, cortisol, leptin, ghrelin, insulin-like growth factor-1), dietary intake, eating behavior, and physical activity.

MEASUREMENTS AND MAIN RESULTS

BMR significantly decreased after CPAP (1,584 kcal/d at baseline, 1,561 kcal/d at CPAP initiation, and 1,508 kcal/d at follow-up; P < 0.001), whereas physical activity and total caloric intake did not significantly change. In multivariate regression, baseline apnea-hypopnea index, Δurine norepinephrine, and CPAP adherence were significant predictors of ΔBMR. The weight gainers had higher leptin levels, lower ghrelin levels, and higher eating behavior scores than the non-weight gainers, indicating a positive energy balance and disordered eating behavior among the weight gainers. Among the parameters related to energy metabolism, increased caloric intake was a particularly significant predictor of weight gain.

CONCLUSIONS

Although a reduction in BMR after CPAP predisposes to a positive energy balance, dietary intake and eating behavior had greater impacts on weight change. These findings highlight the importance of lifestyle modifications combined with CPAP. Clinical trial registered with http://www.umin.ac.jp/english/ (UMIN000012639).

Endothelial Dysfunction in Children With Obstructive Sleep Apnea Is Associated With Elevated Lipoprotein-Associated Phospholipase A2 Plasma Activity Levels

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent condition, especially in obese children, and has been associated with increased risk for endothelial dysfunction and dislipidemia, which are precursors of atherosclerosis. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is recognized as an independent risk factor for cardiovascular risk and atheromatous plaque activity. We hypothesized that Lp-PLA2 levels would be elevated in children with OSA, particularly among obese children who also manifest evidence of endothelial dysfunction.

METHODS AND RESULTS

One hundred sixty children (mean age 7.1±2.3 years), either nonobese with (n=40) and without OSA (n=40) or obese with (n=40) and without OSA (n=40) underwent overnight polysomnographic and postocclusive reperfusion evaluation and a fasting blood draw the morning after the sleep study. In addition to lipid profile, Lp-PLA2 plasma activity was assessed using a commercial kit. Obese children and OSA children had significantly elevated plasma Lp-PLA2 activity levels compared to controls. Furthermore, when both obesity and OSA were concurrently present or when endothelial function was present, Lp-PLA2 activity was higher. Treatment of OSA by adenotonsillectomy resulted in reductions of Lp-PLA2 activity (n=37; P<0.001).

CONCLUSIONS

Lp-PLA2 plasma activity is increased in pediatric OSA and obesity, particularly when endothelial dysfunction is present, and exhibits decreases on OSA treatment. The short-term and long-term significance of these findings in relation to cardiovascular risk remain undefined.

Effects of continuous positive airway pressure on energy intake in obstructive sleep apnea: A pilot sham-controlled study

Obesity is among the leading risk factors for obstructive sleep apnea (OSA). A reciprocal relationship between obesity and OSA has been proposed, which may be due to excessive food intake. We conducted a pilot study to test the effects of continuous positive airway pressure (CPAP) on energy intake (EI) in OSA patients using a sham-controlled crossover design. In-laboratory total daily EI was assessed after 2mo of active and sham CPAP. Four men were enrolled (age±SEM: 51.8±2.1y; body mass index: 31.5±1.5kg/m²). All received active treatment first. Meals (breakfast, lunch, dinner, snack) were served in excess portions at fixed times and additional palatable snacks were freely available throughout the day. Total EI was lower after active (3744±511kcal/d) vs. sham (4030±456kcal/d) CPAP but this difference was not significant (p=0.51) due to variability in the free snack intake. When only fixed eating occasions were considered, daily EI was significantly lower in the active (3105±513kcal/d) vs. sham (3559±420kcal/d) condition (p=0.006). This small pilot and feasibility study is the first to utilize a sham-controlled design to investigate the effects of CPAP treatment on objective measures of EI. Findings suggest that CPAP may cause a reduction in fixed meal intake. In demonstrating feasibility of study methodology, our study also suggests a larger randomized sham-controlled trial be conducted to fully characterize the effects of CPAP treatment on EI and energy balance overall.

Effects of continuous positive airway pressure on energy balance regulation: a systematic review

Obesity is both a cause and a possible consequence of obstructive sleep apnoea (OSA), as OSA seems to affect parameters involved in energy balance regulation, including food intake, hormonal regulation of hunger/satiety, energy metabolism and physical activity. It is known that weight loss improves OSA, yet it remains unclear why continuous positive airway pressure (CPAP) often results in weight gain.The goal of this systematic review is to explore if and how CPAP affects the behaviour and/or metabolism involved in regulating energy balance.CPAP appears to correct for a hormonal profile characterised by abnormally high leptin and ghrelin levels in OSA, by reducing the circulating levels of each. This is expected to reduce excess food intake. However, reliable measures of food intake are lacking, and not yet sufficient to make conclusions. Although studies are limited and inconsistent, CPAP may alter energy metabolism, with reports of reductions in resting metabolic rate or sleeping metabolic rate. CPAP appears to not have an appreciable effect on altering physical activity levels. More work is needed to characterise how CPAP affects energy balance regulation.It is clear that promoting CPAP in conjunction with other weight loss approaches should be used to encourage optimal outcomes in OSA patients.

Biological plausibility linking sleep apnoea and metabolic dysfunction

Obstructive sleep apnoea (OSA) is a very common disorder that affects 10-25% of the general population. In the past two decades, OSA has emerged as a cardiometabolic risk factor in both paediatric and adult populations. OSA-induced metabolic perturbations include dyslipidaemia, atherogenesis, liver dysfunction and abnormal glucose metabolism. The mainstay of treatment for OSA is adenotonsillectomy in children and continuous positive airway pressure therapy in adults. Although these therapies are effective at resolving the sleep-disordered breathing component of OSA, they do not always produce beneficial effects on metabolic function. Thus, a deeper understanding of the underlying mechanisms by which OSA influences metabolic dysfunction might yield improved therapeutic approaches and outcomes. In this Review, we summarize the evidence obtained from animal models and studies of patients with OSA of potential mechanistic pathways linking the hallmarks of OSA (intermittent hypoxia and sleep fragmentation) with metabolic dysfunction. Special emphasis is given to adipose tissue dysfunction induced by sleep apnoea, which bears a striking resemblance to adipose dysfunction resulting from obesity. In addition, important gaps in current knowledge and promising lines of future investigation are identified.

Effects of CPAP on energy expenditure in obese obstructive sleep apnoea patients: A pilot study

We conducted a placebo-controlled crossover pilot study investigating the effects of 2 mo of active and sham continuous positive airway pressure (CPAP) on energy expenditure (EE) via whole-room indirect calorimetry in three obese obstructive sleep apnoea (OSA) patients. Total 24-h (active: 2970 ± 254 kcal/d, sham: 2705 ± 217 kcal/d; p = 0.015) and mean sleeping (active: 1.60 ± 0.20 kcal/min; sham: 1.47 ± 0.17 kcal/min; p = 0.038) EE were significantly increased after active vs. sham CPAP. Findings suggest that CPAP may correct a hypoxia-related adaptive decrease in thermogenesis.

Epidemiological aspects of obstructive sleep apnea

Obstructive sleep apnea (OSA) is probably the most common respiratory disorder, with recent data from the United States and Europe suggesting that between 14% and 49% of middle-aged men have clinically significant OSA. The intimate relationship between OSA and obesity means that its prevalence will only increase as the global obesity epidemic evolves. At an individual level, OSA leads to a significant decrease in quality of life (QOL) and functional capacity, alongside a markedly increased risk of cardiovascular disease and death. Emerging data also suggest that the presence and severity of OSA and associated nocturnal hypoxemia are associated with an increased risk of diabetes and cancer. At a societal level, OSA not only leads to reduced economic productivity, but also constitutes a major treatable risk factor for hypertension, coronary artery disease (CAD) and stroke. This article addresses OSA from an epidemiological perspective, from prevalence studies to economic aspects to co-morbidity.

Sleep disturbances, body fat distribution, food intake and/or energy expenditure: pathophysiological aspects

Data from cross-sectional and longitudinal studies have illustrated a relationship between short sleep duration (SSD) and weight gain. Individuals with SSD are heavier and gain more weight over time than normal-duration sleepers. This sleep-obesity relationship may have consequences for obesity treatments, as it appears that short sleepers have reduced ability to lose weight. Laboratory-based clinical studies found that experimental sleep restriction affects energy expenditure and intake, possibly providing a mechanistic explanation for the weight gain observed in chronic short sleepers. Specifically, compared to normal sleep duration, sleep restriction increases food intake beyond the energetic costs of increased time spent awake. Reasons for this increased energy intake after sleep restriction are unclear but may include disrupted appetite-regulating hormones, altered brain mechanisms involved in the hedonic aspects of appetite, and/or changes in sleep quality and architecture. Obstructive sleep apnea (OSA) is a disorder at the intersection of sleep and obesity, and the characteristics of the disorder illustrate many of the effects of sleep disturbances on body weight and vice versa. Specifically, while obesity is among the main risk factors for OSA, the disorder itself and its associated disturbances in sleep quality and architecture seem to alter energy balance parameters and may induce further weight gain. Several intervention trials have shown that weight loss is associated with reduced OSA severity. Thus, weight loss may improve sleep, and these improvements may promote further weight loss. Future studies should establish whether increasing sleep duration/improving sleep quality can induce weight loss.

Epidemiological aspects of obstructive sleep apnea

Obstructive sleep apnea (OSA) is probably the most common respiratory disorder, with recent data from the United States and Europe suggesting that between 14% and 49% of middle-aged men have clinically significant OSA. The intimate relationship between OSA and obesity means that its prevalence will only increase as the global obesity epidemic evolves. At an individual level, OSA leads to a significant decrease in quality of life (QOL) and functional capacity, alongside a markedly increased risk of cardiovascular disease and death. Emerging data also suggest that the presence and severity of OSA and associated nocturnal hypoxemia are associated with an increased risk of diabetes and cancer. At a societal level, OSA not only leads to reduced economic productivity, but also constitutes a major treatable risk factor for hypertension, coronary artery disease (CAD) and stroke. This article addresses OSA from an epidemiological perspective, from prevalence studies to economic aspects to co-morbidity.

Obstructive sleep apnea and obesity are associated with reduced GPR 120 plasma levels in children

BACKGROUND

Obstructive sleep apnea (OSA) is a common health problem, particularly in obese children, in whom a vicious cycle of obesity and OSA interdependencies promotes increased food intake. G protein-coupled receptor 120 (GPR 120) is a long-chain free fatty acid (FFA) receptor that plays an important role in energy homeostasis, and protects against insulin resistance and systemic inflammation. We hypothesized that GPR 120 levels would be reduced in children with OSA, particularly among obese children.

STUDY DESIGN

Cross-sectional prospectively recruited cohort.

SETTING

Academic pediatric sleep program.

METHODS

Two hundred twenty-six children (mean age: 7.0 ± 2.1 y) underwent overnight polysomnographic evaluation and a fasting blood draw the morning after the sleep study. In addition to lipid profile, homeostasis model assessment of insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (hsCRP) assays, monocyte GPR 120 expression, and plasma GPR 120 levels were assessed using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay kits.

RESULTS

Obese children and those with OSA had significantly lower GPR 120 monocyte expression and plasma GPR 120 levels. Furthermore, when both obesity and OSA were present, GPR 120 levels were lowest. Linear associations emerged between GPR 120 plasma levels and body mass index (BMI) z score, as well as with apnea-hypopnea index (AHI), saturation of peripheral oxygen (SpO2) nadir, and respiratory arousal index (RAI), with RAI remaining statistically significant when controlling for age, ethnicity, sex, and BMI z score (P < 0.001). Similarly, HOMA-IR was significantly associated with GPR 120 levels, but neither low density lipoprotein nor high density lipoprotein cholesterol or hsCRP levels exhibited significant correlations.

CONCLUSIONS

G protein-coupled receptor 120 (GPR 120) levels are reduced in pediatric OSA and obesity (particularly when both are present) and may play a role in modulating the degree of insulin resistance. The short- and long-term significance of reduced GPR 120 relative to food intake and glycemic deregulation remains undefined.

The relationship between metformin therapy and sleep quantity and quality in patients with Type 2 diabetes referred for potential sleep disorders

AIMS

Given that sleep disorders are known to be related to insulin resistance, and metformin has favourable effects on insulin resistance and on ventilatory drive, we sought to determine whether metformin therapy was related to sleep variables in a group of patients with Type 2 diabetes.

METHODS

We performed a retrospective, observational study of our centre's database for patients referred for potential sleep disorders and then compared metformin-treated patients with those not treated with the drug. All study patients had undergone the same standard polysomnographic procedure. A multivariate analysis was performed to establish whether or not there was an independent relationship between metformin use and sleep variables (after adjusting for age, gender, BMI, neck circumference, cumulated risk factors and insulin use).

RESULTS

We studied 387 patients (mean ± sd age: 58.4 ± 10.8 years), of whom 314 had been treated with metformin. Total sleep time and sleep efficiency were higher in metformin-treated patients than in patients not treated with metformin [total sleep time: 6 h 39 min vs. 6 h 3 min, respectively (P = 0.002); sleep efficiency: 77.9 ± 12.3 vs. 71.5 ± 17.2%, respectively (P = 0.003)]. These differences persisted after adjustment for covariates and were observed even although metformin users had a higher BMI than did non-users (median 37.5 vs. 34.8 kg/m(2) ; P = 0.045).

CONCLUSION

We showed that metformin therapy is associated with a longer sleep duration and better sleep efficiency. Randomized clinical trials are needed to confirm metformin's favourable effect on sleep quality and quantity.

Vitamin D levels and obstructive sleep apnoea in children

AIMS/HYPOTHESIS

Obstructive sleep apnoea (OSA) is a common health problem in children. African American (AA) and obese children have higher prevalence of OSA, and are also at a higher risk of reduced vitamin D levels. We hypothesised that OSA would be associated with lower levels of plasma 25-hydroxyvitamin D (25(OH)D) and increase in the risk of metabolic dysfunction and systemic inflammation.

METHODS

In this observational cross-sectional study, 176 prospectively recruited children (mean age: 6.8±0.8 years) underwent overnight polysomnographic evaluation and a fasting blood draw the morning after the sleep study. In addition to lipid profile, homeostatic model of insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (hsCRP) assays and plasma 25(OH)D levels were assessed using ELISA kits.

RESULTS

AA children, obese children and children with OSA had significantly lower 25(OH)D levels. Linear associations emerged between 25(OH)D plasma levels and body mass index (BMI) z-score, hsCRP and HOMA-IR, as well as with apnoea-hypopnoea index (AHI) and oxygen saturation (SpO2) nadir, the latter two associations remaining statistically significant even when controlling for all other potential confounders, and independently accounting for 17.7% of the variance in 25(OH)D (p<0.01).

CONCLUSIONS

25(OH)D levels are reduced in paediatric OSA, in AA children and in obese children, particularly when all are present, and may play a role in modulating the degree of insulin resistance and systemic inflammation. The short-term and long-term significance of reduced 25(OH)D in paediatric OSA remains undefined.

Dietary intake following experimentally restricted sleep in adolescents

STUDY OBJECTIVE

To examine the relationship between sleep and dietary intake in adolescents using an experimental sleep restriction protocol.

DESIGN

Randomized crossover sleep restriction-extension paradigm.

SETTING

Sleep obtained and monitored at home, diet measured during an office visit.

PARTICIPANTS

Forty-one typically developing adolescents age 14-16 years.

INTERVENTIONS

The 3-week protocol consisting of a baseline week designed to stabilize the circadian rhythm, followed randomly by 5 consecutive nights of sleep restriction (6.5 hours in bed Monday-Friday) versus healthy sleep duration (10 hours in bed), a 2-night washout period, and a 5-night crossover period.

MEASUREMENTS

Sleep was monitored via actigraphy and teens completed validated 24-hour diet recall interviews following each experimental condition.

RESULTS

Paired-sample t-tests examined differences between conditions for consumption of key macronutrients and choices from dietary categories. Compared with the healthy sleep condition, sleep-restricted adolescents' diets were characterized by higher glycemic index and glycemic load and a trend toward more calories and carbohydrates, with no differences in fat or protein consumption. Exploratory analyses revealed the consumption of significantly more desserts and sweets during sleep restriction than healthy sleep.

CONCLUSIONS

Chronic sleep restriction during adolescence appears to cause increased consumption of foods with a high glycemic index, particularly desserts/sweets. The chronic sleep restriction common in adolescence may cause changes in dietary behaviors that increase risk of obesity and associated morbidity.

Association between sleep disorders, obesity, and exercise: a review

Decreased sleep duration and quality is associated with an increase in body weight and adiposity. Insomnia, obstructive sleep apnea, and restless legs syndrome are three of the most prevalent types of sleep disorder that lead to an increased risk for numerous chronic health conditions. Various studies have examined the impact of these sleep disorders on obesity, and are an important link in understanding the relationship between sleep disorders and chronic disease. Physical activity and exercise are important prognostic tools in obesity and chronic disease, and numerous studies have explored the relationship between obesity, sleep disorders, and exercise. As such, this review will examine the relationship between sleep disorders and obesity. In addition, how sleep disorders may impact the exercise response and how exercise may impact patient outcomes with regard to sleep disorders will also be reviewed.

The reciprocal interaction between obesity and obstructive sleep apnoea

Obesity is a significant risk factor in the pathogenesis of obstructive sleep apnoea (OSA) altering airway anatomy and collapsibility, and respiratory control. The association between obesity and OSA has led to an increasing focus on the role of weight loss as a potential treatment for OSA. To date, most discussion of obesity and OSA assumes a one-way cause and effect relationship, with obesity contributing to the pathogenesis of OSA. However, OSA itself may contribute to the development of obesity. OSA has a potential role in the development and reinforcement of obesity via changes to energy expenditure during sleep and wake periods, dietary habits, the neurohormonal mechanisms that control satiety and hunger, and sleep duration arising from fragmented sleep. Thus, there is emerging evidence that OSA itself feeds back into a complex mechanism that leads either to the development or reinforcement of the obese state. Whilst current evidence does not confirm that treatment of OSA directly influences weight loss, it does suggest that the potential role OSA plays in obesity and weight loss deserves further research.