Contemporary Concise Review 2022: Sleep.

COVID-19 AND SLEEP: The COVID-19 pandemic is associated with an increase in insomnia and impaired sleep quality Health care workers are particularly susceptible and improved with cognitive behavioural therapy for insomnia (CBT-I) Long COVID has significant effects on sleep OSA impacts on the severity of acute COVID-19 illness OBSTRUCTIVE SLEEP APNOEA: Large trials of clinically representative patients confirm the cardiovascular benefits of CPAP treatment in OSA CPAP may improve long-term cognitive outcomes in OSA, but further research is needed Racial disparities in OSA prevalence and mortality risk are becoming evident Periodic evaluation of OSA risk in pregnancy is important as timing may be key for intervention to prevent or treat cardiovascular risk factors INSOMNIA: Comorbid insomnia and obstructive sleep apnoea (COMISA) can frequently co-exist and the combined negative effects of both may be deleterious, particularly to cardiovascular health There is evidence for effectiveness with novel orexin receptor antagonists.

Obstructive sleep apnea during REM sleep: effects on morning and evening blood pressure.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is linked to the emergence and progression of cardiovascular complications including hypertension, stroke, arrhythmias, coronary artery disease, and heart failure. Epidemiological studies have reported that hypertension is associated with respiratory events during REM sleep. We examined the relationship between respiratory events during REM and morning and evening hypertensive blood pressure (BP) levels in a clinical sleep population. METHODS: This study included data from in-laboratory diagnostic polysomnographic studies (n = 797) from adults attending for investigation of OSA. Hypertensive BP levels were defined using BP measurements taken in the evening before and morning after polysomnography, and the use of antihypertensive medication. Regression modeling was undertaken to examine the probability of evening and morning hypertensive BP levels according to REM apnea-hypopnea index (AHI), NREM AHI, gender, age, body mass index (BMI), alcohol use, total sleep time (TST), sleep time SpO2 <90%, and smoking status. RESULTS: The probability of morning hypertensive BP levels was significantly independently associated with age (p < .001), BMI (p < .001), and REM AHI (p < .001). No significant effect was found for the male gender, NREM AHI, alcohol use, TST, sleep time SpO2 <90%, or smoking (p > .05 for all). The probability of evening hypertensive BP levels was only significantly associated with age (p < .001), male gender (p = .012), BMI (p < .001), and TST (p = .032). CONCLUSIONS: Respiratory events during REM sleep are significantly associated with morning hypertensive BP levels. Future research is needed to determine whether treatment of these events can prevent or reverse morning hypertensive BP levels.

A 12-month weight loss intervention in adults with obstructive sleep apnoea: is timing important? A step wedge randomised trial.

BACKGROUND/OBJECTIVES: Continuous positive airway pressure (CPAP) concomitant with weight loss is a recommended treatment approach for adults with moderate-severe obstructive sleep apnoea (OSA) and obesity. This requires multiple synchronous behaviour changes. The aim of this study was to examine the effectiveness of a 6-month lifestyle intervention and to determine whether the timing of starting a weight loss attempt affects weight change and trajectory after 12 months in adults newly diagnosed with moderate-severe OSA and treated at home with overnight CPAP. METHODS: Using a stepped-wedge design, participants were randomised to commence a six-month lifestyle intervention between one and six-months post-enrolment, with a 12-month overall follow-up. Adults (n = 60, 75% males, mean age 49.4 SD 10.74 years) newly diagnosed with moderate-severe OSA and above a healthy weight (mean BMI 34.1 SD 4.8) were recruited. RESULTS: After 12 months, exposure to the intervention (CPAP and lifestyle) resulted in a 3.7 (95% CI: 2.6 to 4.8, p < 0.001) kg loss of weight compared to the control condition (CPAP alone). Timing of the weight loss attempt made no difference to outcomes at 12 months. When exposed to CPAP only (control period) there was no change in body weight (Coef, [95% CI] 0.03, [-0.3 to 0.36], p = 0.86). CONCLUSIONS: The lifestyle intervention resulted in a modest reduction in body weight, while timing of commencement did not impact the degree of weight loss at 12 months. These findings support the recommendation of adjunctive weight-loss interventions within six-months of starting CPAP.

Effect of shift work on frontline doctors' mood and sleep during the COVID-19 pandemic.

Purpose: Shift work has detrimental effects on healthcare workers, which may be further compounded by frontline work during the COVID-19 pandemic. We postulated that sleep would worsen and distress would increase during COVID-ward service. Methods: Doctors (n = 18) were recruited from a tertiary centre during the second wave of the COVID-19 pandemic in Melbourne, Australia. Participants had been rostered ON to consecutive 7 day or night shifts and a week OFF over a fortnight. 9 worked on COVID wards managing positive/suspected COVID patients, and 9 were allocated to general MEDICAL wards. Participants wore wrist actigraphy, and completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and Kessler Psychological Distress Scale (K10) at baseline and the end of each week. Results: Both the COVID and MEDICAL groups spent less time in bed and had reduced total sleep time during their week ON shift compared to week OFF shift. The COVID group had worse sleep quality (PSQI Δ + 1.0, 6.8 vs 5.8, p = 0.036), daytime sleepiness (ESS Δ + 2.6, 8 vs 5.4, p = 0.014) and greater distress (K10 Δ + 1.7, 17 vs 15.3, p = 0.002) during their week ON compared to BASELINE. Conclusion: During the COVID-19 pandemic shift workers had poorer sleep during their week ON. Those working on COVID wards had greater distress during their week ON than those working on general MEDICAL wards. It is important to recognise the potential for sleep deficits and greater distress in medical workers during the pandemic.

Barriers to sleep in acute hospital settings.

OBJECTIVE: This study aimed to examine the environmental and operational factors that disrupt sleep in the acute, non-ICU hospital setting. DESIGN, SETTING AND PARTICIPANTS: This was a prospective study of adult patients admitted to an acute tertiary hospital ward (shared versus single room) and sleep laboratory (single room conducive to sleep). MAIN OUTCOME MEASURES: This study measured ambient light (lux) and sound (dB), number of operational interruptions, and questionnaires assessing sleep and mental health. RESULTS: Sixty patients were enrolled, 20 in a double bedroom located close to the nursing station ('shared ward'), 20 in a single bedroom located distant to the nursing station ('single ward') and 20 attending the sleep laboratory for overnight polysomnography ('sleep laboratory'). Sleep was disturbed in 45% of patients in the shared and single ward groups (Pittsburgh Sleep Quality Index > 5). Light levels were appropriately low across all 3 locations. Sound levels (significant effect of room F(1.38) = 6.452, p = 0.015) and operational interruptions (shared ward 5.6 ± 2.5, single ward 6.2 ± 2.9, sleep laboratory 2.7 ± 2.1 per night, p < 0.05 wards compared to sleep laboratory) were higher in the shared and single ward group compared to the sleep laboratory but not compared to each other. Noise was rated as the greatest environmental disturbance by 70% of ward patients compared to 10% in the sleep laboratory. CONCLUSION: Higher noise levels and frequent operational interruptions are potential barriers to sleep and recovery on an acute medical ward which are not ameliorated by being in a single bedroom located distant to the nursing station.

Microsleep assessment enhances interpretation of the Maintenance of Wakefulness Test.

STUDY OBJECTIVES: The Maintenance of Wakefulness Test (MWT) is used to objectively evaluate an individual's ability to remain awake; however, microsleeps are not included in the assessment. We aimed to determine if microsleep data prior to sleep onset assisted in interpretation of ability to maintain wakefulness across a range of typical patient groups. METHODS: Forty-eight patients referred for overnight polysomnography and subsequent MWT were included. Patients were divided into 3 groups (treated obstructive sleep apnea [OSA], untreated OSA, or treated idiopathic hypersomnia or narcolepsy) based on prior medical diagnosis. Demographics, clinical characteristics, polysomnography, and MWT variables, including frequency, distribution, duration, and latency of microsleeps were compared between groups. RESULTS: Microsleeps were observed in MWT trials significantly more frequently in patients with treated idiopathic hypersomnia/narcolepsy over the course of the day (0.34 ± 0.06 vs 0.07 ± 0.02 microsleeps/min; P < .001) and in patients with untreated OSA toward the end of the day (0.31 ± 0.06 vs 0.05 ± 0.02 microsleeps/min; P < .001) compared to the group with treated OSA. Microsleeps were often observed in series and earlier in patients with treated idiopathic hypersomnia/narcolepsy (10.9 ± 1.6 minutes) and those with untreated OSA (16.2 ± 2.7 minutes) compared to the group with treated OSA (24.9 ± 3.0 minutes; P < .05), and, if taken into consideration, would increase the proportion of patients demonstrating inability to maintain wakefulness by 33% and 22%, respectively. CONCLUSIONS: MWT performance varies significantly across patient groups. Microsleep analysis prior to sleep onset may be a more sensitive measure of patient daytime wakefulness than sleep latency alone and should be considered in MWT assessment. CITATION: Anniss AM, Young A, O'Driscoll DM. Microsleep assessment enhances interpretation of the Maintenance of Wakefulness Test. J Clin Sleep Med. 2021;17(8):1571-1578.

Psychoactive drug and medication use among patients referred to a tertiary sleep laboratory population.

Psychoactive drugs including alcohol, caffeine, and prescription medications are commonly consumed to alter sleep/wake states, however the prevalence and impact of these drugs among populations seeking assessment from sleep physicians are unknown. We investigated the prevalence of commonly used drugs (alcohol and caffeine), and medications in a population (N=120; 50 females and 70 males) attending a tertiary sleep clinic for diagnostic polysomnography (PSG) assessment. In addition to objective sleep assessment, participants completed questionnaires assessing sleep quality (Pittsburgh Sleep Quality Index, PSQI), daytime sleepiness (Epworth Sleepiness Scale, ESS), depression and anxiety (Hospital Anxiety and Depression Scale, HADS), alcohol use (Alcohol Use Disorders Identification Test, AUDIT), caffeine and medication use, as well as their experience of adverse events (motor vehicle accidents and near-miss crashes). Caffeine was consumed by 90% of the population and was associated with a reduction in excessive sleepiness symptomology; while high AUDIT scores were associated with increased near-miss crashes. Polypharmacy was common, with a greater number of medications associated with poorer sleep quality, and changes in sleep architecture. This study maps commonly used drugs in those attending a tertiary sleep clinic, and demonstrates associations between drug use and sleep outcomes assessed objectively and subjectively.

The physiological phenotype of obstructive sleep apnea differs between Caucasian and Chinese patients.

STUDY OBJECTIVES: The mechanisms responsible for the development of obstructive sleep apnea (phenotypic "traits") are known to differ between individuals and may differ across ethnicities. We aimed to examine whether loop gain, arousal threshold, pharyngeal collapsibility and muscle compensation differ between Chinese and Caucasian individuals with OSA. METHODS: We noninvasively determined the relative contribution of loop gain, arousal threshold, pharyngeal collapsibility, and muscle compensation from the ventilatory flow pattern recorded during a standard clinical polysomnography in a cohort of age and AHI matched Caucasian and Chinese patients with moderate-severe OSA (n = 90). RESULTS: Chinese participants had significantly more collapsible pharyngeal airways as indicated by a lower Vpassive (68.9 [51.5-75.2] vs. 74.0 [65.1-80.4] %Veupnea, U = 703, p = 0.012), but less ventilatory control instability as indicated by a lower loop gain (0.60 [0.50-0.67] vs. 0.63 [0.57-0.81], U = 762, p = 0.043) compared with Caucasian participants. Further, multiple logistic regression analyses demonstrated that the combined pharyngeal collapsibility (Vpassive) and loop gain traits help to better explain the differences between the groups beyond upper-airway collapsibility alone. No statistically significant group differences were found in muscle compensation or arousal threshold traits between groups. CONCLUSION: Individuals of Chinese descent appear to have OSA that is driven much more by the relative contribution of their anatomical predisposition and to a lesser extent nonanatomical causes compared with Caucasians. Future research should focus on determining if Chinese versus Caucasian ethnicity is an important contributing factor to clinical outcomes and therapeutic responses in OSA.

Assessing the impact of diet, exercise and the combination of the two as a treatment for OSA: A systematic review and meta-analysis.

This study aimed to provide an updated systematic review and meta-analysis of randomized controlled trials (RCT) investigating the effectiveness of lifestyle interventions on weight loss and the impact on the severity of obstructive sleep apnoea (OSA). A systematic search of five databases between 1980 and May 2018 was used to identify all RCT which employed a lifestyle intervention (i.e. diet-only, exercise-only or combination of the two) aiming to reduce the severity of OSA (assessed using the apnoea-hypopnoea index (AHI)). Random-effects meta-analyses followed by meta-regression were conducted. Ten RCT involving 702 participants (Intervention group: n = 354; Control group: n = 348) were assessed in two meta-analyses. The weighted mean difference in AHI (-8.09 events/h, 95% CI: -11.94 to -4.25) and body mass index (BMI, -2.41 kg/m2 , 95% CI: -4.09 to -0.73) both significantly favoured lifestyle interventions over control arms. Subgroup analyses demonstrated that all interventions were associated with reductions in the AHI, but only the diet-only interventions were associated with a significant reduction in BMI. No association was found between the reduction in AHI or BMI and the length of the intervention, or with baseline AHI and BMI levels. All lifestyle interventions investigated appear effective for improving OSA severity and should be an essential component of treatment for OSA. Future research should be directed towards identifying subgroups likely to reap greater treatment benefits as well as other therapeutic benefits provided by these interventions.

Sleeping Well Trial: Increasing the effectiveness of treatment with continuous positive airway pressure using a weight management program in overweight adults with obstructive sleep apnoea-A stepped wedge randomised trial protocol.

BACKGROUND: The majority of adults diagnosed with obstructive sleep apnoea (OSA) are overweight or obese. Continuous positive airway pressure (CPAP) is the most common effective therapy for OSA. However, adherence declines over time with only 50% of patients prescribed CPAP continuing to use it long term. Furthermore, a recent prospective analysis indicated that those more adherent with CPAP therapy have enhanced weight gain trajectories which in turn may negatively impact their OSA. AIM: The Sleeping Well Trial aims to establish whether the timing of starting a lifestyle weight loss intervention impacts on weight trajectory in those with moderate-severe OSA treated at home with CPAP, while testing the potential for smart phone technology to improve adherence with lifestyle interventions. METHODS: A stepped wedge design with randomisation of individuals from 1 to 6 months post-enrolment, with 5 months of additional prospective follow up after completion of the stepped wedge. This design will investigate the effect of the 6-month lifestyle intervention on people undergoing CPAP on body weight, body composition and health-related quality of life. DISCUSSION: This trial tests whether the timing of supporting the patient through a weight loss intervention is important in obtaining the maximum benefit of a lifestyle change and CPAP usage, and identify how best to support patients through this critical period. TRIAL REGISTRATION: The protocol (v1) is registered prospectively with the International Clinical Trials Registry (CTR) ACTRN12616000203459 (public access). Any amendments to protocol will be documented via the CTR. Recruitment commenced in March 2016 with data collection scheduled to finish by May 2018.

Importance of Urinary Drug Screening in the Multiple Sleep Latency Test and Maintenance of Wakefulness Test.

STUDY OBJECTIVES: Multiple sleep latency testing (MSLT) and the maintenance of wakefulness test (MWT) are gold-standard objective tests of daytime sleepiness and alertness; however, there is marked variability in their interpretation and practice. This study aimed to determine the incidence of positive drug screens and their influence on MSLT, MWT, and polysomnographic variables. METHODS: All patients attending Eastern Health Sleep Laboratory for MSLT or MWT over a 21-mo period were included in the study. Urinary drug screening for amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methadone, and opiates was performed following overnight polysomnography (PSG). Demographics and PSG variables were compared. RESULTS: Of 69 studies, MSLT (43) and MWT (26), 16% of patients had positive urinary drug screening (7 MSLT; 4 MWT). Drugs detected included amphetamines, cannabinoids, opiates, and benzodiazepines. No patient self-reported use of these medications prior to testing. No demographic, MSLT or MWT PSG data or overnight PSG data showed any statistical differences between positive and negative drug screen groups. Of seven MSLT patients testing positive for drug use, one met criteria for the diagnosis of narcolepsy and five for idiopathic hypersomnia. On MWT, three of the four drug-positive patients had a history of a motor vehicle accident and two patients were occupational drivers. CONCLUSIONS: These findings indicate drug use is present in patients attending for daytime testing of objective sleepiness and wakefulness. These data support routine urinary drug screening in all patients undergoing MSLT or MWT studies to ensure accurate interpretation in the context of illicit and prescription drug use.

Overnight Motor Skill Learning Outcomes in Obstructive Sleep Apnea: Effect of Continuous Positive Airway Pressure.

STUDY OBJECTIVE: To determine the effectiveness of continuous positive airway pressure (CPAP) therapy in alleviating known impairments in the overnight consolidation of motor skill learning in patients with obstructive sleep apnea (OSA). METHODS: Twenty-five patients with untreated moderate-severe OSA, 13 first-night CPAP users, 17 compliant CPAP users, and 14 healthy control patients were trained on a motor sequence learning task (Sequential Finger Tapping Task, SFTT) and were subsequently tested prior to and after polysomnographic recorded sleep. Measures of subjective sleepiness (Karolinska Sleepiness Scale) and sustained attention (Psychomotor Vigilance Task) were also completed before and after sleep. RESULTS: Typical analyses of overnight improvement on the SFTT show significantly greater overnight gains in motor task speed in controls (+11.6 ± 4.7%, p = 0.007) and compliant CPAP users (+8.9 ± 4.3%, p = 0.008) compared to patients with OSA (-4.86 ± 4.5%). Additional analyses suggest that these improvements in motor performance occurred prior to the sleep episode, as all groups significantly improved (15% to 22%) over a 10-min presleep rest period. Thereafter, performance in all groups significantly deteriorated over sleep (6% to 16%) with trends toward patients with OSA showing greater losses in performance compared to control patients and compliant CPAP users. No between-group differences in subjective sleepiness and sustained attention were found presleep and postsleep. CONCLUSIONS: The current data suggest impairments in overnight motor learning in patients with OSA may be a combination of deficient stabilization of memory over a sleep episode as well as increased vulnerability to time on task fatigue effects. Compliant CPAP usage possibly offsets both of these impediments to learning outcomes by improving both sleep quality and subsequent daytime function.

Weight loss from lifestyle interventions and severity of sleep apnoea: a systematic review and meta-analysis.

BACKGROUND: Excess body weight is a risk factor for obstructive sleep apnoea (OSA). The aim of the systematic review was to establish whether weight loss via lifestyle interventions such as diet and exercise are useful in the treatment of OSA. METHODS: A literature search was conducted between 1980 and February 2012. Systematic reviews and randomised controlled trials (RCTs) with participants who had OSA, were overweight or obese, and who had undergone lifestyle interventions with the aim of improving sleep apnoea were included. Meta analyses were conducted for a subset of RCTs with appropriate data. RESULTS: Two systematic reviews and eight RCTs were included. Meta-analyses were conducted for four RCTs comparing intensive lifestyle interventions to a control. The overall weighted mean differences for weight change, change in apnoea -hypopnoea index (AHI) and change in oxygen desaturation index of ≥4% were as follows: -13.76 kg (95% confidence interval (CI) -19.21, --8.32), -16.09 (95% CI -25.64, -6.54) and -14.18 (95% CI -24.23, -4.13), respectively. Although high heterogeneity within the meta analyses, all studies favoured the interventions. Long-term follow-up data from three RCTs suggest that improvements in weight and AHI are maintained for up to 60 months. CONCLUSIONS: Intensive lifestyle interventions are effective in the treatment of OSA, resulting in significant weight loss and a reduction in sleep apnoea severity. Weight loss via intensive lifestyle interventions could be encouraged as a treatment for mild to moderate OSA.

Supine position related obstructive sleep apnea in adults: pathogenesis and treatment.

The most striking feature of obstructive respiratory events is that they are at their most severe and frequent in the supine sleeping position: indeed, more than half of all obstructive sleep apnea (OSA) patients can be classified as supine related OSA. Existing evidence points to supine related OSA being attributable to unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses. The role of arousal threshold and ventilatory control instability in the supine position has however yet to be defined. Crucially, few physiological studies have examined patients in the lateral and supine positions, so there is little information to elucidate how breathing stability is affected by sleep posture. The mechanisms of supine related OSA can be overcome by the use of continuous positive airway pressure. There are conflicting data on the utility of oral appliances, while the effectiveness of weight loss and nasal expiratory resistance remains unclear. Avoidance of the supine posture is efficacious, but long term compliance data and well powered randomized controlled trials are lacking. The treatment of supine related OSA remains largely ignored in major clinical guidelines. Supine OSA is the dominant phenotype of the OSA syndrome. This review explains why the supine position so favors upper airway collapse and presents the available data on the management of patients with supine related OSA.

Nocturnal dipping is preserved in children with sleep disordered breathing regardless of its severity.

OBJECTIVE: Sleep disordered breathing (SDB) in adults has been associated with a loss of nocturnal dipping in blood pressure (BP) and heart rate, however, there have been limited studies in children. We measured BP non-invasively and continuously overnight in 105 children aged 7-12 with a range of severities of SDB and 36 non-snoring controls to examine nocturnal dipping profiles. STUDY DESIGN: Children with SDB were divided into three severity groups according to their obstructive apnea hypopnea index. Nocturnal dipping profiles across sleep stages were described both as a proportion of children exhibiting a ≥10% fall in systolic arterial pressure (SAP) and heart rate (HR) from wake to sleep and according to SAP sleep/SAP wake ratio as extreme dippers (ratio ≤ 0.8), dippers (ratio < 0.8 and ≤0.9), non-dippers (ratio < 0.9 and ≤1.0), and reverse dippers (ratio > 1.0). RESULTS: The mean fall in BP between wake and NREM 1/2, SWS, and REM sleep was not different between the groups and there were no differences between the dipping profiles of children in each group. CONCLUSIONS: SDB did not alter nocturnal dipping patterns of BP and HR compared to controls, a finding which may suggest that these young children have not been exposed to the effects of SDB long enough or that SDB severity was not great enough to affect nocturnal dipping profiles. However, further studies are required to determine if the elevated BP previously reported in this group of children will have long-term effects on the cardiovascular system.

Hypertension and obstructive sleep apnea.

Obstructive sleep apnea (OSA) is increasingly being recognized as a major health burden with strong focus on the associated cardiovascular risk. Studies from the last two decades have provided strong evidence for a causal role of OSA in the development of systemic hypertension. The acute physiological changes that occur during apnea promote nocturnal hypertension and may lead to the development of sustained daytime hypertension via the pathways of sympathetic activation, inflammation, oxidative stress, and endothelial dysfunction. This review will focus on the acute hemodynamic disturbances and associated intermittent hypoxia that characterize OSA and the potential pathophysiological mechanisms responsible for the development of hypertension in OSA. In addition the epidemiology of OSA and hypertension, as well as the role of treatment of OSA, in improving blood pressure control will be examined.

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.

Energy expenditure in obstructive sleep apnea: validation of a multiple physiological sensor for determination of sleep and wake.

PURPOSE: Obstructive sleep apnea (OSA) may be associated with increased energy expenditure (EE) during sleep. As actigraphy is inaccurate at estimating EE from body movement counts alone, we aimed to compare a multiple physiological sensor with polysomnography for determination of sleep and wake, and to test the hypothesis that OSA is associated with increased EE during sleep. METHODS: We studied 50 adults referred for routine overnight polysomnography. In addition to polysomnography, the SenseWear Pro3 Armband(TM) (Bodymedia Inc.) was placed on the upper right arm. Epoch-by-epoch agreement rate between the measures of sleep versus wake was calculated. Linear regression analyses were performed for EE against apnea-hypopnea index (AHI), 3% oxygen desaturation index (ODI), body mass index (BMI), waist-hip ratio (WHR), gender, age, and average heart rate during sleep. RESULTS: The epoch-by-epoch agreement rate was high (79.9 ± 1.6%) and the ability of the SenseWear to estimate sleep was very good (sensitivity, 88.7 ± 1.5%). However, it was less accurate in determining wake (specificity 49.9 ± 3.6%). Sleep EE was associated with AHI, 3% ODI, BMI, WHR, and male gender (p < 0.001 for all). Stepwise multiple linear regression however revealed that BMI, male gender, age, and average heart rate during sleep were independent predictors of EE (Model R (2) = 0.78). CONCLUSIONS: The SenseWear armband provides a reasonable estimation of sleep but a poor estimation of wake. Furthermore, in a selected population of OSA patients, increasing OSA severity is associated with increased EE during sleep, although primarily through an association with increased BMI. However, as our data are not adjusted for fat-free mass and the SenseWear has yet to be validated for EE in OSA patients, these data should be interpreted with caution.

Cardiac and sympathetic activation are reduced in children with Down syndrome and sleep disordered breathing.

STUDY OBJECTIVES: Sleep disordered breathing (SDB) occurs at an increased incidence in children with Down Syndrome (DS) compared to the general pediatric population. We hypothesized that, compared with typically developing (TD) children with SDB, children with DS have a reduced cardiovascular response with delayed reoxygenation after obstructive respiratory events, and reduced sympathetic drive, providing a potential explanation for their increased risk of pulmonary hypertension. DESIGN: Beat-by-beat heart rate (HR) was analyzed over the course of obstructive events (pre, early, late, post-event) and compared between groups. Also compared were the time for oxygen resaturation post-event and overnight urinary catecholamines. SETTING: Pediatric sleep laboratory. PATIENTS: Sixty-four children aged 2-17 y referred for investigation of SDB (32 DS; 32 TD) matched for age and obstructive apnea/hypopnea index. MEASUREMENT AND RESULTS: Children underwent overnight polysomnography with overnight urine collection. Compared to TD children, those with DS had significantly reduced HR changes post-event during NREM (DS: 21.4% ± 1.8%, TD: 26.6% ± 1.6%, change from late to post-event, P < 0.05). The time to resaturation post-event was significantly increased in the DS group (P < 0.05 for both NREM and REM sleep). Children with DS had significantly reduced overnight urinary noradrenaline (P < 0.01), adrenaline (P < 0.05) and dopamine levels (P < 0.01) compared with TD children. CONCLUSION: Children with DS and SDB exhibit a compromised acute cardio-respiratory response and dampened sympathetic response to SDB compared with TD children with SDB. These data may reflect autonomic dysfunction in children with DS that may place them at increased risk for cardiovascular complications such as pulmonary hypertension.