The impact of break duration, time of break onset, and prior shift duration on the amount of sleep between shifts in heavy vehicle drivers.

This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h; p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs' sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs.

The impact of alcohol consumption on commercial eye blink drowsiness detection technology.

INTRODUCTION: Driver drowsiness detection technology that assesses eye blinks is increasingly being used as a safety intervention in the transport industry. It is unclear how alcohol consumption to common legal driving limits impacts upon this technology. The aim of the study was to assess the impact of a blood alcohol content (BAC) of 0.05% and of 0.08% on drowsiness detection technology during simulated driving. METHODS: Participants completed a 60-min driving simulation and sleepiness questionnaire under three conditions: 1-0.00% BAC, 2-0.05% BAC and 3-0.08% BAC. During the driving simulation task participants wore a commercial eye blink drowsiness detection technology (Optalert) with the drowsiness alarms silenced. RESULTS: Twelve participants (3 female) completed all alcohol conditions. Relative to baseline, all eye blink parameters were affected at 0.08% BAC (all p < 0.05), whereas 0.05% BAC only affected the composite eye blink drowsiness measure (the Johns Drowsiness Scale). CONCLUSIONS: Alcohol consumption to 0.08% BAC impaired eye blink measures to a level that would be considered a moderate drowsiness risk. Therefore, employers should be aware that drowsiness alerts from these technologies may increase after alcohol consumption.

Maternal sleep behaviours preceding fetal heart rate events on cardiotocography.

In Australia, a significant proportion of stillbirths remain unexplained. Recent research has highlighted nocturnal maternal behaviours as potentially modifiable contributors. This study determined whether sleep-related behaviours including sleep position and sleep-disordered breathing adversely affect fetuses overnight, in both uncomplicated pregnancies and those at increased risk due to hypertensive disorders or fetal growth restriction (FGR). All participants underwent polysomnography with time-synchronized fetal heart rate (FHR) monitoring (cardiotocography - CTG) in late pregnancy. CTGs were analysed for abnormal FHR events, including decelerations and reduced variability, by two blinded observers and exported into the sleep study to temporally align FHR events with sleep behaviours. For each FHR event, 10 control epochs with normal FHR were randomly selected for the same participant. Conditional logistic regression assessed the relationships between FHR events and sleep behaviours. From 116 participants, 52 had a total of 129 FHR events overnight; namely prolonged decelerations and prolonged periods of reduced variability. Significantly more FHR events were observed in women with FGR and/or a hypertensive disorder compared with uncomplicated pregnancies (P = 0.006). FHR events were twice as likely to be preceded by a change in body position within the previous 5 min, compared with control epochs (P = 0.007), particularly in hypertensive pregnancies both with and without FGR. Overall, FHR events were not temporally related to supine body position, respiratory events or snoring. Our results indicate that most fetuses tolerate sleep-related stressors, but further research is needed to identify the interplay of maternal and fetal conditions putting the fetus at risk overnight. KEY POINTS: Maternal sleep behaviours including supine position and sleep-disordered breathing are potential contributors to stillbirth but much of this work is based on self-reported data. Using time-synchronized polysomnography and cardiotocography, we found that nocturnal fetal heart rate decelerations were more likely to be preceded by a change in body position compared with epochs containing normal fetal heart rate, particularly in hypertensive pregnancies with or without fetal growth restriction. There was no temporal relationship between maternal sleeping position, snoring or apnoeic events and an abnormal fetal heart rate overnight. We conclude that most fetuses can tolerate sleep-related stressors with no evidence of fetal heart rate changes indicating compromised wellbeing. Further work needs to identify how sleep behaviours contribute to stillbirth risk and how these intersect with underlying maternal and fetal conditions.

Fetal heart rate events during sleep, and the impact of sleep disordered breathing, in pregnancies complicated by preterm fetal growth restriction: An exploratory observational case-control study.

OBJECTIVES: To evaluate fetal heart rate (FHR) patterns during sleep in pregnancies complicated by preterm fetal growth restriction (FGR). To determine whether co-existing sleep-disordered breathing (SDB) impacts on acute FHR events or perinatal outcome. DESIGN: Observational case control study. SETTING AND POPULATION: Women with preterm FGR and gestation-matched well grown controls (estimated fetal weight above the 10th percentile with normal Doppler studies); tertiary maternity hospital, Australia. METHODS: A polysomnogram, a test used to measure sleep patterns and diagnose sleep disorders, and concurrent cardiotocography (CTG), were analysed for respiratory events and FHR changes. MAIN OUTCOME MEASURES: Frequency of FHR events overnight in FGR cases versus controls and in those with or without SDB. RESULTS: Twenty-nine patients with preterm FGR and 29 controls (median estimated fetal weight 1st versus 60th percentile, P < 0.001) underwent polysomnography with concurrent CTG at a mean gestation of 30.2 weeks. The median number of FHR events per night was higher among FGR cases than among controls (3.0 events, interquartile range [IQR] 1.0-4.0, versus 1.0 [IQR 0-1.0]; P < 0.001). Women with pregnancies complicated by preterm FGR were more likely than controls to be nulliparous, receive antihypertensive medications, be supine at sleep onset, and to sleep supine (32.9% of total sleep time versus 18.3%, P = 0.03). SDB was common in both FGR and control pregnancies (48% versus 38%, respectively, P = 0.55) but was generally mild and not associated with an increase in overnight FHR events or adverse perinatal outcome. CONCLUSIONS: Acute FHR events overnight are more common in pregnancies complicated by preterm FGR than in pregnancies with normal fetal growth. Mild SDB was common in late pregnancy and well tolerated, even by fetuses with preterm FGR. TWEETABLE ABSTRACT: Mild sleep-disordered breathing seems well tolerated even by highly vulnerable fetuses.

Does continuous positive airways pressure treatment improve clinical depression in obstructive sleep apnea? A randomized wait-list controlled study.

BACKGROUND: Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder that is associated with a range of adverse daytime sequelae, including significantly higher rates of clinical depression than is seen in the general community. Improvements in depressive symptoms occur after treatment of the primary sleep disorder, suggesting that comorbid depression might be an intrinsic feature of OSA. However, there are limited data on whether treatment for OSA in patients diagnosed with clinical depression improves mood symptoms meaningfully enough to lead to the remission of the psychiatric diagnosis. METHODS: N = 121 untreated OSA patients were randomized to either continuous positive airway pressure (CPAP) treatment or waitlist control, and depressive symptoms, sleepiness and clinical depression (using a structured clinical interview) were assessed at baseline and 4 months. Linear and logistic regression analyses were conducted, controlling for baseline scores, stratification factors and antidepressant use. RESULTS: Depressive symptoms (odds ratio [OR] = -4.19; 95% confidence interval [CI] = -7.25, -1.13; p = .008) and sleepiness (OR = -4.71; 95% CI = -6.26, -3.17; p < .001) were significantly lower at 4 months in the CPAP group compared to waitlist. At 4 months, there was a significant reduction in the proportion of participants in the CPAP group meeting criteria for clinical depression, compared to the waitlist controls (OR = 0.06, 95% CI = 0.01, 0.37; p = .002). CONCLUSION: Treatment of OSA may be a novel approach for the management and treatment of clinical depression in those with comorbid sleep disordered breathing. Larger trials of individuals with clinical depression and comorbid OSA are needed.

Bilateral hypoglossal nerve stimulation for treatment of adult obstructive sleep apnoea.

BACKGROUND AND AIM: Hypoglossal nerve stimulation (HNS) decreases obstructive sleep apnoea (OSA) severity via genioglossus muscle activation and decreased upper airway collapsibility. This study assessed the safety and effectiveness at 6 months post-implantation of a novel device delivering bilateral HNS via a small implanted electrode activated by a unit worn externally, to treat OSA: the Genio™ system. METHODS: This prospective, open-label, non-randomised, single-arm treatment study was conducted at eight centres in three countries (Australia, France and the UK). Primary outcomes were incidence of device-related serious adverse events and change in the apnoea-hypopnoea index (AHI). The secondary outcome was the change in the 4% oxygen desaturation index (ODI). Additional outcomes included measures of sleepiness, quality of life, snoring and device use. This trial was registered with ClinicalTrials.gov, number NCT03048604. RESULTS: 22 out of 27 implanted participants (63% male, aged 55.9±12.0 years, body mass index (BMI) 27.4±3.0 kg·m-2) completed the protocol. At 6 months BMI was unchanged (p=0.85); AHI decreased from 23.7±12.2 to 12.9±10.1 events·h-1, a mean change of 10.8 events·h-1 (p<0.001); and ODI decreased from 19.1±11.2 to 9.8±6.9 events·h-1, a mean change of 9.3 events·h-1 (p<0.001). Daytime sleepiness (Epworth Sleepiness Scale; p=0.01) and sleep-related quality of life (Functional Outcomes of Sleep Questionnaire-10; p=0.02) both improved significantly. The number of bed partners reporting loud, very intense snoring, or leaving the bedroom due to participant snoring decreased from 96% to 35%. 91% of participants reported device use >5 days per week, and 77% reported use for >5 h per night. No device-related serious adverse events occurred during the 6-month post-implantation period. CONCLUSIONS: Bilateral HNS using the Genio™ system reduces OSA severity and improves quality of life without device-related complications. The results are comparable with previously published HNS systems despite minimal implanted components and a simple stimulation algorithm.

Exploring the associations between shift work disorder, depression, anxiety and sick leave taken amongst nurses.

This study aimed to evaluate the association between shift work disorder and mental health in hospital-based nurses. Staff completed an online survey comprising demographic questions, the Shift Work Disorder Questionnaire, Patient Health-9 and the General Anxiety Disorder-7 scale. Sick leave data were collected from archival records from the Human Resources Department. Two hundred and two nurses (95% female; age M = 35.28 years ± SD = 12) participated (42% of eligible staff). Those at high risk of shift work disorder had higher depression (M = 7.54 ± SD = 4.28 vs. M = 3.78 ± SD = 3.24; p < 0.001) and anxiety (M = 5.66 ± SD = 3.82 vs. M = 2.83 ± SD = 3.33, p < 0.001) compared to those at low risk. Linear regression models showed that being at high risk of shift work disorder was the most significant predictor of depression, explaining 18.8% of the variance in depression (R2  = 0.188, adjusted R2  = 0.184, F(1, 200) = 46.20, p < 0.001). Shift work disorder combined with the number of night shifts and alcoholic drinks on non-work days accounted for 49.7% of the variance in anxiety scores (R2  = 0.497, adjusted R2  = 0.453, F(3, 35) = 11.51, p < 0.001). Mean sick leave in those with high risk of shift work disorder was 136.17 hr (SD = 113.11) versus 103.98 hr (SD = 94.46) in others (p = 0.057). Depression and years of shift work accounted for 18.9% of the variance in sick leave taken (R2  = 0.189, adjusted R2  = 0.180, F(2, 175) = 20.36, p < 0.001). Shift work disorder is strongly associated with depression and anxiety, providing a potential target to improve mental health in shift workers. Depression, in turn, is a significant contributing factor to sick leave.

Assessing the validity of eyelid parameters to detect impairment due to benzodiazepines.

OBJECTIVE: Benzodiazepines impair driving ability and psychomotor function. Eyelid parameters accurately reflect drowsiness; however, the effects of benzodiazepines on these measures have not been extensively studied. The aim of this study was to investigate the effect of benzodiazepines on eyelid parameters and evaluate their accuracy for detecting psychomotor impairment. METHODS: Eyelid parameters were recorded during a psychomotor vigilance task (PVT) and driving simulation over 2 days, baseline, and after 20-mg oral temazepam. The utility of eyelid parameters for detecting PVT lapses was evaluated using receiver operating characteristic curves, and cut-off levels indicating impairment (≥1 and ≥2 PVT lapses per min) were identified. The accuracy of these cut-off levels for detecting driving simulator crashes was then examined. RESULTS: PVT and driving simulator performance was significantly impaired following benzodiazepine administration (p < .05). Average eyelid closure duration (inter-event duration) was a reliable indicator of PVT lapses (area under the curve [AUC] of 0.87-0.90). The cut-off value of eyelid closure duration derived from PVT AUC was able to predict driving simulator crashes with moderately high sensitivity and specificity (76.23% and 75.00%). CONCLUSIONS: Eyelid parameters were affected by benzodiazepines and accurately detected the psychomotor impairment. In particular, eyelid closure duration is a promising real-time indicator of benzodiazepine impairment.

Worth the effort? Weighing up the benefit and burden of continuous positive airway pressure therapy for the treatment of obstructive sleep apnoea in chronic tetraplegia.

STUDY DESIGN: Mixed methods OBJECTIVES: Continuous positive airway pressure (CPAP) therapy is the recommended treatment for obstructive sleep apnoea (OSA). The aim of this study was to estimate CPAP adherence in people with tetraplegia and OSA, and to explore the barriers and facilitators to CPAP use. SETTING: Hospital outpatient department in Melbourne, Australia METHODS: People with chronic tetraplegia and OSA were commenced with auto-titrating CPAP and supported for 1 month. Semi-structured interviews were conducted with participants at one month and analysed thematically. CPAP usage was measured at 1, 6 and 12 months, with "adherent" defined as achieving more than 4 h average per night. RESULTS: Sixteen participants completed the study (80% male; mean age 56 (SD = 15)). Mean nightly CPAP use at one month was 3.1 h (SD = 2.5; 38% adherent), and at 6 months and 12 months were 2.6 h (SD = 2.8; 25% adherent) and 2.1 h (SD = 3.2; 25% adherent). The perceived benefit/burden balance strongly influenced ongoing use. Burden attributed to CPAP use was common, and included mask discomfort, and physical and emotional problems. Adherent participants were motivated by the immediate daytime benefits to mood, alertness and sleepiness. There was a tendency to not recognise symptoms of OSA until after they were treated. CONCLUSION: CPAP use is challenging for people with tetraplegia, who experience substantial burden from using the device. When tolerated, the proximate benefits are substantial. People with tetraplegia need more intensive support for longer to help them overcome the burdens of CPAP and benefit from the treatment.

Sleep-disordered breathing in hypertensive disorders of pregnancy: a BMI-matched study.

Sleep-disordered breathing is more common in hypertensive disorders during pregnancy; however, most studies have not adequately accounted for the potential confounding impact of obesity. This study evaluated the frequency of sleep-disordered breathing in women with gestational hypertension and pre-eclampsia compared with body mass index- and gestation-matched normotensive pregnant women. Women diagnosed with gestational hypertension or pre-eclampsia underwent polysomnography shortly after diagnosis. Normotensive controls body mass index-matched within ±4 kg m-2 underwent polysomnography within ±4 weeks of gestational age of their matched case. The mean body mass index and gestational age at polysomnography were successfully matched for 40 women with gestational hypertension/pre-eclampsia and 40 controls. The frequency of sleep-disordered breathing in the cases was 52.5% compared with 37.5% in the control group (P = 0.18), and the respiratory disturbance index overall did not differ (P = 0.20). However, more severe sleep-disordered breathing was more than twice as common in women with gestational hypertension or pre-eclampsia (35% versus 15%, P = 0.039). While more than half of women with a hypertensive disorder of pregnancy meet the clinical criteria for sleep-disordered breathing, it is also very common in normotensive women of similar body mass index. This underscores the importance of adjusting for obesity when exploring the relationship between sleep-disordered breathing and hypertension in pregnancy. More severe degrees of sleep-disordered breathing are significantly associated with gestational hypertension and pre-eclampsia, and sleep-disordered breathing may plausibly play a role in the pathophysiology of pregnancy hypertension in these women. This suggests that more severe sleep-disordered breathing is a potential therapeutic target for reducing the prevalence or severity of hypertensive disorders in pregnancy.

Mood disorders are highly prevalent in patients investigated with a multiple sleep latency test.

PURPOSE: Excessive daytime sleepiness (EDS) is a debilitating symptom which occurs commonly in both primary sleep and mood disorders. The prevalence of mood disorders in patients with EDS, evaluated objectively with a mean sleep latency test (MSLT), has not been reported. We hypothesize that mood disorders are highly prevalent in patients being investigated for EDS. This study aims to report the prevalence of mood disorder in the MSLT population and investigate the association between mood disorder and objective and subjective scores of sleepiness. METHODS: A retrospective multicenter study of adults with a MSLT and Hospital Anxiety and Depression Score (HADS) identified over a 3-year period. The HADS is a validated questionnaire in detecting depression (HADS-D ≥ 8) and anxiety (HADS-A ≥ 11) in the sleep clinic population. Data collected included demographics, medical, and sleep study information. Mood disorder prevalence was compared to the general sleep clinic population. Correlation between measures of sleepiness and mood was performed. RESULTS: Two hundred twenty patients were included with mean age 41.1 ± 15.7 years, mean body mass index 28.6 kg/m2 of whom 30% had anxiety (HADS-A > 11) and 43% depression (HADS-D > 8). Mean results for the cohort are ESS 13.7, mean sleep latency 11.5 min, HADS-A 8.2, and HADS-D 7. There was no significant correlation between objective sleepiness, as measured by the mean sleep latency, and either HADS-A (-0.006, p = 0.93) or HADS-D score (0.002, p = 0.98). There was, however, a weak correlation between subjective sleepiness, as measured by the ESS, and the mean sleep latency (-0.25, p < 0.01), HADS-A (0.15, p = 0.03), and HADS-D (0.2, p = 0.004). There was no significant association between diagnosis of hypersomnia disorders and presence of anxiety (p = 0.71) or depression (p = 0.83). CONCLUSIONS: Mood disorders are highly prevalent in the MSLT population. There was a weak correlation found between subjective measures of sleepiness and mood disorders, but not between objective measures of sleepiness and mood disorders. Routine screening for mood disorders in patients with hypersomnolence should be considered.

Hypoglossal nerve stimulation improves obstructive sleep apnea: 12-month outcomes.

Reduced upper airway muscle activity during sleep is a key contributor to obstructive sleep apnea pathogenesis. Hypoglossal nerve stimulation activates upper airway dilator muscles, including the genioglossus, and has the potential to reduce obstructive sleep apnea severity. The objective of this study was to examine the safety, feasibility and efficacy of a novel hypoglossal nerve stimulation system (HGNS; Apnex Medical, St Paul, MN, USA) in treating obstructive sleep apnea at 12 months following implantation. Thirty-one subjects (35% female, age 52.4 ± 9.4 years) with moderate to severe obstructive sleep apnea and unable to tolerate positive airway pressure underwent surgical implantation and activation of the hypoglossal nerve stimulation system in a prospective single-arm interventional trial. Primary outcomes were changes in obstructive sleep apnea severity (apnea-hypopnea index, from in-laboratory polysomnogram) and sleep-related quality of life [Functional Outcomes of Sleep Questionnaire (FOSQ)]. Hypoglossal nerve stimulation was used on 86 ± 16% of nights for 5.4 ± 1.4 h per night. There was a significant improvement (P < 0.001) from baseline to 12 months in apnea-hypopnea index (45.4 ± 17.5 to 25.3 ± 20.6 events h(-1) ) and Functional Outcomes of Sleep Questionnaire score (14.2 ± 2.0 to 17.0 ± 2.4), as well as other polysomnogram and symptom measures. Outcomes were stable compared with 6 months following implantation. Three serious device-related adverse events occurred: an infection requiring device removal; and two stimulation lead cuff dislodgements requiring replacement. There were no significant adverse events with onset later than 6 months following implantation. Hypoglossal nerve stimulation demonstrated favourable safety, feasibility and efficacy.

Comparative Effectiveness of Supine Avoidance versus Continuous Positive Airway Pressure for Treating Supine-isolated Sleep Apnea: A Clinical Trial.

Rationale: About 20-35% of patients with obstructive sleep apnea (OSA) have supine-isolated OSA, for which supine sleep avoidance could be an effective therapy. However, traditional supine discomfort-based methods show poor tolerance and compliance to treatment and so cannot be recommended. Supine alarm devices show promise, but evidence to support favorable adherence to treatment and effectiveness at reducing excessive daytime sleepiness compared with continuous positive airway pressure (CPAP) remains limited. Objectives: To establish if alarm-based supine-avoidance treatment in patients with supine-isolated OSA is noninferior to CPAP in reducing daytime sleepiness. Methods: After baseline questionnaire administration and in-home supine-time and polysomnography assessments, patients with supine-isolated OSA and Epworth Sleepiness Scale scores ⩾8 were randomized to ⩾6 weeks of supine-avoidance or CPAP treatment, followed by crossover to the remaining treatment with repeat assessments. Noninferiority was assessed from change in Epworth Sleepiness Scale with supine avoidance compared with CPAP using a prespecified noninferiority margin of 1.5. Average nightly treatment use over all nights and treatment efficacy and effectiveness at reducing respiratory disturbances were also compared between treatments. Results: The reduction in sleepiness score with supine avoidance (mean [95% confidence interval], -1.9 [-2.8 to -1.0]) was noninferior to that with CPAP (-2.4 [-3.3 to -1.4]) (supine avoidance-CPAP difference, -0.4 [-1.3 to 0.6]), and the lower confidence limit did not cross the noninferiority margin of 1.5 (P = 0.021). Average treatment use was higher with supine avoidance compared with CPAP (mean ± standard deviation, 5.7 ± 2.4 vs. 3.9 ± 2.7 h/night; P < 0.001). Conclusions: In patients with supine-isolated OSA, vibrotactile supine alarm device therapy is noninferior to CPAP for reducing sleepiness and shows superior treatment adherence. Clinical trial registered with www.anzctr.org.au (ACTRN 12613001242718).

Can we predict sleep-disordered breathing in pregnancy? The clinical utility of symptoms.

Sleep-disordered breathing (SDB) is reported commonly during pregnancy and is associated with an increased risk of adverse maternal and fetal outcomes, but the majority of these data are based upon self-report measures not validated for pregnancy. This study examined the predictive value of screening questionnaires for SDB administered at two time-points in pregnancy, and attempted to develop an 'optimized predictive model' for detecting SDB in pregnancy. A total of 380 women were recruited from an antenatal clinic in the second trimester of pregnancy. All participants completed the Berlin Questionnaire and the Multivariable Apnea Risk Index (MAP Index) at recruitment, with a subset of 43 women repeating the questionnaires at the time of polysomnography at 37 weeks' gestation. Fifteen of 43 (35%) women were confirmed to have a respiratory disturbance index (RDI) > 5 h(-1) . Prediction of an RDI > 5 h(-1) was most accurate during the second trimester for both the Berlin Questionnaire (sensitivity 0.93, specificity 0.50, positive predictive value 0.50 and negative predictive value 0.93), and the MAP Index [area under the receiver operating characteristic (ROC) curve of 0.768]. A stepwise selection model identified snoring volume, a body mass index (BMI)≥32 kg m(-2) and tiredness upon awakening as the strongest independent predictors of SDB during pregnancy; this model had an area under the ROC curve of 0.952. We conclude that existing clinical prediction models for SDB perform inadequately as a screening tool in pregnancy. The development of a highly predictive model from our data shows promise for a quick and easy screening tool to be validated for future use in pregnancy.

Acute upper airway responses to hypoglossal nerve stimulation during sleep in obstructive sleep apnea.

RATIONALE: Hypoglossal nerve stimulation (HGNS) recruits lingual muscles, reduces pharyngeal collapsibility, and treats sleep apnea. OBJECTIVES: We hypothesized that graded increases in HGNS relieve pharyngeal obstruction progressively during sleep. METHODS: Responses were examined in 30 patients with sleep apnea who were implanted with an HGNS system. Current (milliampere) was increased stepwise during non-REM sleep. Frequency and pulse width were fixed. At each current level, stimulation was applied on alternating breaths, and responses in maximal inspiratory airflow (V(I)max) and inspiratory airflow limitation (IFL) were assessed. Pharyngeal responses to HGNS were characterized by the current levels at which V(I)max first increased and peaked (flow capture and peak flow thresholds), and by the V(I)max increase from flow capture to peak (ΔV(I)max). MEASUREMENTS AND MAIN RESULTS: HGNS produced linear increases in V(I)max from unstimulated levels at flow capture to peak flow thresholds (215 ± 21 to 509 ± 37 ml/s; mean ± SE; P < 0.001) with increasing current from 1.05 ± 0.09 to 1.46 ± 0.11 mA. V(I)max increased in all patients and IFL was abolished in 57% of patients (non-IFL subgroup). In the non-IFL compared with IFL subgroup, the flow response slope was greater (1241 ± 199 vs. 674 ± 166 ml/s/mA; P < 0.05) and the stimulation amplitude at peak flow was lower (1.23 ± 0.10 vs. 1.80 ± 0.20 mA; P < 0.05) without differences in peak flow. CONCLUSIONS: HGNS produced marked dose-related increases in airflow without arousing patients from sleep. Increases in airflow were of sufficient magnitude to eliminate IFL in most patients and IFL and non-IFL subgroups achieved normal or near-normal levels of flow, suggesting potential HGNS efficacy across a broad range of sleep apnea severity.

Subjective reports versus objective measurement of sleep latency and sleep duration in pregnancy.

This study compared self-reported sleep latency (SL) and total sleep time (TST) to objective measures on polysomnography (PSG) during pregnancy. Thirty-three women in the third trimester (T3) of pregnancy, 16 women in the first trimester (T1) of pregnancy, and 15 non-pregnant women underwent overnight PSG, and shortly after awakening reported their perceived SL and TST. Results showed that, on average, the T3 group slightly overestimated their TSTs, whereas the T1 and non-pregnant groups underestimated TSTs when compared with objective measurement. All groups overestimated SL, and perceived SL was closest to the first epoch of 10 min of uninterrupted sleep or the first epoch of slow-wave sleep, rather than the first epoch of sleep (the current definition used for diagnostic sleep studies). The wide variation in discrepancies between estimation and PSG measurement for both TST and SL shows that self-reports made by both pregnant and non-pregnant women tend to be unreliable, which has important implications both clinically and for the many studies based on self-reported sleep patterns in pregnancy.

A randomized controlled trial of a multi-dimensional intervention to improve CPAP use and self-efficacy.

OBJECTIVES: To assess the utility of a tailored intervention program to improve continuous positive airway pressure (CPAP) use and self-efficacy in individuals with obstructive sleep apnea (OSA). METHODS: 81 participants (mean age 52.1 ± 11.6 years; 35 females) with OSA were randomized to either a multi-dimensional intervention (PSY CPAP, n = 38) or treatment as usual (TAU CPAP, n = 43). The intervention included a psychoeducation session prior to CPAP initiation, a booster psychoeducation session in the first weeks of commencing CPAP, follow-up phone calls on days 1 and 7, and a review appointment on day 14. CPAP use was compared between the PSY CPAP and TAU CPAP groups at 1 week, 1 month, and 4 months. Self-efficacy scores (risk perception, outcome expectancies, and CPAP self-efficacy) were compared between groups following the initial psychoeducation session and again at 1 month and 4 months. RESULTS: CPAP use was higher in the PSY CPAP group compared to the TAU CPAP group for all time points (p = .02). Outcome expectancies improved significantly over time in PSY CPAP participants (p = .007). Change in risk perception was associated with CPAP use at 1 week (p = .02) for PSY CPAP participants. However, risk perception did not mediate the effect between group and CPAP use at 1 week. CONCLUSIONS: Interventions designed to increase self-efficacy and administered prior to CPAP initiation, repeated in the early stages of CPAP therapy, and combined with a comprehensive follow-up regime are likely to improve CPAP use. Sustained improvement in CPAP use is the ultimate goal but remains to be investigated.

Improved depressive symptoms, and emotional regulation and reactivity, in individuals with obstructive sleep apnea after short- and long-term CPAP therapy use.

Obstructive Sleep Apnoea (OSA) is associated with high rates of depression; however, if and how treatment of OSA improves depressive symptoms is unclear. To further understand this link we considered the role of emotional regulation - the ability to control and express our emotional responses - thought to be a central component of depression. This study aimed to assess changes in depressive symptoms and emotional responses in individuals with OSA after 4- and 12-months of continuous positive airway pressure (CPAP) treatment. One-hundred and twenty-one OSA participants (50 female, Mage = 51.93; mean AHI = 36.27) were recruited from a tertiary clinical sleep service prior to CPAP initiation, and randomised to either a CPAP group or a 4 month wait-list group. Participants completed the Center for Epidemiological Studies Depression Scale, the Emotional Reactivity Scale and the Difficulties in Emotion Regulation Scale at baseline, and 1-, 2-, and 4-months follow-up. The CPAP group also completed the questionnaires 12-months after CPAP initiation. CPAP use at 1 month and 12 months was 5.1h/night and 4.9h/night, respectively. Significant improvements in depressive symptoms, emotional regulation and reactivity, and subjective sleepiness were observed after 4 months in both groups, however, the within group changes were only significant for those using CPAP. After 12-months of CPAP treatment, these improvements were maintained. There was no association between CPAP treatment adherence and improvements in any outcome. CPAP treatment for 12 months may reduce symptoms of depression and improve emotional regulation in individuals with OSA.

Associations Between Amyloid Burden, Hypoxemia, Sleep Architecture, and Cognition in Obstructive Sleep Apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with an increased risk of amyloid-ß (Aß) burden, the hallmark of Alzheimer's disease, and cognitive decline. OBJECTIVE: To determine the differential impacts of hypoxemia and slow-wave sleep disruption on brain amyloid burden, and to explore the effects of hypoxemia, slow-wave sleep disruption, and amyloid burden on cognition in individuals with and without OSA. METHODS: Thirty-four individuals with confirmed OSA (mean±SD age 57.5±4.1 years; 19 males) and 12 healthy controls (58.5±4.2 years; 6 males) underwent a clinical polysomnogram, a NAV4694 positron emission tomography (PET) scan for Aß burden, assessment of APOEɛ status and cognitive assessments. Linear hierarchical regressions were conducted to determine the contributions of demographic and sleep variables on amyloid burden and cognition. RESULTS: Aß burden was associated with nocturnal hypoxemia, and impaired verbal episodic memory, autobiographical memory and set shifting. Hypoxemia was correlated with impaired autobiographical memory, and only set shifting performance remained significantly associated with Aß burden when controlling for sleep variables. CONCLUSIONS: Nocturnal hypoxemia was related to brain Aß burden in this sample of OSA participants. Aß burden and hypoxemia had differential impacts on cognition. This study reveals aspects of sleep disturbance in OSA that are most strongly associated with brain Aß burden and poor cognition, which are markers of early Alzheimer's disease. These findings add weight to the possibility that hypoxemia may be causally related to the development of dementia; however, whether it may be a therapeutic target for dementia prevention in OSA is yet to be determined.

Polysomnographic analysis of maternal sleep position and its relationship to pregnancy complications and sleep-disordered breathing.

Links between supine "going to sleep" position and stillbirth risk have led to campaigns regarding safe maternal sleep position. This study profiles the distribution of sleep positions overnight and relationships to sleep onset position during pregnancy, and the relationships between supine sleep, sleep-disordered breathing (SDB), and pregnancy outcomes. Data from three prospective cohort studies evaluating SDB in healthy and complicated pregnancies were pooled. All participants underwent one night of polysomnography in late pregnancy and birth outcome data were collected. 187 women underwent polysomnography at a median gestation of 34 weeks'. The left lateral position was preferred for falling asleep (52%) compared to supine (14%), but sleep onset position was the dominant sleep position overnight in only half (54%) of women. The median percentage of sleep time in the supine position was 24.2%; women who fell asleep supine spent more time supine overnight compared to those who began non-supine (48.0% (30.0,65.9) vs. 22.6% (5.7,32.2), p < .001). Women with growth-restricted fetuses were more likely to fall asleep supine than those with well-grown fetuses (36.6% vs. 7.5%, p < .001). Positional SDB was observed in 46% of those with an RDI ≥ 5. Sleep onset position was the dominant position overnight for half of the sample, suggesting that sleep onset position is not always a reliable indicator of body position overnight. Supine sleep was related to fetal growth restriction and birthweight at delivery, though causality cannot be inferred. It is critical that we pursue research into verifying the important relationship between supine sleep and increased stillbirth risk, and the mechanisms behind it.