Obstructive sleep apnoea (OSA) is common and burdensome, yet current diagnostic pathways remain costly and often misclassify patients. Single-night polysomnography (PSG), the diagnostic gold standard, fails to capture night-to-night variability in severity, is difficult to access and costly. Emerging technologies enable multi-night in-home evaluation, but robust comparative evidence regarding accuracy and cost-effectiveness is lacking. This study will evaluate (a) the diagnostic accuracy of three multi-night in-home devices versus conventional single night PSG; (b) the patient and signal characteristics that optimize diagnostic performance; and (c) the cost-effectiveness of these pathways for clinical implementation. We will conduct a three-arm randomized diagnostic strategy trial (n = 500) enrolling adults referred for suspected OSA over a recruitment period of several years from July 2025. All participants will undergo both conventional single-night PSG and multi-night assessment with an under-mattress sensor, oximetry ring, and forehead EEG device. Participants will be randomized to one of three diagnostic pathways, determining the order in which sleep physicians interpret test results. Sleep physicians will provide sequential diagnostic decisions at each stage, and a blinded expert panel will determine consensus diagnoses. The primary outcome is diagnostic accuracy of each pathway compared with consensus diagnosis. Secondary outcomes include cost-effectiveness, patient-reported acceptability, clinical confidence, self-reported long-term symptoms, and health and quality of life outcomes over 12 months follow-up. Findings will provide definitive evidence for whether simplified and accessible multi-night testing can improve accuracy and cost-effectiveness of OSA diagnosis in routine care.

Abstract Background Emerging evidence suggests obstructive sleep apnoea (OSA) is a risk factor for increased amyloid aggregation, a biomarker of Alzheimer’s disease, with disrupted sleep architecture hypothesised as a potential mechanism. Moreover, sleep architecture abnormalities observed in (OSA) may explain impaired cognition. However, the relationships between sleep microarchitecture, amyloid burden and cognition in OSA are unclear. Methods Thirty-four participants with OSA (age=57.7, 19 males), and 12 controls (age=57.1, 6 males) underwent diagnostic polysomnography (PSG), 11C-PiB positron emission tomography (PET) scan to quantify amyloid burden, and a cognitive assessment battery. All-night EEG recordings were processed and spectral power in slow oscillation (SO) and delta frequency ranges were calculated. Results Higher global amyloid burden was associated with lower delta power at O2 during slow wave sleep (SWS) in the OSA group (ß=-0.443, R2=0.142, p=0.048, controlled for age and non-REM AHI) and in the entire sample (ß=-.497, R2=.161, p=.019). Delta power and SO power in the OSA group was in turn associated with verbal memory (frontal regions - delta: ß=-0.811, p<0.001 and SO: ß=-0.661, p=0.008; central - delta: ß=0.537, p=0.026; occipital - delta: ß=0.586, p=0.014 and SO: ß=0.526, p =0.043). Discussion Greater amyloid burden was associated with slow wave deficits in older people with and without OSA. Worse memory performance was associated with lower slow frequency activity in central and occipital brain regions but higher activity in frontal regions. It is possible that pathological EEG slowing in some brain regions may explain the differential associations between sleep neurophysiological measures and memory.

Objective: to assess the effectiveness and acceptability of a pillow-like position modification device to reduce supine sleep during late pregnancy, and to determine the impacts on the severity of sleep-disordered breathing (SDB) and fetal wellbeing. Design: Randomised cross-over study Setting and population: Individuals in the third trimester of pregnancy receiving antenatal care at a tertiary maternity hospital in Australia. Methods: Participants used their own pillow for a control week and an intervention pillow for a week overnight, in randomized order. Sleep position and total sleep time for each night of both weeks was objectively monitored, with a sleep study and fetal heart rate monitoring performed on the last night of each week. Main Outcome Measures: Percentage of sleep time in the supine position, apnoea-hypopnoea index, fetal heart rate decelerations and birthweight. Results: Forty-one individuals were randomized with data collected on 35 participants over 469 nights. There was no difference in percentage of total sleep time in the supine position overnight between the control or intervention pillow week (13.0% [6.1, 25.5] v 16.0% [5.6, 27.2], p = .81), and no difference in the severity of SDB or fetal heart rate decelerations across weeks. However, increased supine sleep was significantly related to a higher apnea-hypopnea index (r = .37, p = .003), lower birthweight (r = -.45, p = .007) and lower customised birthweight centile (r = -.45, p = .006). The proportion of supine sleep each night of the week varied widely both within and across participants, despite awareness of side-sleeping recommendations. Conclusions: The adoption of a pillow designed to discourage supine sleep was not effective in late pregnancy, with women spending an average of one hour per night supine. Supine sleep was associated with SDB and lower birthweight. Alternative devices should be investigated, incorporating lessons learnt from this study to inform trials of supine sleep minimisation in pregnancy. Clinical Trial Registration Number – ACTRN12620000371998 (Australia New Zealand Clinical Trials Registry)

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).

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 & PLUSMN; 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.

Abstract Background Going to sleep in the supine position during pregnancy is associated with an increased risk of stillbirth, however objective sleep position data are needed to verify the mechanisms of this relationship. Sleep position measurement devices are typically worn at the neck or chest, but abdomen position is more important for assessing impact of the gravid uterus on inferior vena cava compression. This study aimed to compare sleep position measured at the neck versus the abdomen in late pregnancy. Methods Twenty women in the third-trimester of pregnancy wore the Night Shift Sleep Positioner with both the neck band and abdominal band for one night. Position classified as left, supine, right, prone and upright was recorded in 30-second epochs and compared across device locations. Results There was substantial agreement between the neck and abdomen for determination of all sleep positions with 88% concordance on an epoch-by-epoch basis (κ = .797 [SE .006], p<.001). However, agreement was only fair (κ = .407 [SE .007], p < .001) for supine versus non-supine positioning, with a trend for more supine sleep using the neck device compared to the abdomen (47.5 [16.3,80.5] vs 19.0 [6.8,83.8] minutes, median difference =7.3 [0.5,39.3], p=.12). The average absolute supine difference across device locations was 30.8 minutes [4.0,65.3]. Conclusion Position measurement at the neck and abdomen has considerable concordance on an epoch-by-epoch basis, however agreement was reduced when comparing supine position only. Site of sleep position measurement in pregnancy has implications for assessing supine positioning, intervention success and stillbirth risk.

Summary 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.

IntroductionDriver 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. MethodsParticipants 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. ResultsTwelve 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). ConclusionsAlcohol 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.

Abstract Introduction Excessive sleepiness and symptoms of depression and anxiety are highly prevalent in individuals with obstructive sleep apnoea (OSA). The aim of this study was to determine the effect of treating OSA with continuous positive airway pressure (CPAP) on mood and daytime sleepiness. Methods Seventy-eight participants (mean age 51.3±12.2 years; 41% female) with previously diagnosed OSA were randomised to either treatment as usual (TAU CPAP, n=43) or to a waitlist control group (WL, n=35). Participants in the TAU CPAP group were implemented with CPAP via an in-laboratory sleep study at the Austin Health sleep laboratory. CPAP initiation was delayed for participants in the WL group by 4 months. Sleepiness and depression, anxiety and stress symptoms, were measured at baseline and 4 months follow-up and compared between groups. CPAP use was measured in the TAU CPAP group. Results Participants in both groups reported mild symptoms of depression at baseline. Daytime sleepiness (p Discussion Daytime sleepiness was improved with 4 months of CPAP use compared to no treatment. Mood did not improve with 4 months of CPAP therapy. Developing an OSA-specific tool to measure mood symptoms may be beneficial, and future studies should carefully consider recruitment criteria to include participants with mood symptoms at baseline.

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.

Abstract Introduction Emerging literature reports an increased risk of Alzheimer’s disease in individuals with obstructive sleep apnoea (OSA). Established characteristics of Alzheimer’s disease include increased brain amyloid burden and impairment to episodic and autobiographical memory. Investigating these constructs in individuals with clinically confirmed OSA will contribute to understanding of OSA and neuronal implications. Aim The aim of the study was to explore the relationship between brain amyloid burden and autobiographical memory in cognitively-healthy individuals with OSA. Methods Thirty-four participants with OSA (mean age=57.7, SD=8.5, 19 males), and 12 controls (mean age=57.1, SD=8.1, 6 males) participated in the study. Participants underwent a 11C-PiB positron emission tomography (PET) scan to quantify amyloid burden, and an assessment of autobiographical memory. Brain amyloid burden was quantified using the standardised uptake value ratio (SUVR), and the Autobiographical Memory Test (AMT) was used to assess the ability of participants to recall specific memories from their life. Results Individuals with OSA recalled significantly fewer specific autobiographical memories (M=6.66, SD=2.91) compared to controls (M=10.25, SD=2.09, t(45)=-3.930, p Discussion Levels of brain amyloid burden did not differ significantly between groups however the results support existing literature suggesting amyloid burden is associated with autobiographical memory in individuals with OSA. Longitudinal studies investigating the trajectory of these constructs in the context of disease development should be conducted to further explore the impacts of OSA.

BACKGROUND:Obstructive sleep apnea (OSA) is associated with an increased risk of amyloid-β (Aβ) 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 Aβ 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:Aβ 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 Aβ burden when controlling for sleep variables.CONCLUSIONS:Nocturnal hypoxemia was related to brain Aβ burden in this sample of OSA participants. Aβ burden and hypoxemia had differential impacts on cognition. This study reveals aspects of sleep disturbance in OSA that are most strongly associated with brain Aβ 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.

Abstract Introduction Heavy vehicle drivers (HVDs), carrying approximately 75% of non-bulk domestic freight on Australian roads, are at risk of drowsiness due to night-time, long drives, or short sleep. Drowsiness comprises 46% of all driver-impairment-related factors in HVDs fatalities. However, the specific role of sleep loss in HVDs' drowsiness is less known. This study assessed the association of sleep loss, independent of other work metrics, with real-time drowsiness in HVDs. Methods Eight HVDs aged 49.8± 8 years, 27± 10.3 years of experience, worked for 3-28 (13± 6) shifts. A composite ocular measure of drowsiness (John's Drowsiness Score) and drivers' sleep-wake was monitored by Optalert glasses and Actiwatches, respectively. The drowsiness event (response variable) was defined as at least one event of JDS≥ 2.6 /h, and sleep loss (exposure) as the variation of sleep opportunity pre-shift from the 9-hour recommended rest break in Europe. Multivariate logistic regression assessed the odds of drowsiness events under sleep loss when adjusted for time of day, shift start time and hours of drive. Results Data comprised 1061 observations of work metrics or JDS and 694 records of sleep duration. Sleep loss ranged from 1 to 6.3 hours (3.4 ± 1.1h). Compared with a 1- 2.5-hour sleep loss, sleep loss> 4 hours doubled the likelihood of drowsiness events when controlled for other covariates (p=0.019). Discussion Sleep loss increases the odds of drowsiness events in HVDs with similar work schedule metrics. Further research should assess if Australia's 7-h minimum break provides adequate sleep under different schedule conditions.

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.

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.

Study objectives: While drowsiness contributes to 20% of heavy vehicle crashes, the impact of work schedules on heavy vehicle driver (HVD) drowsiness is unclear. This study explored the impact of work schedules on drowsiness (measured by infrared oculography) in HVDs.Method: Work and drowsiness monitoring (Optalert, Australia) of ten HVDs, aged 37-62 years collected nearly 2430 h of work and 1068 h of oculography data during four weeks of naturalistic drives. Drowsiness events were defined as a John's Drowsiness Scores >= 2.6. Nine HVDs slept for 5.82 +/- 1.37 h during five weeks of actigraphy. Association of driving schedule characteristics and drivers' continuous eye-blink parameters were observed using logistic and mixed linear regres-sion analyses.Results: Combination of time of day (10 pm-2 am), shift start time (2 pm-3 pm), hours into the shift (16-21 h), break duration (7-9 h), and sleep time (<6 h) increased the likelihood of drowsiness events when controlling for other covariates. A combination of night times (6 pm to 2 am), 18 to 21 h into the shift, shift start times (6 am to 7 am), shifts lengths (8 to15 h) and break times (<7 to 9 h) increased the hourly rate of drowsiness significantly when adjusting for other covariates.Conclusions: The combination of prolonged work hours, night-time drives, early-morning shift starts and short breaks increase drowsiness rates in HVDs. Large datasets are needed to examine the interplay between sleep time, consecutive shifts and shift order and type with this combination.

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.