bluuebunny/crossref_metadata_2025 huggingface dataset:
O006 A double-blind randomized placebo-controlled trial on the effect of suvorexant on REM sleep and fear extinction recall
Authors: Schenker M , Zeng L , Lynskey J , Dawson A , Kay A , Rouhi S , Felmingham K , Nicholas C , O’Donoghue F , Jenkins C , Thornton T , Jordan A
Published: December 2024

Disturbed sleep is common after trauma exposure. Individuals seeking relief may consult their GP and are frequently prescribed benzodiazepines. However, these drugs are detrimental as they can impair extinction processes (i.e., the reduction of the conditioned fear response to trauma-related stimuli over time) and thus increase the risk of developing post-traumatic stress disorder (PTSD). Additionally, benzodiazepines may disrupt rapid eye movement (REM) sleep, which is crucial for consolidating emotional memories. Therefore, this study explored suvorexant as a potential alternative to increase REM sleep and improve extinction consolidation compared to temazepam and placebo. Thirty healthy adults (age M=26.23, SD=7.55) completed a two-day fear conditioning paradigm, receiving either drug (double-blinded) before in-lab overnight PSG and returning for extinction recall testing 48h later. There was no significant difference between groups in REM sleep, F(1, 28)=0.01, p=.94. However, there was a significant effect for REM sleep (p=.01) and a REM by drug interaction (p<.01) on extinction recall. Post-hoc tests revealed that in the placebo group, increased REM sleep was associated with a reduced fear response indicative of better extinction recall (p=.01), with no association found in the other conditions (p>.05). Despite unsuccessful REM sleep manipulations, results suggest that in PTSD with disrupted REM sleep, suvorexant might mimic the effect seen with placebo in healthy controls, leading to improved extinction recall. However, this needs to be replicated in a clinical PTSD sample. If confirmed, suvorexant may reduce the risk of PTSD development through improving sleep-dependent extinction processes, thus offering a viable alternative to harmful benzodiazepines.
O008 Temporal Associations between Sleep and Caffeine Consumption in Young Adults
Authors: O’Keeffe K , van den Berg M
Published: December 2024

Aims

Laboratory studies suggest that caffeine consumption has clear and consistent adverse effects on sleep, but epidemiological studies have yielded mixed findings. This study aimed to examine temporal associations between sleep and caffeine consumption in young adults.

Methods

Fifty-one New Zealand young adults (aged 18-25 years) wore an actigraph and completed a sleep diary for 7 days to capture objective and self-reported measures of sleep and self-reported caffeine intake, providing 355 observations. Mixed linear models were conducted to assess temporal associations between caffeine intake (dose and timing) and the subsequent night’s sleep. Lagged models were conducted to assess temporal associations between sleep characteristics and next-day caffeine dose. Independent variables for caffeine and sleep were included in models as within-person and between-person variances from the mean.

Results

Between participants, those who consumed more caffeine per day than the group average had shorter total night time (β=-0.12; p=0.02) and daily (β=-0.12; p=0.02) sleep durations in the subsequent sleep period(s). Conversely, between participants, those with shorter night time (β=-0.06; p=0.004) and daily (β=-0.06; p=0.01) sleep durations consumed more caffeine in total the following day. Within participants, on days with longer night time (β=0.07; p=0. 001)and daily (β=0.05; p=0.02) sleep durations than their personal average, they consumed more caffeine the next day.

Conclusion

There may be a cycle of activity in young adults whereby higher caffeine consumption leads to shorter sleep, which leads to higher caffeine consumption. Further research that accounts for prior sleep history is needed to elucidate associations with sleep characteristics.
O014 Feasibility of evaluating early markers of neurodegeneration in a sleep clinic setting
Authors: Nelson A , D’Rozario A , Hoyos C , Naismith S , Phillips C , Yee B , Grunstein R , Chapman J
Published: December 2024

Introduction

Obstructive sleep apnea (OSA) is an emerging risk factor for cognitive decline. Sleep clinics are well positioned to screen for early biomarkers. We will evaluate the feasibility of cognitive testing and neurodegenerative blood-biomarker collection in a sleep clinic.

Methods

Males and females (>40 years) referred for polysomnography on suspicion of OSA, who consent to be contacted regarding research were invited to participate. Exclusions included existing OSA or any neurological condition.

Participants underwent in-laboratory overnight polysomnography and questionnaires, with additional blood sampling and abbreviated neuropsychological testing.

Results

Over 16 months of recruitment, 968 patients >40 were referred for polysomnography. Of 73 contactable patients who met all eligibility criteria, 59 (80.8%) stated willingness to participate. The only reason for non-participation was unavailability for morning testing (n=14, 19.2%). In preliminary analysis, 57 participants (female=17, age 56.0±10.2) had completed testing.

Moderate-severe OSA (AHI>15) was diagnosed in 24 (42.1%) participants (median(IQR) 13.3 (7.6-32.3). 10 (18%) participants showed mild impairment on the Montreal Cognitive Assessment (MoCA) (score<26) (mean± SD 27.3±1.9). The test of premorbid functioning (TOPF) was high (116±8.8).

Discussion

Over 80% of patients were receptive to additional brain health screening during routine sleep assessments. There were fewer instances of mild impairment compared with recent literature (Beaudin 2021). The TOPF scores indicate high premorbid functioning that may be protective. Data collection will be continued including 12-month follow-up. Future analyses will explore quantitative sleep metrics, further cognitive domains and blood-based biomarkers of neurodegeneration which may detect early changes in this representative sleep clinic cohort.
O017 Investigating the role of amyloid burden on sleep microarchitecture and associations with cognitive functioning in individuals with OSA
Authors: Rawson G , Lam A , Cavuoto M , Barnes M , O’Donoghue F , Howard M , Robinson S , Rowe C , D’Rozario* A , Jackson* M
Published: December 2024

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.
O019 Understanding sleep-wake disturbances in dementia with Lewy bodies using parametric and non-parametric measures in wrist actigraphy
Authors: Anderson J , Chiu N , Pye J , Grunstein R , Lewis S , Matar E
Published: December 2024

Introduction

Sleep-wake disturbances are a commonly reported non-motor symptom in dementia with Lewy bodies patients (DLB). Wrist actigraphy offers a low-burden, cost-effective option to measure sleep disturbances and has demonstrated alterations in rest-activity patterns in other synucleinopathies. This study reports both parametric and non-parametric actigraphy variables in DLB and investigates their associations with cognitive, behavioural, and quality of life measures.

Methods

Eleven participants with DLB (10:1, M:F) and 7 age-matched healthy controls (5:2, M:F) completed a battery of neuropsychological, cognitive and motor assessments and were given an actigraphy device for 2 weeks. Mann-Whitney U tests were used to compare groups and Spearman’s correlation was used to assess the relationship between actigraphy and cognitive, behavioural and quality of life measures.

Results

DLB patients reported lower cognitive (p=0.002), motor function (p<0.001) and non-motor function scores (p=0.001), along with increased depression (p=0.014). There were no significant differences between groups for total sleep time or percentage of time awake. However, compared to controls, DLB patients reported higher interdaily variability (transitions between rest and activity) (p=0.015) and lower relative amplitude (the difference between the leave active 5-hour and most active 10-hour patterns in an average 24-hour period) (p=0.011). Furthermore, interdaily stability (the relationship between rest-activity rhythm and the zeitgeber) was positively correlated with depression, hallucinations, and cognitive fluctuations.

Discussion

Wrist actigraphy and its non-parametric measures may serve as a valuable tool for investigating sleep-wake disturbances in patients with DLB and help better understand the pathophysiological role of rest-activity and circadian rhythm disruption in this condition.
O023 Circadian Photoreception Influences Loss Aversion
Authors: Lander A , Burge M , Thomas B , Phillips A , McGlashan E , Cain S
Published: December 2024

Introduction

Gambling behaviour is a growing societal problem. While previous work has explored how sound encourages gambling, an unexplored element that may play a role is the impact of circadian photoreception on cognitive processes underlying this behaviour. This study investigated the influence of circadian photoreception on loss aversion in gambling by altering the blue content of light while maintaining the same visual brightness (200 lux).

Methods

Fifteen participants (5 male, M = 20.40, SD = 2.03) completed an economic decision-making task under blue-enriched and blue-depleted light on separate occasions. The task required participants to choose between a risky gamble of positive or negative value or a less risky guaranteed outcome. Hierarchical Bayesian Modelling derived individual parameter estimates for loss aversion and trial-by-trial performance was analysed using linear mixed models.

Results

Light condition significantly influenced loss aversion, with blue-enriched light associated with a.63 decrease in loss aversion (p <.01). Significant sex differences were also found, with women displaying greater loss aversion across both light conditions.

Conclusions

This study presents evidence that light that preferentially targets circadian photoreception reduces loss aversion and suggests that reducing the blue light content in gambling scenarios may be a promising target for reducing gambling behaviour.
O031 The feasibility and efficacy of combined treatment for primary school-aged children with posttraumatic stress disorder and sleep disturbance
Authors: Rose C , Nixon R , Paterson J
Published: December 2024

Introduction

One in three primary school aged children will experience trauma, such as exposure to death, injury, or violence, with up to 77% reporting sleep disturbances. Trauma-focused cognitive behavioural therapy (TF-CBT) is the primary treatment but does not specifically address sleep issues. Adequate sleep is essential for consolidating adaptive safety beliefs and engaging in fear extinction. Without addressing sleep, treatments for posttraumatic stress disorder in children may be less effective. Treating sleep first can build rapport, improve memory consolidation and emotional regulation, and enhance engagement and confidence. Research in adults shows significant trauma symptom improvement following sleep treatments.

Methods

This study assesses the feasibility and efficacy of an integrated treatment for trauma-exposed children (5-12 years; n = 25) with sleep disturbances. The open trial includes 10 one-hour sessions and a 3-month follow-up. The first four sessions focus on CBT-I for sleep, followed by six TF-CBT sessions for trauma. Feasibility and efficacy will be evaluated using Bowen’s Feasibility Study Framework.

Results

Preliminary analysis of three participants after CBT-I (mid-treatment) shows a one-hour increase in total sleep time, but no significant change in PTSD symptoms. One participant who completed therapy showed significant symptom reduction on both the CBCL and CSHQ, with scores below the clinical cut-off post-treatment.

Conclusion

Initial findings suggest that CBT-I effectively increases total sleep time, though does not have an impact on PTSD symptoms. Further data collection and analysis with a larger sample size are necessary to substantiate these findings.
O037 Deep learning model of respiratory waveform prediction for an optogenetic therapy for obstructive sleep apnoea.n
Authors: Bull C , Kulaga T , Lovell N , Bilston L
Published: December 2024

Introduction

A novel therapeutic application of optogenetic stimulation as a treatment for Obstructive Sleep Apnea (OSA) requires stimulation of the pharyngeal muscles synchronously with the onset of inspiration to maintain airway patency during sleep1. A sensor array in a removable oral appliance was developed to monitor physiological data; photoplethysmography, acceleration, temperature and audio to predict respiratory airflow. This could then deliver correctly timed stimulation pulses coinciding with inspiration onset as part of a potential therapy.

Methods

Twenty participants underwent daytime respiratory monitoring (flow, volume and mask pressure) with concurrent monitoring using the oral sensor appliance. Participants were coached to perform multiple breathing patterns; spontaneous, fast and slow breathing, apneas, coughs and snores in supine, left and right-side sleeping positions. Sensor data was used to train a Long Short-Term Memory (LSTM) deep learning model against airflow data to predict respiration waveforms.

Results

A LSTM deep learning model was trained on over 24,000 seconds of physiological data from the 20 participants to predict respiratory waveforms. The model successfully predicted 5-second respiratory waveforms from the preceding 10 seconds of physiological data with acceptable accuracy (Mean Squared Error = 0.078, Root Mean Squared Error = 0.278), enabling real-time targeted optogenetic stimulation timing.

Discussion

This study establishes a proof of concept for using an oral sensory appliance in conjunction with optogenetic therapy for OSA. Furthermore, the sensor array demonstrates promise as a potential platform for vital sign and sleep monitoring within the oral cavity.
O040 Investigating the effects of airflow signal filtering on non-invasively quantified estimates of flow limitation
Authors: Mann D , Staykov E , Sands S , Terrill P
Published: December 2024

Introduction

We previously reported a method to estimate flow limitation (FL, range 0-~1) from the airflow signal recorded within a polysomnogram. This method utilised high quality nasal pressure signals, without high-pass (HP) filtering. However, many clinical recording systems implement HP filtering on airflow signals. We hypothesised that FL estimates would be adversely affected when airflow signals have HP filtering present.

Methods

Within our existing framework for estimating FL, we manipulated the airflow signal by applying digital HP filtering (Butterworth, 4th order) at commonly used cutoff frequencies (0.005, 0.01, 0.03, 0.1Hz). At each HP filter cutoff, performance was assessed at the breath-level (pooled, all patients) and patient-level (median, sleep only) using coefficient of determination (R²) and root mean squared error (RMSE) comparing FL estimates with HP filtering against reference data without HP filtering.

Results

In N=96 individuals, R² decreased while RMSE increased as HP filter cutoff increased. For HP filter cutoffs at 0.005, 0.01, 0.03 and 0.1Hz, breath-level R² was 0.923, 0.879, 0.740, and 0.483; while RMSE was 0.062, 0.079, 0.129, and 0.219, respectively. Similarly, patient-level R² was 0.994, 0.977, 0.843, and 0.738; while RMSE was 0.015, 0.030, 0.100, and 0.170.

Discussion

Increasing HP cutoff frequency resulted in a reduction of consistency of FL estimates when compared to those made using an unfiltered airflow signal. Further work including reference to ‘gold standard’ is required, however, in line with current AASM recommendation (“Direct current (DC) or ≤0.03Hz”), this study suggests HP filter cutoff frequency for nasal pressure should be minimised, preferably avoided.
O042 Parent-reported prevalence of sleep disordered breathing in Australian children with neurodevelopmental disorders
Authors: Anderson M , Vandeleur M , Waters K , Chawla J
Published: December 2024

Introduction

Sleep problems are a common yet complex issue for children with neurodevelopmental disorders (ND), affecting up to 80% of these individuals. The aetiology is multifactorial, including physiological, anatomical, psychological, and iatrogenic factors which contribute to problematic, and often persistent, sleep issues. Few studies have evaluated the prevalence of sleep disordered breathing (SDB) in a broad population of children with ND. This study aims to evaluate the parent-reported prevalence of SDB in children with ND.

Methods

As part of a multi-site, cross-sectional survey, caregivers of community-based and hospital-referred children with ND completed the paediatric sleep questionnaire (PSQ). PSQ was scored according to validated methods, including the subscales of snoring, sleepiness, and behaviour. Data were analysed, including stratification by age, sex, and ND type.

Results

There were 294 participants, with 261 PSQ responses available for analysis (54% male, median age 8.7yrs). 41.4% of children had a genetic syndrome, 24.1% autism spectrum disorder and attention deficit hyperactivity disorder, 16.5% neurological disorders, 13.4% undiagnosed/other ND and 4.6% unspecified. 74.7% of children had parent-reported SDB (PSQ>0.33), with a mean/median PSQ score of 0.46±0.19. Snoring, sleepiness, and behavioural subscale scores were 0.27±0.34, 0.52±0.34, and 0.70±0.33 respectively.

Discussion

This study is the first to report on the prevalence of parent-reported symptoms of SDB in a large cohort of Australian children with ND. It demonstrates a high pretest probability of SDB with 75% of participants having a positive PSQ result. These findings highlight the importance of screening for SDB in children with ND to ensure early intervention.
O045 Repetitive transcranial magnetic stimulation improves sleep in children with autism spectrum disorder
Authors: Ezedinma U , Burgess S , Singh J , Jones E , Nikles J , Ladmas A , Campell G , Fjaagesund S , Swierkowski P , Metse A , Downer T , Oprescu F
Published: December 2024

Introduction

There are no controlled studies examining the impact of repetitive transcranial magnetic stimulation (α-rTMS) on sleep difficulties in children with autism spectrum disorder (ASD).

Method

Twenty children (6-12yrs old; 16 males) with ASD (level 2) and sleep difficulties were recruited and randomised into α-rTMS and waitlist control groups (1:1). The treatment group received ten sessions of α-rTMS. Sleep outcomes were assessed at baseline and immediately post-α-rTMS on the Children Sleep Habit Questionnaire (CSHQ).

Result

The total CSHQ score was significantly improved in the treatment group as compared to the waitlist control group (-12.6; 95% CI –22.3, –2.3; p= 0.015; d= -1.25). Bedtime resistance (-0.61; 95% CI –1.04, –0.19; p= 0.008; d= -1.418), sleep onset delay (-1.0; 95% CI –1.7, -0.3; p= 0.006; d=-1.4), and sleep duration (-0.6; 95% CI –0.19 to –0.9, p= 0.007, d= -1.5), all improved. The treatment group reported no adverse events.

Conclusion

Preliminary evidence suggests that α-rTMS is well-tolerated and improves sleep difficulties in children with ASD.
O049 Maintaining long-term functional optogenetic stimulation for OSA therapy in a rodent model
Authors: Knapman F , Cohen M , Rail K , Turner A , Swain R , Kulaga T , Lovell N , Lisowski L , Shklovskaya E , Burke P , Bilston L
Published: December 2024

Introduction

Obstructive sleep apnoea (OSA) patients are often sub-optimally treated due to poor tolerance and/or incomplete responses to established therapies. Our novel therapy sensitises upper airway muscles to light (optogenetics) and allows their activation during sleep. Previous work has demonstrated that an adeno-associated viral vector (AAV) driven by a muscle-specific promoter produces strong expression of light-sensitive proteins (opsins) in the tongue, and strong light-evoked muscle activation 3-weeks after administration. Here we determine whether this response persists over 12-weeks, and whether immunosuppression is required.

Methods

Rats received intralingual injections of the AAV. After 12-weeks, opsin expression in the tongue was quantified via confocal imaging. Light-evoked muscle activation was recorded in a model of sleep-associated muscle hypotonia. This was repeated in three additional groups of animals. Group 1 received rapamycin (4 mg/kg/day) and cyclosporin (5 mg/kg/day), group 2 received prednisolone (1 mg/kg/day, tapering 10%/week from week 9), and group 3 received daily vehicle intrapleural injections.

Results

Without immunosuppression, opsin expression decreased ~4-fold in the tongue between 3- and 12-weeks post-AAV administration (two-way RM ANOVA, p=0.01). Subsequently, light-evoked muscle-activation also declined (linear mixed model, time*stimulation, p<0.001). With rapamycin/cyclosporin administration, light stimulation at 12-weeks was able to increase muscle-activation ~2-fold (p<0.001). Prednisolone and vehicle administration did not facilitate light-evoked muscle-activation at 12-weeks (p>0.05; LMM, group*stimulation p<0.001).

Discussion

Rapamycin/cyclosporin administration allows persistent opsin expression and light-evoked muscle activation. As all existing clinically approved AAV-mediated gene therapies require initial immune suppression, this requirement is not a barrier to clinical translation of an optogenetics-based therapy for OSA.
O050 Regional electromyographic activity in genioglossus during quiet breathing in supine, awake individuals with and without sleep apnoea
Authors: Yeung J , Brown E , Burke P , Jugé L , Knapman F , Chiang A , Eckert D , Butler J , Bilston L
Published: December 2024

Introduction

Inspiratory-related genioglossus electromyography (EMG) activity is crucial to maintain upper airway patency during inspiration. Recent findings suggest variations in anterior/posterior genioglossus multiunit EMG activation during awake supine quiet breathing in healthy adults. However, whether such differences extend to EMG across oblique (middle) and horizontal (base) genioglossus compartments, and whether activation differ in obstructive sleep apnoea (OSA) is unclear.

Methods

Prior to in-lab polysomnography, intramuscular electrodes were placed into the horizontal and oblique compartments of the genioglossus in 9 controls (AHI≤5 events/hr) and 45 age- and BMI- matched OSA patients (AHI range 5-94.3 events/hr). Multiunit EMG patterns were classified as phasic or tonic during awake supine quiet nasal breathing. Phasic pattern recordings were quantitatively analysed (% maximum of swallowing or tongue protrusion). The effects of OSA status and genioglossus compartments were assessed through mixed linear analysis, controlling for nadir Pepi and repeated measures in participants.

Results

More than half (57.6%, n=106/184) of the recording sites had a phasic pattern. A more negative nadir Pepi correlated with reduced likelihood of tonic activity (OR: 0.819, P=0.042). Within phasic patterns, a more negative nadir Pepi correlated with increased peak EMG (beta=-0.847, P=0.011), phasic EMG (beta=-0.654, P=0.005), and tonic EMG (beta=-0.253, P=0.048). No significant effects of OSA status or genioglossus compartment on activity patterns or EMG measurements were observed.

Conclusions

No compartmental disparity in EMG or differences between OSA and non-OSA individuals were found. Understanding mechanisms driving efficient dilatory activity of the genioglossus compartments is pivotal to develop OSA treatments targeting pharyngeal muscle activity.
O051 Understanding the uptake of non-invasive ventilation in motor neurone disease: results of a national survey
Authors: Graco M , Carey K , Russo K , Sheers N , Berlowitz D
Published: December 2024

Introduction

Non-invasive ventilation (NIV) is an effective therapy for extending survival and enhancing quality of life in people with motor neurone disease (pwMND). According to Australian registry data from 2005-2015, just 19% of pwMND ever commenced NIV. This study aimed to estimate the current rates of NIV uptake among pwMND and identify demographic factors associated with its uptake.

Methods

National cross-sectional survey. PwMND (or their carers) were invited to complete an online survey about their NIV use and health care experiences. Multivariate logistic regression modelling investigated associations between various demographic factors and NIV uptake.

Results

224 responses were received. Mean(SD) age was 64(11) years, 62% were male, median(IQR) time since diagnosis was 2(1-5) years. 46%(n=104) were using NIV; 6%(n=14) had started NIV and stopped; 4%(n=9) were referred and waiting to start; 3%(n=7) had declined NIV; 14%(n=32) had discussed NIV with a health care professional (HCP) but not been referred; and 26%(n=58) had never discussed NIV with a HCP. NIV uptake was significantly (p<0.05) associated with being male, residing in Victoria, residing in a metropolitan area, and longer time since diagnosis.

Conclusion

This study suggests that the uptake of NIV by pwMND in Australia is higher than previously reported, though registry-based cohort studies are needed to confirm this. Access to this highly effective therapy appears to be related to the person’s gender and where they live. A deeper understanding of the determinants and barriers to NIV uptake will enable targeted strategies that reduce health care inequity and improve outcomes for pwMND.
O052 Hypoxemia and arousals modulate nocturnal respiratory event-related cardiac function variations in obstructive sleep apnea patients
Authors: Ebrahimian S , Sillanmäki S , Rissanen M , Staykov E , Grote L , Bonsignore M , Baumert M , Leppanen T , Kainulainen S
Published: December 2024

Introduction

Obstructive sleep apnea (OSA) and its related consequences (i.e. desaturations or arousals) are known to immediately impact cardiac function. However, the dynamics of variations in heart function due to individual obstructive events and their consequences are not fully explored. We hypothesized that the respiratory events without immediate physiological consequences cause no post-event variations in cardiac function.

Methods

Variations in RR and rate-corrected QT (QTc) intervals were studied separately before, during, and after 4310 respiratory events from 134 OSA patients with no comorbidities (except diagnosed hypertension) or medications affecting heart function. Mixed-effect models were used to assess the impact of desaturation and arousal on cardiac function variations, independent of age, body mass index, sex, and diagnosed hypertension.

Results

In general, mean QTc intervals significantly (p<0.05) decreased during and increased after respiratory events compared to before events. Detailed analysis revealed that arousal (RR estimate= -23.6 millisecond, p<0.05; QTc estimate= 5.7 millisecond, p<0.05) or both desaturation and arousal (RR estimate= -33.0, p<0.05; QTc estimate= 8.4, p<0.05) modulated mean post-events RR and QTc intervals independently of confounding factors and between-subject variations, while desaturation alone affected only the RR interval (estimate= -9.4, p<0.05). In respiratory events without desaturation and arousal, mean post-event RR and QTc intervals showed no significant variation compared to before events.

Discussion

Respiratory events cause distinct cardiac responses if severe enough to cause desaturations and arousal. This indicates that the impact of respiratory events on cardiac function varies based on their immediate physiological consequences; without them, post-event cardiac variations are non-significant.
O054 Targeted ansa cervicalis nerve stimulation restores airflow to airway narrowing in obstructive sleep apnoea during propofol anaesthesia
Authors: Osman A , Carney A , Ooi E , Joshi H , Tran C , Hudson A , Catcheside P , Nguyen P , O’Reilly C , Gelekis N , Gibson D , Walsh J , Maddison K , Mackay S , Lewis R , Eckert D
Published: December 2024

Introduction

The pathophysiology of upper airway collapse in obstructive sleep apnoea (OSA) is multifactorial. Earlier animal and recent human data indicate that ansa cervicalis nerve stimulation may improve pharyngeal airflow via increased airway traction. We investigated a novel, targeted, neurostimulation approach of ansa cervicalis to improve upper airway function in people with OSA.

Methods

Participants with OSA (AHI>15 events/h) were administered drug-induced sleep endoscopy with propofol and equipped with a nasal mask connected to a pneumotachograph to measure airflow and a modified continuous positive airway pressure (CPAP) device. Ultrasound was used to identify and guide percutaneous insertion of a temporary multi-electrode array to target the ansa cervicalis nerve. Therapeutic CPAP was reduced to induce transient airflow limitation. Ansa cervicalis stimulation was applied at varying stimulus amplitudes and electrode configurations until optimised. Changes in peak inspiratory airflow (PIF) from therapeutic CPAP levels to transient CPAP reductions were compared without and with optimal ansa cervicalis stimulation.

Results

13 (3 female) predominantly non-obese (BMI=28±4Kg/m²) participants with OSA (AHI=38±16 events/h) aged 51±14 years (mean±SD) were studied. Preliminary findings in 10 participants show that 9/10 had increased PIF with 3.2±1.2mA stimulation. PIF at therapeutic CPAP was 0.37±0.13L/s. During CPAP reductions, PIF decreased to 0.18±0.13L/s (p<0.05) but returned to therapeutic CPAP levels (0.39±0.19L/s) during ansa cervicalis stimulation.

Conclusion

A novel, minimally-invasive, percutaneous stimulation approach to target the ansa cervicalis can markedly improve upper airway function during transient airway narrowing/closure in people with OSA during drug-induced sleep endoscopy.
O055 Fatigue risk in Search and Rescue operations: The challenge of sleep inertia and on-call work
Authors: Signal T , van den Berg M , Ladyman C
Published: December 2024

Introduction

Offshore Oil and Gas operations are normally supported by 24/7 Search and Rescue (SAR) services, which often involve fly-in-fly-out (FIFO) rosters. The current study followed SAR crew during two 21-day FIFO rosters to identify operational features that may increase fatigue risk.

Methods

Actigraphy was used to measure periods of sleep. At the start and end of each shift crew completed a 3-minute Psychomotor Vigilance Task and recorded ratings of fatigue and sleepiness. At the end of shifts workload ratings were made. Mixed model ANCOVAs were used to identify workplace factors associated with changes in fatigue, sleepiness and performance.

Results

Eighteen crew participated across 546 shifts. At the start of a shift, less prior sleep (p<.01) and less time awake (p<.001) were associated with greater fatigue and sleepiness. Fatigue and sleepiness were higher for shifts starting after 1500 (p<.01), whereas reaction time performance was slower for shifts starting before 0800 (p<.05). At the end of a shift, fatigue and sleepiness ratings were higher for longer shifts (p<.001), shifts with higher workload (p<.05), when crew had been awake longer (p<.05), or had been on-call the night prior (p<.05).

Discussion

A range of possible fatigue risks were identified. These included sleep inertia at the start of shifts, indicated by greater fatigue when time between waking and starting work was short. Being on call the night prior increased fatigue risk at the end of the next day’s shift. Through understanding where the fatigue risks are, an organization can ensure mitigations are appropriate.
O057 Sleep patterns and their associations with mental health and financial well-being in ride-hail drivers
Authors: Jaydarifard S , Smith S , Mann D , Rossa K , Shekari Soleimanloo S
Published: December 2024

Introduction

Driving is an activity where the need for sleep and work schedules can clash, with potentially severe consequences. Ride-hail drivers may be at particular risk, as characteristics of this form of precarious employment impact both sleep opportunity and the overall well-being of drivers. This study aimed to explore characteristic profiles of sleep in ride-hail drivers, and evaluated the relationships between these profiles and both mental health and financial well-being.

Methods

One hundred ride-hail drivers (12% female) completed an online survey assessing their perspectives on their working conditions, financial well-being (assessed by the 5-item financial well-being scale), and various aspects of their health, including sleep duration, sleep quality (assessed by the PROMIS sleep disturbance scale (SF-4a)), and mental health (two-item PROMIS Global Mental Health). Latent Profile Analyses, utilizing both sleep duration and quality, were used to categorise participants into two distinct sleep profiles, poor sleepers (36%) and good sleepers (64%). A binary logistic regression model was then employed to investigate the predictors of these sleep profiles.

Results

Poor mental health was associated with an odds ratio of 0.34 (95% CI: 0.17, 0.65) for the poor sleep profile. Lower financial well-being was associated with an odds ratio of 0.51 (95% CI: 0.27, 0.95) for the poor sleep profile.

Discussion

These results support a relationship between mental health, financial well-being, and poor sleep among ride-hail drivers. These findings may contribute to more effective policies that address both the unfavourable working conditions and sleep quality of ride-hail drivers.
O058 Sleep estimates from an under-mattress sensor can predict vigilance, working memory, and mental arithmetic performance
Authors: Manners J , Scott H , Guyett A , Stuart N , Catcheside P , Kemps E
Published: December 2024

Introduction

Sleep is vitally important to maintain cognitive function. Sleep trackers can reliably estimate several sleep metrics to help predict cognitive performance, but associations between sleep-tracker estimated sleep and cognitive domains are unclear. This study examined associations between sleep tracker-estimated sleep and next-day cognitive performance across several domains, including vigilant attention, working memory, and risky decision-making.

Methods

Twenty four participants (mean[SD] age=28[9] years, 12/12 male/female) attended the sleep laboratory twice for 8-day simulated shift-work experimental protocols under two lighting conditions (dim, blue-depleted vs. blue-enriched circadian-informed lighting). Following a baseline sleep, participants remained awake for 27h and transitioned to sleeping between 10:00-19:00 and undertaking cognitive tasks from 00:00-08:00 for four days. Cognitive tasks included the Digit-Symbol Substitution task (DSST), Continuous Performance task, Iowa Gambling task, Operation Span task, Psychomotor Vigilance test (PVT), and Stroop task. Sleep was assessed using an under-mattress sensor (Withings Sleep Analyzer). Mixed effects and random forest models tested associations between estimated sleep and cognitive performance.

Results

Significant associations were found between sleep metrics and PVT reaction time (R²=.13, p=.008), Operation Span arithmetic errors (R²=.15, p=.023), proportion correct on DSST and Stroop tasks, (R²=.06, p=.045; R²=.09, p=.003), and Stroop reaction time (R²=.19, p=.004). Random forest models demonstrated strong associations between cognitive performance and estimates of sleep architecture, snoring, and cardiovascular estimates.

Conclusion

Sleep trackers can help predict next-day cognitive performance, particularly in vigilance, working memory, and mental arithmetic. This may be a practical strategy to help manage sleep-related cognitive impairments and enhance worker safety in shift work conditions.
O061 Living with narcolepsy and driving in Australia: Exploring lived experience and clinician perspectives
Authors: Schokman A , Cheung J , Milton A , Naehrig D , Thornton N , Bin Y , Kairaitis K , Glozier N
Published: December 2024

Introduction

Narcolepsy is a rare neurological sleep disorder. International data suggests a large proportion of persons with narcolepsy experience symptoms that impact their driving (e.g. EDS, cataplexy, microsleeps, fatigue). Driving and narcolepsy has not been explored within the context of the Australian regulatory system.

Methods

24 adult persons with narcolepsy (PwN) and 12 clinicians participated in semi-structured interviews exploring the lived experience of narcolepsy in Australia. A sub-study explored responses around driving ability, regulation, and therapeutic relationship; analysed thematically by a multidisciplinary team.

Results

Preliminary results suggest PwN acknowledge the impact symptoms have on driving, including how feeling tired/fatigued led to increased risky behaviour (e.g. speeding to get home faster and avoid falling asleep at the wheel). Yet most believed narcolepsy did not affect their ability to drive or hold an unrestricted license. This dissonance appears driven by fear of loss of license, associated personal/economic hardship and fear of being vulnerable when asleep on public transport. Most PwNs were unaware of state-based regulatory requirements around diagnosis disclosure and reported their clinicians had not raised this issue. Conversely, not all clinicians appeared aware of regulations and spoke of difficulties broaching the topic, its impact on the patient-physician relationship, and limited resourcing to organise objective measures of driving ability.

Discussion

Our results suggest increased awareness for all parties is needed around the risks/implications of driving with narcolepsy and regulatory disclosure. Better-quality information, support, and regulatory guidance around fitness to drive would likely help PwN and clinicians navigate this space.
O063 Cognitive behavioural therapy for insomnia improves obstructive sleep apnoea severity, but not any of the endotype traits in those with comorbid insomnia and sleep apnoea (COMISA)
Authors: Brooker E , Landry S , Edwards B , Drummond S
Published: December 2024

Background

Evidence suggests cognitive behavioural therapy for insomnia (CBT-I) improves obstructive sleep apnoea (OSA) severity in those with comorbid insomnia and sleep apnoea (COMISA), though the mechanisms behind this change are unstudied. CBT-I, which promotes sleep continuity and reduces hyperarousal, may improve OSA by raising the respiratory arousal threshold, a key OSA endotype trait. We aimed to replicate prior findings on CBT-I improving OSA severity and investigate its impact on the arousal threshold.

Methods

In a single-arm trial, we recruited 20 patients (11M:9F; Mage = 53.48, SDage = 9.42 years) with comorbid insomnia and OSA defined by an apnoea hypopnea index (AHI) ≥ 10 events per hour. Overnight sleep studies were conducted before and after seven weekly sessions of CBT-I over telehealth with a psychologist to measure OSA severity and sleep architecture. The arousal threshold and other endotype traits were assessed via the ventilation flow signal from polysomnography.

Results

There was a significant 8.9 event/h reduction in the AHI following CBT-I 95%CI[3.48, 14.49], p =.003, to a moderate effect (d = 0.52). There was no change in the arousal threshold, the other endotype traits, nor was the change in arousal threshold associated with the change in the AHI (p >.05).

Conclusions

In these preliminary findings, we provide further support CBT-I improves OSA severity. Despite the reduction in the AHI, there was no change in the arousal threshold. These results underscore the importance of managing insomnia in COMISA, with further research needed to elucidate why CBT-I improves OSA severity.
O064 Tirzepatide reduced sleep apnea severity in adults with obstructive sleep apnea and obesity: results from the SURMOUNT-OSA trial
Authors: Grunstein R , Malhotra A , Fietze I , Wever T , Dunn J , Chakladar S , Bunck M , Bednarik J
Published: December 2024

Introduction

We aimed to investigate the efficacy and safety of tirzepatide in treating moderate-to-severe obstructive sleep apnea (OSA) in adults with obesity.

Methods

SURMOUNT-OSA (NCT05412004) was a randomized, 52-week phase 3 trial comparing the efficacy and safety of tirzepatide to placebo in adults living with moderate-to-severe OSA and obesity. Under a master protocol, the trial involved Study 1, (participants who were unable or unwilling to use positive airway pressure (PAP), and Study 2, (participants who were and planned to stay on PAP therapy during the trial). 469 participants were randomised in a 1:1 ratio to receive tirzepatide maximum tolerated dose (MTD) 10 or 15 mg once weekly, or placebo.

Results

Baseline AHI (apnea-hypopnea index) and BMI were 50.1 events/h and 38.8 kg/m2. At 52 weeks, tirzepatide led to a mean AHI reduction from baseline of 27.4 (55.0%) and 30.4 (62.8%) events per hour compared to 4.8 (5.0%) and 6.0 (6.4%) events per hour for placebo in Study 1 and Study 2, respectively. Tirzepatide led to a mean weight reduction from baseline of 18.1% and 20.1%, compared to 1.3% and 2.3% for placebo, in Study 1 and Study 2, respectively. The most commonly reported adverse events in SURMOUNT-OSA studies were gastrointestinal-related and generally mild to moderate in severity in keeping with previous studies.

Discussion

Tirzepatide significantly reduced the AHI compared to placebo in adults with moderate-to-severe OSA and obesity, with and without PAP therapy, and therefore may represent a therapeutic option for this patient group.
O067 Personalisation of comfort settings on CPAP devices using machine learning
Authors: Wimms A , Emami H , Liu N , Sadr N , Pongrass S , Gupta C , McGann S , Tan Y , Sopha T , Yan Y , Nguyen C
Published: December 2024

Introduction

Machine learning (ML) technology provides a novel mechanism to identify patterns in large data sets, draw inferences and develop algorithms to simplify complex problems. Sleep apnea is a uniquely positioned health condition in the ML space due to the large amounts of data collected by diagnostic and CPAP devices.

We developed, validated, and tested a ML model which recommends personalised combinations of CPAP comfort settings for new users.

Methods

Data sets from 718,421 anonymous OSA patients were used to develop the ML models. Our ML method adopted the Doubly-Robust Learner to estimate the effect of comfort settings combinations on CPAP compliance. A multilayer perceptron model has been developed at each stage of the DR-learner method to provide the propensity model and the outcome models.

A clinical trial was then conducted to measure the impact of the model on patient outcomes.

Results

Development and validation of the ML models, utilising observational data, demonstrated a promising capability to enhance CPAP compliance through suggesting personalised comfort settings.

A double-blinded, RCT was conducted on 58 patients with newly diagnosed OSA. 30 days after setup, more patients in the ML model group were still using CPAP compared with the control group (96% vs 80%, p=ns).

Discussion

We developed and validated a unique machine learning algorithm aimed at providing personalised comfort CPAP settings in an area where limited guidance currently exists. This pilot study has shown that the ML model may provide benefit to new CPAP patients.
O068 Vascular and Autonomic Function in Comorbid Insomnia and Sleep Apnoea
Authors: Tong B , Stewart G , Flood J , de Chazal P , Cistulli P
Published: December 2024

Comorbid insomnia and sleep apnoea (COMISA) is a common sleep disorder and may be associated with increased cardiovascular risk. This study aimed to compare polysomnography-derived biomarkers of cardiovascular risk in patients with COMISA, obstructive sleep apnoea (OSA) only, insomnia only, and without OSA or insomnia.

Patients were identified from the Sydney Sleep Biobank database. Insomnia was defined as a positive test on the Insomnia Symptom Questionnaire (self-report of poor sleep and daytime impairment at least three times per week for four weeks). COMISA was defined as having insomnia and an apnoea-hypopnoea index >5 events/h. Heart rate variability (HRV) during stage N2 sleep and pulse wave amplitude drop (PWAD) parameters were derived from the electrocardiograms and plethysmography signals of polysomnograms, and compared between groups.

To date 471 patients (median[IQR] age: 50[37, 62] years; 62% males) have been analysed. Forty-two percent of patients had OSA only, 22% had insomnia only, 23% percent had COMISA and 14% did not have OSA or insomnia. Patients with COMISA had lower HRV measures (SDNN, P=0.0218; Total Power, P=0.046; pNN50%, P=0.044; absolute low frequency power, LF, P=0.0034). After adjusting for age, sex and BMI, these metrics were not significant (P >0.05). PWAD frequency and duration were similar between groups (P >0.05).

These preliminary data indicate patients with COMISA have altered cardiovascular autonomic function specifically reduced parasympathetic modulation indicated by lower pNN50%, Total Power and LF. This finding supports previous work demonstrating elevated cardiovascular risk in patients with COMISA, although age, sex, and BMI may be potential mediators.