Abstract Introduction Auto-titrating positive airway pressure (APAP) is commonly used in children starting CPAP treatment, with remote data monitoring used to assess initial pressure requirements. We aimed, over the first month of treatment, to 1) detail initial APAP settings 2) compare adherence in children who required pressure changes to those who did not; and 3) determine if titration polysomnography is necessary. Methods Retrospective review of children commencing APAP from 2020-2024, including: initial APAP prescription, setting changes in the first 4 weeks, adherence during weeks 3&4 of treatment, and recommended settings changes after titration polysomnography. Results 131 children commenced APAP (29%F; median 12.9y, range 2.7-19.6y; 79% overweight or obese; 49% other comorbid condition). Median (range) initial minimum APAP pressure was 4 (4-6)cmH2O, and maximum 10 (6-20)cmH2O. 55 (42%) required 1 or more pressure changes and this group had better adherence during the first month of acclimatisation (93% vs 61% nights used (p<.001); hours of use [days used] 7.5h vs 4.1h (p<.001)). 74 had a titration polysomnography, with a recommended prescription change in 44 (59%). Pressure changes during acclimatisation did not predict recommendation for change following titration polysomnography (p=.56). Discussion Change to APAP settings over the first month of treatment is associated with better adherence, but the direction of this relationship is unclear. Despite changes to APAP settings in the first month, additional changes were recommended after 59% of APAP titration polysomnography, highlighting the role for titration in a subgroup of patients; further research is required to better define those who benefit most.

Abstract Background Depression is the leading cause of non-fatal disease burden worldwide, with disturbances in the circadian system commonly observed in affected individuals. Selective serotonin reuptake inhibitors (SSRIs), a first-line treatment for depression, significantly enhance the circadian system’s sensitivity to light. The benefits of this increased sensitivity may depend on the balance between beneficial daytime light exposure and adverse night-time brightness. Method This case study explored whether variability in healthy light exposure patterns - more daytime light and less night-time light - related to SSRI treatment efficacy. A 27-year-old female patient experiencing depression underwent an 8-week intervention with citalopram, the most commonly prescribed SSRI. Light exposure was monitored using a custom wearable spectrophotometer, which continuously recorded exposure to light across the entire visible spectrum. Mood was assessed fortnightly using the Montgomery-Asberg Depression Rating Scale (MADRS). Results At baseline, the patient had a MADRS score of 29, indicating moderate depression (range: 20-34). During the intervention, healthier light exposure patterns - brighter daytime light and minimal light at night - aligned with improved mood over this period. By the final assessment, their MADRS score had decreased to a level consistent with mild depression (range: 7-19). Discussion Healthy light exposure patterns are known to strengthen circadian rhythms. Our findings highlight the potential for promoting healthier light exposure to optimise antidepressant treatment efficacy and improve treatment outcomes in depression.

Abstract Objectives This study investigated cross-country differences in infant and maternal sleep across Korea, the U.S.A., and Australia. Methods Participants were 2005 mother-infant dyads (infant Mage = 13.82 months, SDage = 6.23 months) from Australia (n = 73), Korea (n = 222), and the U.S.A. (n = 1710). Mothers completed the Insomnia Severity Index, Dysfunctional Beliefs and Attitudes About Sleep, and the Brief Infant Sleep Questionnaire – Revised postpartum and were grouped (6, 12, and 24 months) dependent on infant age. Data were analysed using multiple regressions. Results Korean mothers had higher insomnia symptoms compared to Australian and U.S.A. mothers at all timepoints (p’s < .002). Mean DBAS scores were higher for Korean compared to U.S.A. and Australian mothers (p’s < .007). Compared to U.S.A. infants at all timepoints and to Australian infants at 12- and 24 months, Korean infants had shorter nighttime TST (p’s < .040) and longer SOL (p’s < .003). Bedsharing was associated with lower insomnia symptoms in Korean mothers at 24 months (p=.043). Co-sleeping was not significantly associated with insomnia and DBAS scores (p’s > .164). Conclusions Korean mothers had higher insomnia and DBAS scores, which did not differ by co-sleeping status; Korean infants had shorter nighttime TST, and longer SOL. Bedsharing in Korea was protective against insomnia symptoms at 24 months. Further exploration into the mechanisms of sleep changes is required to tailor future interventions for diverse backgrounds.

Abstract Introduction Protective masks are used in the prevention of respiratory virus transmission. Mask safety is well documented in healthy individuals but is unclear in people with chronic hypercapnic respiratory failure (CHRF). Additionally, masks are often poorly tolerated in this population. This study assessed the effect of surgical masks and N95 masks in people with stable CHRF using non-invasive ventilation (NIV). Methods A randomised cross-over trial was performed. SpO2 and transcutaneous CO2 (PtcCO2) were measured in participants wearing a surgical mask, an N95 mask and no mask for 20-minute periods at rest. Secondary outcomes included heart rate, respiratory rate, the A1 scale from the Multidimensional Dyspnoea Profile (MDP) and the modified Borg dyspnoea scale (mBORG). Results 24 participants (50% female; mean (SD) age 61 (13) years) participated. The surgical and N95 masks had negligible effects on SpO2, PtcCO2, heart rate and respiratory rate across the 20-minute study period. Masks increased the mBORG (surgical mask median difference 0.75 points [95% CI 0.25 to 2.00]; N95 mask median difference 1.25 [95% CI 0.75 to 2.00]) and MDP (surgical mask median difference 1.5 points [95% CI 0.5 to 2.5]; N95 mask median difference 2.0 points [95% CI 1.0 to 3.0]). Discussion Wearing a surgical or N95 mask did not significantly affect gas exchange in patients with CHRF using NIV. However, dyspnoea and breathing discomfort did increase.

Abstract Background and objective Nocturnal pulse oximetry (NPO) is a simple and inexpensive assessment tool that has previously been shown to correlate with prognosis and timing of non-invasive ventilation (NIV) initiation in people living with motor neuron disease (plwMND). However, the optimal number of nights for measuring NPO has not been defined for this population, with other respiratory conditions exhibiting both low and high night-to-night variability in NPO parameters. This study aims to determine the inter-night variability in NPO data over three nights in plwMND. Methods We conducted a retrospective analysis of 132 studies in which plwMND underwent three consecutive nights of NPO. Intraclass correlation coefficients (ICC) were used to assess the reliability of key NPO parameters, including mean percentage of total recording time with oxygen saturation (SpO₂) <90% (T90), oxygen desaturation index (ODI), basal SpO₂, and nadir SpO₂. The proportion of plwMND meeting NIV criteria based on single-night versus multi-night assessments was also compared. Results Excellent reliability was observed for T90 (ICC(1) = 0.940) and ODI (ICC(1) = 0.901), while basal SpO₂ (ICC(1) = 0.845) and nadir SpO₂ (ICC(1) = 0.768) demonstrated good reliability. However, relying on a single-night NPO assessment failed to identify 12% of plwMND who met NIV criteria when evaluated over three nights. Conclusion Despite good to excellent inter-night variability of NPO data in plwMND, multi-night NPO monitoring improves the accuracy of identifying plwMND requiring NIV. These findings support the need for multi-night assessments to enhance clinical decision-making in MND management.

Abstract Introduction Measuring circadian timing informs the diagnosis of Insomnia and Delayed Sleep–Wake Phase Disorder (DSWPD) in adults, however this has not been studied in adolescents. This study examined circadian timing of sleep in adolescents, including those meeting diagnostic criteria for insomnia and DSWPD. Methods Participants were a community sample of adolescents (n = 125, age M ± SD = 13.52 ± 1.04) who completed a diagnostic sleep interview (SCISD) to assess whether they met subthreshold or threshold insomnia or DSWPD criteria. Participants completed two weeks of sleep–wake monitoring during school term, with circadian phase measured via salivary dim light melatonin onset [DLMO] on the last Friday of sleep monitoring. Results Twenty (16%) adolescents met insomnia criteria (n = 7 threshold, n = 13 subthreshold), 14 (11.2%) DSWPD criteria (n = 9 threshold, n = 5 subthreshold), and 91 (72.8%) did not meet any criteria for either. In adolescents who met insomnia criteria, DLMO occurred at 20:57h ± 1.16 (range 18:56–00:00h), with sleep onset occurring 1.73h ± 1.31 after DLMO (range -1.78- 3.5h). In adolescents who met DSWPD criteria, DLMO occurred at 21:05 ± 1.12 (range 19:17–23:43h), with sleep onset occurring 2.38h ± 1.18 after DLMO (range 0.44-4.02h). For those who met no criteria for either condition, DLMO occurred at 20.60 ± 1.22 (range 18.02-23.68h), with sleep onset occurring 1.97 ± 1.22 after DLMO (range -1.54-5.67h). Twelve participants initiated sleep before or within 30 minutes of their DLMO time (n = 2 insomnia, n = 2 DSWPD, n = 8 no symptoms). Discussion We observed large inter-individual variability in circadian timing and phase angle in adolescents meeting diagnostic criteria for insomnia and DSWPD, indicating limited differentiation in circadian timing using diagnostic interviews.

Abstract Background Sleep related hypoventilation is deadly, complex to diagnose and very treatable. It is caused by medical comorbidities, such as obesity, opiate medications and rare neuromuscular conditions. Transcutaneous carbon dioxide monitoring during polysomnography is the gold standard to diagnose sleep related hypoventilation. There is currently no strong evidence base for when to do transcutaneous carbon dioxide monitoring. The aim of the study is to identify which baseline clinical measures are most accurate at identifying nocturnal hypoventilation. Methods This study will review the results of 200 adult, type 1 polysomnograms which included transcutaneous carbon dioxide monitoring from the year 2024 at a single, tertiary institution. All CPAP and NIV titration studies will be excluded. Data collection will include patient demographics of age, gender, the presence of hypoventilation and 14 clinical predictors, including known aetiologies/comorbidities, awake oxygen saturation, BMI and previous history of or awake hypercapnoea. Progress to Date This project is currently in the data collection phase. Intended outcome and impact Logistic regression will be used to identify the clinical measures most predictive of hypoventilation, evaluating individual and combined measures for accuracy. As sleep services shift to increasing home-based diagnostics, which cannot diagnose hypoventilation, it is important that this diagnosis is not missed. Thus, this study is important to help identify those patients in the clinic at highest risk of hypoventilation, to ensure that this diagnosis is detected.

Abstract Introduction Non-invasive ventilation (NIV) is a standard treatment for chronic ventilatory failure from various conditions. However, long-term NIV can lead to complications, including structural changes in the facial skeleton. The nasal valve area is particularly susceptible to external pressure. This report presents a rare case of lateral nasal bone loss secondary to prolonged NIV use. Case Description A 42-year-old obese male (350–400 kg) was started on NIV for obesity hypoventilation syndrome (S/T IPAP 35 cm H₂O, EPAP 25 cm H₂O, Ti 1.6, BUR 18/min). His usage increased from 8 hours nightly to up to 20 hours/day between 2019 and 2025. He developed progressive nasal bulging during NIV use. Examination revealed a non-tender bulge near the eye. ENT evaluation confirmed bilateral lateral nasal bone loss. Nasendoscopy showed nasal dryness and nasopharyngeal crusting. Due to his high BMI, CT imaging was not feasible, and surgery posed high risk. A custom nasal prosthesis was fitted. Current management includes daytime mouthpiece ventilation and night-time NIV with a nasal splint. Discussion This case illustrates the challenges of diagnosing and managing nasal bone loss in chronic NIV users. The mechanism likely involves pressure-induced bone resorption, influenced by mask fit and bone fragility. Constant pressure may disrupt bone remodelling, causing resorption and soft tissue deformation. Conclusion Long-term NIV patients require careful monitoring for nasal complications. Regular mask fit assessments and exploring alternative interfaces can reduce risk. Custom solutions like 3D-printed masks may offer personalized care and minimize complications.

Abstract Introduction Poor sleep affects up to 45% of Australians, with regional populations facing significant barriers to sleep services. In Queensland, where over a third of the population resides outside metropolitan areas, these inequities are particularly evident. This project assessed the feasibility and acceptability of a telehealth-led, regionally delivered sleep service pathway in Rockhampton—a major centre lacking a public sleep service. Methods Over 12 months, a sleep care pathway was implemented for patients with suspected sleep disorders, principally sleep-disordered breathing. This was governed by the Royal Brisbane & Women’s Hospital, 637 km away, and delivered via telehealth with local provider support. Outcomes included feasibility, acceptability, and preliminary effectiveness, measured by recruitment, retention, adherence, and satisfaction. Results Eighty-four patients were referred; 69 attended their initial appointment demonstrating a service uptake of 82%. Of these, 30 (36%) were triaged directly to level-II polysomnography due to high pre-test probability of obstructive sleep apnoea (OSA). Moderate to severe OSA was present in 60.9% (n = 25/41) of the patients studied. 51 patients (60.7%) were initiated on CPAP therapy and 3 progressed to testing for hypersomnolence. The pathway showed strong recruitment, good attendance to diagnostic and treatment steps. Patient satisfaction was high, particularly with accessibility and convenience. Clinicians reported positive engagement, supporting integration into standard practice. Discussion This study demonstrated a feasible, scalable model for delivering sleep care in regional Queensland. By overcoming geographic barriers, the pathway improved access and efficiency. The model holds strong potential for replication across other regions to enhance equity in health.

Abstract Introduction Sleep is the most effective recovery mechanism available to athletes; however, training, competition, and travel schedules all impact the amount and quality of sleep obtained, often in an inconsistent manner. The impact of sleep regularity on sleep duration and quality as well as health and performance-related outcomes in athletes remains largely unexplored. Therefore, the aims of this review were to determine the current state of knowledge concerning the impact of sleep regularity on sleep duration and quality as well as identify whether any evidence exists regarding the impact of sleep regularity on other important outcomes for athletes such as health, performance, and injury. Methods PubMed, Web of Science, PsycINFO, and Scopus databases were systematically searched. Results Database searching yielded 3943 results and 10 studies were eventually included in the review. Included studies investigated associations between sleep regularity and other sleep variables (n = 7), performance (n = 2), and mental health (n = 1). Discussion Athletes are an at-risk population for irregular sleep; however, the consequences of low sleep regularity have been scarcely investigated. Studies revealed inconsistent evidence on the association between sleep regularity and other measures of sleep duration, quality, and fragmentation. Preliminary evidence suggests that irregular sleep patterns negatively impact performance and mental health; however, gender appears to influence the nature of the associations. Research exploring how sleep regularity influences athlete health and performance should be prioritised so that appropriate management strategies can be developed and implemented.