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)

Abstract 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.