Abstract
STUDY OBJECTIVES: Cognitive behavioral therapy for insomnia (CBT-I) improves obstructive sleep apnea (OSA) severity in comorbid insomnia and sleep apnea, though the mechanisms underlying this change are unstudied. CBT-I, which promotes sleep continuity and reduces hyperarousal, may improve OSA by raising the respiratory arousal threshold. We aimed to investigate the effect of CBT-I on OSA severity and its impact on the arousal threshold and other endotype traits. METHODS: In this single-arm trial, 25 patients with comorbid insomnia and sleep apnea (13 females and 12 males, mean age [standard deviation] = 53.7 [8.7] years) completed a 7-week individual CBT-I program. Patients met diagnostic criteria for insomnia and demonstrated an apnea-hypopnea index (AHI) ≥ 10 events/h (mean AHI [standard deviation] = 35.2 [16.4] events/h). Overnight polysomnography before and after CBT-I measured OSA severity, sleep architecture, and the 4 OSA endotypes (ie, collapsibility, muscle compensation, loop gain, and arousal threshold). RESULTS: There was a 7.7 ± 10.2 events/h reduction in the AHI from baseline to posttreatment (P = .001) but no change in any of the OSA endotype traits studied (all P > .05). Secondary analyses showed a relationship whereby increases in stage N3 sleep were associated with decreases in AHI (r(2) = .19, P = .03). Significant improvements were also found in insomnia severity and sleep diary-based sleep efficiency, sleep onset latency, and wake after sleep onset at posttreatment (all P < .001). CONCLUSIONS: CBT-I is beneficial in improving insomnia symptoms and we provide further support CBT-I improves OSA severity. Despite no change in the OSA endotype traits, the improvement in the AHI may be associated with increased amounts of stage N3 sleep. These results underscore the importance of managing insomnia in comorbid insomnia and sleep apnea. CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trial Registry; Name: Project COMISA (Comorbid Insomnia and obstructive Sleep Apnea): A study investigating the effect of cognitive behavioral therapy for insomnia (CBT-I) on obstructive sleep apnea severity and cognitive functioning in patients experiencing COMISA; URL: http://www.anzctr.org.au/; Identifier: ACTRN12622000226707. CITATION: Brooker EJ, Landry SA, Genta PR, Abdelmessih GT, Edwards BA, Drummond SPA. Cognitive behavioral therapy for insomnia is associated with reduced sleep apnea severity but not its endotype traits in those with comorbid insomnia and sleep apnea. J Clin Sleep Med. 2025;21(6):1041-1051.