Neurocognitive functioning in comorbid insomnia and sleep apnea patients is better after positive airway pressure therapy, but worse after cognitive behavioral therapy for insomnia: exploratory analysis of cognitive outcomes from the Multidisciplinary Approach to the Treatment of Insomnia and Comorbid Sleep Apnea study. Sleep STUDY OBJECTIVES:Neurocognitive impairments in comorbid insomnia and sleep apnea (COMISA) are not well documented. We explored neurocognitive functioning and treatment effects in individuals with COMISA as an ancillary study to a randomized clinical trial. METHODS:Participants with COMISA (n = 45; 51.1% female; mean age = 52.07 ± 13.29 years), from a 3-arm randomized clinical trial combining cognitive behavioral therapy for insomnia (CBT-I) and positive airway pressure (PAP) concurrently (CBT-I+PAP) or sequentially, completed neurocognitive testing at baseline, and post-treatment. Using Bayesian linear mixed models, we estimated effects of CBT-I, PAP, or CBT-I+PAP, compared to baseline, and CBT-I+PAP compared to PAP on 12 metrics across five cognitive domains. RESULTS:This COMISA sample had worse neurocognitive performance at baseline than reported for insomnia, sleep apnea, and controls in the literature, though short-term memory and psychomotor speed performance appears intact. When comparing PAP to baseline, performance on all measures was better after treatment. Performance after CBT-I was worse compared to baseline, and only performance in attention/vigilance, executive functioning via Stroop interference and verbal memory was better with moderate-high effect sizes and moderate probability of superiority (61-83). Comparisons of CBT-I+PAP to baseline generated results similar to PAP and comparing CBT-I+PAP to PAP revealed superior performance in only attention/vigilance via psychomotor vigilance task lapses and verbal memory for PAP. CONCLUSIONS:Treatment combinations involving CBT-I were associated with poorer neurocognitive performance. These potentially temporary effects may stem from sleep restriction, a component of CBT-I often accompanied by initially reduced total sleep time. Future studies should examine long-term effects of individual and combined COMISA treatment pathways to inform treatment recommendations. CLINICAL TRIAL:This was an ancillary study from a clinical trial (Multidisciplinary Approach to the Treatment of Insomnia and Comorbid Sleep Apnea (MATRICS), which was preregistered at www.clinicaltrials.gov (NCT01785303)). 10.1093/sleep/zsad128