0620 CPAP Effects on Self-Reported Outcomes, Attention, and Actigraphy- and Heart Rate–Derived Circadian Metrics: A Randomized Trial

Abstract Introduction Continuous positive airway pressure (CPAP) improves sleepiness and quality of life, but its cognitive effects remain inconsistent, and its influence on circadian regulation is poorly understood. We examined the effects of CPAP on self-reported outcomes, attention, and circadian patterns derived from both activity/rest cycles and heart-rate (HR) rhythms. Methods Adults with obstructive sleep apnea were randomized (1:1) to 12 weeks of CPAP or inactive control. Assessments included self-reported sleepiness (Epworth Sleepiness Scale), anxiety/depression (Hospital Anxiety and Depression Scale), sleep quality (Pittsburgh Sleep Quality Index; Insomnia Severity Index), health-related quality of life domains (Short Form-36), attention (Psychomotor Vigilance Task [PVT]; Digit Symbol Substitution Test [DSST]), and circadian metrics (mesor, amplitude, peak, period) derived from 7-day actigraphy-based rest/active patterns and hourly HR rhythms. CPAP effects were estimated as baseline-adjusted between-group differences controlling for age, sex, body mass index, and apnea–hypopnea index using an intention-to-treat framework, with a completer sensitivity analysis. Results Fifty-two participants were randomized and 45 completed follow-up. Compared with control, CPAP improved physical functioning and mental health at week 4. At week 12, CPAP reduced sleepiness, enhanced vitality, improved DSST performance (correct responses), shortened mean reaction time, and advanced circadian peak timing derived from both actigraphy and HR measures. No significant effects were observed for anxiety/depression, sleep quality, PVT lapses or reaction time, or other circadian parameters. Conclusion CPAP improved sleepiness, select quality-of-life domains, attention, and specific circadian features, whereas sleep quality and mood symptoms showed no measurable benefit. These findings highlight potential short-term cognitive and circadian responsiveness to CPAP, but their clinical implications require further study. Support (if any) National Science and Technology Council, Taiwan (NSTC 113-2314-B-002 -284 -MY3; 111-2314-B-002-293); NTHU 109-42, 111-S0298, 111-X0033,113-S0286National Taiwan University Hospital (NTHU 109-42, 111-S0298, 111-X0033, 113-S0286).