Does CPAP therapy affect sleep time in patients with obstructive sleep apnea? A prospective study

Background: It is currently unknown whether and how treating obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) affects habitual sleep time. Objectives: To investigate the effect of CPAP on habitual sleep time. Methods: Fifty-seven OSA patients (AHI >20) were prospectively enrolled and were evaluated before and after 3 mo of CPAP. Measurements included polysomnography, habitual sleep on 7 consecutive days assessed by actigraphy with sleep diary, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index (PSQI). Results: Post-CPAP habitual night sleep time did not change compared to the baseline (pre 352 ± 65, post 351 ± 57 min, p = 0.94). The responses to CPAP varied among the participants; sleep time increased by 34 ± 25 min in 27 participants and decreased by 31 ± 29 min in 30. In the exploratory analysis comparing sleep time restorers with non-restorers, the former group was characterized by shorter habitual sleep time (328 ± 68 vs 372 ± 55 min, p = 0.01), more frequent daytime napping (79 vs 40%, p = 0.04), lower sleep efficiency (76.7 ± 10.8 vs 82.7 ± 5.8%, p = 0.01), and higher arousal index (43.5 ± 22.2 vs 34.0 ± 13.9, p = 0.06) in the baseline whereas the latter was associated with more frequent hypnotics use (11 vs 40%, p = 0.02). CPAP mainly improved daytime symptoms (reduced daytime sleepiness and napping) in the sleep time restorers whereas improvements in sleep quality (increased deep sleep and reduced PSQI) were noted in the non-restorers. Conclusions: CPAP therapy did not prolong habitual night sleep in OSA patients in the entire group. However, responses to CPAP differed among OSA patients with different clinical phenotypes.