Rationale: Obstructive sleep apnea (OSA) can affect not only sleep quality but also sleep duration. Determining the therapeutic effects of continuous positive airway pressure (CPAP) on habitual sleep profiles may shed light on the impact of OSA on sleep duration.
Objectives: To determine whether and how CPAP affects habitual sleep duration in patients with OSA.
Methods: Assessments of sleep duration and sleep quality were performed on 57 newly diagnosed study subjects with OSA (46 men; median age, 63 yr; apnea-hypopnea index, >20 h-1) at baseline and 3 months after initiation of CPAP therapy. Measurements included in-laboratory sleep tests (polysomnography), assessments of habitual sleep (actigraphy with sleep diary for 7 d), and questionnaires on subjective symptoms (Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, and Hospital Anxiety and Depression Scale).
Results: Actigraphic night sleep time did not change after CPAP (from 354.0 ± 64.5 min to 353.0 ± 57.0 min; P = 0.87) in the entire group, despite improvements in sleep efficiency and sleep fragmentation. Changes in habitual night sleep duration varied among the participants; habitual night sleep duration increased by 33 minutes (interquartile range, 14-45 min) in 28 participants (sleep time restorers) and decreased by 23 minutes (interquartile range, -48 to -11 min) in 29 participants (sleep time nonrestorers). Subgroup analyses revealed that sleep time restorers were characterized at baseline as having shorter and more fragmented sleep with frequent daytime napping. Nonrestorers were characterized by frequent use of hypnotic drugs and comorbid insomnia, despite longer habitual sleep duration. Actigraphic sleep fragmentation, sleep efficiency, daytime sleepiness, and the frequency of daytime napping were improved after CPAP only in the sleep time restorers, whereas subjective sleep quality was improved in the nonrestorers. Multivariate linear regression showed that shorter baseline night sleep time, baseline daytime napping, and percentage of sleep time under CPAP were positive predictors of the restoration of actigraphic night sleep time, whereas hypnotic use was a negative predictor.
Conclusions: Short-term CPAP did not affect habitual night sleep duration in the group as a whole but induced intraindividual changes in relation to phenotypic features of OSA. Clinical trial registered with www.umin.ac.jp (UMIN000012639).
Keywords: actigraphy; phenotype; sleep habit; sleep quality; sleep time.