Depressive symptoms are associated with poor sleep quality rather than apnea-hypopnea index or hypoxia during sleep in patients with obstructive sleep apnea

We examined factors, including the severity of obstructive sleep apnea (OSA), that were associated with depressive symptoms and excessive daytime sleepiness in OSA patients. We retrospectively reviewed data of 1203 subjects (861 men, mean age 48.2 years) who completed self-reported questionnaires and underwent polysomnography between September 2005 and May 2016 at the Center for Sleep and Chronobiology at Seoul National University Hospital. We compared scores on the Beck Depression Inventory (BDI) and Epworth sleepiness scale (ESS) between OSA and control groups. Analyses for OSA subgroups were classified by severity, and partial correlations were performed. BDI scores were higher in the OSA than in the control group (12.3 +/- 7.6 vs. 10.1 +/- 6.2, p = 0.001). There were differences in ESS scores among the mild, moderate, and severe OSA subgroups (p < 0.001), but not in BDI scores (p = 0.236). After adjusting for age, gender, and BMI, BDI in the OSA group correlated positively with wake after sleep onset (WASO; p = 0.014) and sleep latency (SL; p < 0.001), negatively with total sleep time (TST; p < 0.001) and sleep efficiency (SE; p = 0.001), but not with the apnea-hypopnea index (AHI; p = 0.387) or average O-2 (p = 0.542). ESS in the OSA group correlated positively with TST (p < 0.001), SE (p < 0.001), and AHI (p < 0.001) and negatively with WASO (p = 0.010), SL (p < 0.001), and average O-2 (p < 0.001). In this study, patients with OSA had more depressive symptoms than those without OSA. Daytime sleepiness in OSA patients was related to the severity of OSA as well as sleep propensity. However, depressive symptoms in OSA patients were associated with poor sleep quality rather than OSA severity. Depressive symptoms in OSA may be treated by modulating the sleep architecture and sleep quality.