Residual excessive daytime sleepiness in patients with sleep apnea syndrome receiving continuous positive airway pressure in Japan: A single-center study

Excessive daytime sleepiness (EDS) is a symptom of sleep apnea syndrome (SAS). In some patients with SAS who undergo continuous positive airway pressure (CPAP) therapy, EDS persists (residual EDS). However, knowledge of residual EDS in Japan is limited. Therefore, we examined EDS as defined by the Japanese version of the Epworth Sleepiness Scale (a score of ≥11) before and after long-term (≥1 year) CPAP therapy in 490 patients with SAS. Good adherence to CPAP therapy was defined as its use for at least 4 h during 70% of the nights. The prevalence of residual EDS was 9.4%. Residual EDS was negatively associated with good adherence to CPAP therapy. Furthermore, the longer the CPAP therapy duration after initiation, the lower the prevalence of residual EDS. Therefore, the findings on the prevalence of residual EDS and its association with CPAP therapy in Japan are probably similar to those of other countries.