Spontaneous brain activity in obstructive sleep apnea with excessive daytime sleepiness

<bold>Purpose:</bold> This study aimed to reveal the characteristics of brain function activity in obstructive sleep apnea (OSA) with excessive daytime sleepiness (EDS) by the fractional amplitude of low-frequency fluctuation (fALFF) to provide evidence of the neurobiological mechanism of EDS in OSA. <bold>Methods:</bold> EDS was assessed by the Epworth Sleepiness Scale (ESS) and the multiple sleep latency test (MSLT). Patients showed EDS whenever the ESS score was >11, and the MSLT score was <8 min. The absence of EDS was defined as having an ESS score of ≤11 and an MSLT score of ≥8 min. The study includes fifteen male patients with EDS and seven without EDS. Nineteen healthy controls (HC) were also recruited. <bold>Results:</bold> Compared to HC, EDS patients showed fALFF increased significantly in the right thalamus, left putamen, right cerebellum lobe_6, and the cerebellum lobe_8, but decreased in the left superior frontal gyrus, dorsolateral, bilateral middle frontal gyrus, and the right inferior parietal gyrus. No-EDS patients showed significantly increased fALFF in the bilateral cerebellum lobe_6 and decreased in the inferior frontal gyrus, opercular part. Compared with No-EDS patients, the fALFF increased in the right thalamus, the postcentral gyrus, and the right fusiform. The fALFF was reduced in the left anterior cingulate and paracingulate gyri in the EDS patients. <bold>Conclusions:</bold> These results indicate that the thalamus and anterior cingulate gyrus are crucial in regulating sleepiness, suggesting they may be a critical neural circuit controlling EDS, which provides new ideas to further explore the neurological mechanisms of EDS in OSA.