Examination of Oral Functions Related to Excessive Daytime Sleepiness

Excessive daytime sleepiness (EDS) is a major occupational health concern that negatively affects worker safety, productivity, and overall health. Possible associations between oral function and EDS have been reported. This study aimed to investigate the relationships between lip-seal force, tongue pressure, and questionnaire-based assessments of oral function and EDS in a working-age population. A cross-sectional study was conducted with 392 Japanese male workers. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS), and swallowing function was evaluated using the Eating Assessment Tool-10 (EAT-10). Participants were classified into two categories based on ESS scores: a severe EDS group (ESS ≥11) and a moderate-to-severe EDS group (ESS ≥5). Additional variables included body mass index (BMI), self-reported snoring, tongue pressure, and lip-seal strength. To identify factors independently associated with higher ESS scores, we performed multivariate logistic regression analyses. Participants with ESS scores ≥11 were classified as having severe EDS, while those with scores ≥5 were categorized as having moderate or severe EDS. In the severe EDS group, EAT-10 scores and snoring were significantly associated with ESS. In the moderate or severe EDS group, significant associations were found between ESS scores and EAT-10, snoring, and lip-seal strength. No significant associations were observed between ESS scores and tongue pressure or BMI. The findings show that dysphagia and reduced lip-seal strength are significantly associated with EDS among working-age Japanese men. Oral function assessments may be a useful tool for early detection and prevention of sleep-related disorders in occupational health settings.