Psychological Distress, Daytime Sleepiness, Fatigue, and Health-Related Quality of Life in Young Adults: A Cross-Sectional Study with Implications for Rehabilitation

Background/Objectives: This study examined associations between psychological distress, daytime sleepiness, mental and physical fatigue, and HRQoL in young adults and identified key predictors relevant for rehabilitation-oriented screening and intervention. Methods: In this cross-sectional analytical study, 371 university students (18–25 years) completed the Epworth Sleepiness Scale, Depression Anxiety Stress Scales-21, Fatigue Assessment Scale, and 12-Item Short Form Health Survey. Descriptive statistics, one-way ANOVA, multivariate general linear models, multiple linear regression, and logistic regression were applied to evaluate associations with fatigue and SF-12 physical and mental health scores and categories. Results: Most participants reported mild–moderate distress and fatigue, and about half of the participants had SF-12 scores below the sample median. Severe mental and physical fatigue were associated with substantially higher stress, anxiety, and depression than normal fatigue (all p < 0.001). Psychological variables explained 52% of the variance in mental fatigue and 30% in physical fatigue, with lower R2 for SF-12 physical (0.17) and mental health (0.29). Depression and stress were the strongest predictors of mental fatigue and low SF-12 mental health scores, whereas anxiety was more closely related to physical fatigue and physical health. Sleepiness showed weak, inconsistent associations after adjustment. Higher distress categories significantly increased the odds of HRQoL below the sample median. Conclusions: Psychological distress, particularly depression and stress, was strongly associated with fatigue and was also associated with poorer health-related quality of life, although the adjusted models indicated a more modest contribution to HRQoL. The findings support the value of considering psychological distress in rehabilitation-oriented screening while recognizing that HRQoL is influenced by multiple factors.