Sleep Duration and Health Outcomes by Sex in the KoGES Ansan Cohort: A Cross-Sectional Interaction Analysis

Objective: To test whether sex modifies the association between habitual sleep duration and health outcomes in middle-aged Korean adults.Methods: We analyzed cross-sectional data from 3,709 participants in the Ansan arm of the Korean Genome and Epidemiology Study Phase 2 (2003–2004). Sleep duration was calculated as a weighted 7-day average and categorized as short (<7 hr), reference (7 to <9 hr), or long (≥9 hr). Primary outcomes were body mass index, fasting plasma glucose, a fatigue-related symptom score, and forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ratio. The primary analysis tested the sleep category×sex interaction using 2-df likelihood-ratio tests adjusted for age, income, marital status, occupation, smoking, drinking, and exercise. Secondary outcomes were controlled using the Benjamini–Hochberg false discovery rate.Results: In the primary fully adjusted model, sleep duration×sex interactions were not significant for body mass index (p=0.930), fasting glucose (p=0.388), fatigue-related symptom score (p=0.104), or FEV1/FVC ratio (p=0.855). A complementary short-versus-reference 1-df interaction contrast was nominally significant for fatigue-related symptom score (p=0.047). In an explicitly post hoc age-stratified analysis, the fatigue-related symptom score interaction was concentrated among participants aged <50 years (p=0.001): short sleep was associated with higher adjusted fatigue-related symptom scores in women (+4.75 points; 95% confidence interval [CI], +2.33 to +7.16) but not in men (-0.50; 95% CI, -2.52 to +1.52).Conclusion: This analysis found no evidence of broad sex modification for cardiometabolic or pulmonary outcomes. The younger-adult fatigue-related symptom score signal should be considered hypothesis-generating pendingreplication with validated fatigue measures and longitudinal data. The fatigue-related symptom score used in this study was not a validated fatigue instrument, which limits the interpretability of the fatigue findings.