Association between weekend catch-up sleep and medical expenditure: a longitudinal analysis of the Korean Health Panel Survey

Insufficient sleep is increasingly recognized as a major public health concern associated with substantial clinical and economic burden. Although weekend catch-up sleep (WCUS)—the extension of sleep on weekends to compensate for weekday sleep restriction—is a common behavioral response and has been linked to psychological and cardiometabolic benefits, its economic implications remain unknown. This study examined whether WCUS is associated with lower medical expenditure among Korean adults. We analyzed data from 12,634 adults participating in the 2017–2018 Korea Health Panel Survey, a nationally representative longitudinal cohort. WCUS was calculated as the difference between weekend and weekday sleep duration and categorized as non-WCUS (≤ 0 h), short WCUS (≤ 1 h), medium WCUS (≤ 2 h), and long WCUS (> 2 h). The primary outcome was total medical expenditure in 2018, and outpatient, inpatient, and emergency department expenditures were assessed separately. Two-part models—logistic regression for any expenditure and generalized linear models with gamma distribution and log link for positive expenditures—were used to estimate adjusted mean expected expenditures, controlling for sociodemographic, behavioral, clinical, and baseline healthcare utilization variables and accounting for complex survey design. WCUS was strongly and inversely associated with total medical expenditure. Compared with non-WCUS, adjusted marginal reductions were − KRW 589,503 for short WCUS, −KRW 1,278,094 for medium WCUS, and − KRW 1,398,869 for long WCUS, demonstrating a clear dose–response gradient. Outpatient and inpatient expenditures declined steadily with increasing WCUS categories, whereas emergency department expenditures were lowest among individuals with medium WCUS. In analyses stratified by weekday sleep duration, cost reductions were greatest among adults with insufficient weekday sleep (≤ 7 h); medium and long WCUS produced large, statistically significant reductions, whereas short WCUS did not. Among those with sufficient weekday sleep (> 7 h), all WCUS categories were associated with significantly lower expenditures, though with smaller absolute reductions. WCUS was associated with substantially lower annual medical expenditure, with the largest benefits observed among individuals experiencing insufficient weekday sleep. These findings suggest that moderate weekend sleep extension may help offset the economic burden of chronic sleep restriction and represent a practical, low-cost behavioral strategy to reduce health care costs at the population level.