Impact of overnight work on lifestyle and cardiometabolic risk factors: a study on employee health in Korean

Overnight work is associated with cardiometabolic disorders. While circadian misalignment is a recognized mechanism, the roles of socioeconomic status, physical activity (PA), sedentary behavior (SB), and stress in shaping cardiometabolic risk factors (CRFs) in the context of overnight work remain unclear. We analyzed 604 participants (302 overnight, 302 day workers; one-to-one age- and sex-matching) from the Korea National Health and Nutrition Examination Survey (2018–2021). Variables included work schedules, PA, SB, stress, and CRFs such as hypertension, HbA1c, lipid profiles, and fasting glucose. Analyses used chi-square tests, t-tests, and multinomial logistic regression. Overnight workers reported shorter weekday sleep (6.4 vs. 6.8 h, p < 0.001), longer work hours (39.7 vs. 36.9, p < 0.05), and higher HbA1c (5.8 vs. 5.7, p < 0.05). Odds of HbA1c ≥ 6.5% were greater (OR = 2.79, p < 0.01). They were also more likely to hold lower-income, blue-collar jobs (p < 0.001). PA, SB, and stress showed no significant differences. Despite similar lifestyle behaviors, overnight work adversely affects glycemic control, suggesting circadian disruption as a central driver of metabolic risk. This paradox emphasizes the importance of biological alignment and the need for interventions targeting sleep and metabolic health in overnight workers.