Article ID: EJ26-0018
Social jetlag (SJL), the misalignment between biological and social time, has been linked to adverse metabolic outcomes. However, the effect of body mass index (BMI) on this association remains unclear, particularly in Asian populations. This cross-sectional study utilized data from the Taiwan Biobank, including 65,832 adults with complete information on sleep timing and metabolic parameters. SJL was calculated as the difference in mid-sleep time between workdays and free days and categorized as <2 or ≥2 h. Metabolic syndrome (MetS) was defined using standard clinical criteria. Multivariable logistic regression models were used to examine the association between SJL and MetS, with stepwise adjustment for sociodemographic, lifestyle, and clinical factors. Additional analyses stratified participants into BMI categories (<24, 24–26.9, ≥27 kg/m2). After full adjustment including BMI, SJL ≥2 h was not significantly associated with MetS (adjusted odds ratio = 1.05, 95% confidence interval: 0.98–1.12; p = 0.180). In BMI-stratified analyses, a significant association was observed only in the overweight group (BMI 24–26.9 kg/m2; adjusted odds ratio = 1.12, 95% confidence interval: 1.01–1.24; p = 0.035), but not in normal-weight or obese groups. An association between SJL and MetS was observed only in the overweight group, suggesting a BMI-dependent association between SJL and MetS. These findings highlight the importance of considering BMI when evaluating the association between SJL and MetS and indicate that the relationship between circadian misalignment and metabolic risk may vary across BMI categories.
