Social jetlag, sleep, and metabolic syndrome in adults: insights of circadian misalignment from NHANES 2017-2020

Metabolic syndrome consists of a set of interrelated metabolic dysfunctions and has been associated with sleep factors such as irregular schedules and social jetlag. This study evaluates the association between social jetlag and metabolic syndrome in adults and investigates whether this relationship varies according to sleep duration. Cross-sectional study with data from 4,438 adults from the 2017–2020 National Health and Nutrition Examination Survey (NHANES). Metabolic syndrome was defined according to international criteria. Social jetlag was calculated as the difference between the midpoints of sleep on weekdays and days off (adjusted for excess sleep time on weekends). Sleep duration was categorized as short, normal, and long. Logistic regression models adjusted for covariates selected based on a directed acyclic graph were used. Stratified analyses by sleep duration, formal interaction tests, and multinomial analysis were also conducted to assess the association between social jetlag and the number of components of metabolic syndrome. The prevalence of metabolic syndrome was 49.2%, while 14.2% of participants had social jetlag greater than one hour. In the overall analysis, no statistically significant association was observed between social jetlag and metabolic syndrome (OR = 1.09; 95% CI: 0.82–1.47). In the analysis stratified by sleep duration, among individuals with normal sleep duration, social jetlag >1h was associated with a higher chance of metabolic syndrome (OR = 1.70; 95% CI: 1.14–2.54). The interaction test indicated a modification of effect by sleep duration, with a significant result only in the normal sleep stratum (OR = 1.66; 95% CI: 1.12–2.44), reinforcing the findings of the stratified analysis. In addition, a dose-response gradient trend was observed: participants with social jetlag >1h were more likely to have 1–3 components (OR = 2.48; 95% CI: 1.28–4.80) and 4–5 components (OR = 4.86; 95% CI: 2.21–10.7) of metabolic syndrome, compared to those without any components. Social jetlag was associated with a higher chance of metabolic syndrome among adults with normal sleep duration, suggesting that the effects of circadian misalignment may vary according to sleep profile. Simultaneous consideration of sleep duration and regularity may be relevant for identifying more vulnerable groups and developing strategies to prevent metabolic outcomes.