Objective: Social jetlag, ie, the mismatch between biological and social timing, has been suggested to induce obesity and cardiometabolic abnormalities. Yet, no study has currently linked social jetlag to metabolic syndrome (MetS) among Asians. The aim of this study was to investigate the cross-sectional association of social jetlag with MetS in a Japanese working population.
Methods: Participants were 1164 employees, aged 18-78 years, who completed a health survey at a periodic checkup. Social jetlag was calculated as the difference in hours of midpoint of sleep times between weekdays and weekends. MetS was defined according to the Joint Interim Statement criteria. Multivariable logistic regression was used to examine the association between social jetlag and MetS with adjustment for potential confounding variables.
Results: Greater social jetlag was significantly associated with an increased likelihood of having MetS. The multivariable adjusted odds ratio (95% confidence intervals) for ≥2 h of social jetlag was 1.92 (1.01-3.67) compared to those with <1 h of social jetlag. Of the components of MetS, greater social jetlag was significantly associated with an increased likelihood of having high waist circumference; the multivariable adjusted odds ratio (95% confidence intervals) for ≥2 h of social jetlag was 2.26 (1.33-3.84) compared to those with <1 h of social jetlag.
Conclusion: Social jetlag may be associated with an increased likelihood of having MetS among non-shift workers.
Keywords: Japanese; Metabolic syndrome; Sleep onset time; Social jetlag; Wake-up time.
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