Association between Circadian Rhythm-Disturbing Factors and Metabolic Syndrome in Korean Adults: Korea National Health and Nutrition Examination Survey (2016-2020).

Background: Circadian misalignment is associated with metabolic syndrome. This study aimed to examine the association between circadian rhythm-disturbing factors and metabolic syndrome.

Methods: We used data from the 7th and 8th Korea National Health and Nutrition Examination Survey conducted between 2016 and 2020, which surveyed 16,253 individuals. Circadian rhythm-disturbing factors were defined as follows: sleep duration outside the reference group (6-8 hours), irregular breakfast, shift work, and physical inactivity. The adjusted odds ratio (aOR) for metabolic syndrome was calculated based on the number of circadian rhythm-disturbing factors present in adults over the age of 19 years.

Results: Among a total of 16,253 participants (mean age 48.2±15 years), metabolic syndrome was found in 5,237 participants (29.3 %). The participants were classified into three categories based on the number of circadian rhythm-disturbing factors as follows: 2,627 (15.6%) did not have any factors, 6,406 (38.13%) had one factor, and 7,220 (46.3%) had two or more factors. Participants with a single circadian rhythm-disturbing factor were 21% more likely to have metabolic syndrome (aOR, 1.21; 95% confidence interval [CI], 1.08-1.36), and participants with two or more factors were 27% more likely to have metabolic syndrome (aOR, 1.27; 95% CI, 1.12-1.43).

Conclusion: Circadian rhythm-disturbing factors were significantly associated with the prevalence of metabolic syndrome in Korean adults. This finding has potential clinical implications for maintaining circadian rhythms by avoiding certain factors to prevent metabolic syndrome. Further studies are required to confirm these findings.