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The circadian rhythm is controlled by central and peripheral circadian clocks operating together. The brain’s suprachiasmatic nucleus is the central pacemaker for the circadian system and is controlled by light exposure [1]. However, in peripheral organs that are not exposed to daylight, food intake is an important marker of the time of day [2]. These circadian rhythms contribute to metabolic problems such as obesity and diabetes [2,3]. Studies have identified several determinants of circadian disruption: short sleep duration, nonstandard work schedules, and irregular dietary patterns [4].
In this issue, Lee et al. [5] used data from the Korea National Health and Nutrition Examination Survey (KNHANES) to define four principal circadian-disrupting factors (insufficient sleep, irregular meal timing, shift work, and physical inactivity) and assessed their combined effects on metabolic syndrome prevalence. Their analysis demonstrated that participants with one disrupting factor were 21% more likely to develop metabolic syndrome, whereas those with two or more factors were 27% more likely, compared with individuals without any disrupting behaviors.
Korean Journal of Family Medicine has reported on studies regarding short sleep, skipping breakfast, and shift work among individuals with obesity, diabetes, and metabolic syndrome [6-9]. However, insufficient studies have investigated the relationship between various circadian rhythm-disrupting lifestyle factors and metabolic syndromes. Therefore, integrated study on the relationship between multiple factors and metabolic syndrome is warranted to better understand how these factors can operate together to disrupt circadian rhythms.
Lee et al. [5] further reported that all identified disruptors, except shift work, were significantly and positively associated with metabolic syndrome risk. Intriguingly, night-shift work was more negatively associated with metabolic syndrome than other shift types. As the authors noted, a KNHANES-based investigation did not confirm an association between shift work and metabolic syndrome among men [10], likely because of the absence of detailed data regarding the consistency of work patterns and the frequency of schedule changes.
In addition to sleep duration, irregular eating, and shift work, the authors included physical activity as a circadian rhythm-disrupting factor. Studies have revealed a particularly pronounced association between circadian misalignment and obesity among older adults, urban residents, non-smokers, individuals with depression or comorbidities, and those with low physical activity [4]. Additional studies are warranted to identify novel circadian misalignment factors and evaluate their cumulative impact on metabolic syndrome risk.
This study suggests that the greater the number of circadian rhythm-disrupting factors, the higher the risk of metabolic syndromes. These findings reinforce the preventive value of lifestyle interventions—adequate sleep, regular meal patterns, and sufficient physical activity—in reducing the risk of metabolic diseases.
Article Information
Conflict of interest
Jungun Lee is an Associate Editor of the journal but was not in volved in the peer reviewer selection, evaluation, or decision process of this article. Except for that, no other potential conflicts of interest relevant to this article were reported.
Funding
None.
Data availability
Not applicable.
Author contribution
All the work was done by Jungun Lee.
References
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