Eveningness Chronotype is Associated with Sleep Disturbances and Depressive Mood in Korean Working Adults

Abstract

Objective: The aim of this study was to identify chronotypes and their associations with health problems among Korean working adults.

Background: Chronotypes and social jet-lag can affect the quality of sleep and health of workers. However, little is known about the distribution of chronotypes of Korean workers and the relationship between chronotypes and other health problems including sleep disturbance.

Design/Methods: A total of 1397 participants who visited a tertiary hospital for medical check-up between January and April 2016 were enrolled. Among them, we excluded the following patients from this study: 177 patients who did not complete the questionnaire; 243 patients who did not have job; 87 shift workers. Subjects completed the self-reported questionnaires with demographic factors, health/medical history, sleep-related scales including the Korean versions of the Morningness-Eveningness Questionnaire (MEQ), Insomnia Severity Index (K-ISI), Epworth Sleepiness Scale (K-ESS), and Global Sleep Assessment Questionnaire (GSAQ). Associations of chronotype with sleep-related scales, underlying disease, and medical check-up results were analyzed.

Results: Among 890 participants aged 25–76 (mean 52.22 ±8.79) years, 572 (64.3%) were men. Chronotype was classified as morning in 33.5% of subjects, evening in 5.7%, neither morning nor evening in 60.8%. Evening-type, when compared with morning type, was significantly associated with short sleep duration (≤ 6 hr, p = 0.009) and low sleep efficiency (p = 0.043). And the mean score of the ESS and ISI was significantly higher in evening-type (p < 0.001). A significant negative correlation was found between the scores of MEQ and ISI, and between scores of MEQ and ESS, demonstrating that the greater the eveningness, the worse the insomnia symptom and the more the excessive daytime sleepiness (ESS: r=−0.153, p<0.001, ISI: r=−0.196, p<0.001). Depressive mood from GSAQ was associated with evening-type (p< 0.001).

Conclusions: Evening-type was associated with sleep disturbance and depressive mood.

Disclosure: Dr. MOON has nothing to disclose. Dr. Lee has nothing to disclose. Dr. Cho has nothing to disclose.