Reliability and Validity of the Korean Version of Morningness-Eveningness Questionnaire in Adults Aged 20–39 Years

Morningness-Eveningness (ME) can be defined by the difference in individual diurnal preference observed from general behavioral patterns including sleep habits. The Horne & Östberg Morningness-Eveningness Questionnaire (MEQ) has been used for classifying ME types. We examined the reliability of a Korean version of the MEQ (Korean MEQ) and verified its validity by comparing responses on the Korean MEQ to objectively-recorded sleep-wake rhythms. After translating and back translating the MEQ from English into Korean, we examined the internal consistency of 19 items of the Korean MEQ in 91 subjects, and the test–retest reliability in 21 subjects who took the Korean MEQ twice, four weeks apart. The Korean MEQ was then administered to 1,022 young adult subjects. A subset of 46 morning, neither, and evening type subjects took part in a validation study in which their rest-activity timing was collected by actigraphy for 7 days. Cosinor analyses on these data were done to obtain the acrophase and amplitude of the sleep-wake rhythm. Cronbach's alpha of the total scores from the Korean MEQ was 0.77, and the test-retest reliability intra-class correlation coefficient was 0.90 (p