Indexed on: 28 Jul '16Published on: 28 Jul '16Published in: Sleep and Biological Rhythms
The purposes of this study were to investigate the validity and reliability of the Japanese version of Horne and Östberg’s Morningness-Eveningness Questionnaire (MEQ) and the characteristics of chronotype using other questionnaires and wrist actigraphy in healthy young subjects. The participants were 102 university student volunteers. The participants were instructed to continue normal life activities and habitual sleep-wake rhythms without extraordinary events for a study period of eight consecutive days, including 7 nights. Actual sleep-wake patterns were recorded by wrist actigraphy. The participants completed four questionnaires: MEQ, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Center for Epidemiologic Studies Depression Scale (CES-D). From the actigraphy data, sleep parameters such as bedtime, waketime, midtime, time in bed, sleep onset latency, wake episodes, wake after sleep onset, total sleep time, and sleep efficiency were derived. Cronbach’s α coefficient for internal consistency of the total MEQ score was 0.815, indicating high reliability. One-way analyses of variance showed that there were significant differences among the three chronotypes for bedtime, waketime, midtime, ESS, PSQI, and CES-D. Pearson’s correlation coefficients revealed that there were moderate negative correlations between MEQ scores and bedtime, waketime, and midtime, and that there were weak negative correlations between MEQ scores and ESS scores, PSQI scores, and CES-D scores. The results of this study demonstrated the validity and reliability of the Japanese version of the MEQ. In addition, the findings of this study showed that evening chronotypes were associated with greater daytime sleepiness, poorer sleep quality, and a depressive tendency.