Morningness-Eveningness Stability Scale improved (MESSi) is an assessment tool that evaluates distinctness of daily changes as well as the person's propensity for morningness and eveningness. The aim of this study is to evaluate psychometric properties of the Turkish version of MESSi and associations of chronotypes and diurnal variations with personality, affect, sleep quality as well as validity of the scale in Turkish adolescents. The sample of this study consisted of 445 students between ages of 10-19. Participants filled in MESSi, Morningness/Eveningness Scale for Children, Composite Scale of Morningness, Personality Traits Scale (BIG-5), Positive and Negative Affect Scale (PANAS), Pittsburgh Sleep Quality Index (PSQI). Reliability analysis of the scale showed quite reliable internal consistency values. Confirmatory factor analysis (CFA) was used to test construct validity of three-factor model of MESSi. An acceptable model fit was demonstrated in CFA. There was a moderate and significant relationship between MA and DI subscale scores of MESSi. A moderate but negative correlation was found between MA and EV subscale scores of MESSi. MA and DI subscale scores of MESSi were found to be weakly correlated with conscientiousness, emotional stability, openness to experience and subscale scores of BIG-5, respectively. There was a positive correlation of positive affect subscale scores of PANAS with MA and DI subscale scores of MESSi. MA subscale scores of MESSi were found to be negatively correlated with scores of subjective sleep quality, latency, duration, disturbances, habitual sleep efficiency, daytime dysfunction, and global scores of PSQI. This study shows that Turkish version of MESSi is valid and reliable for use in adolescents. Three-factor MESSi provides an advantage over other chronotype scales in adolescence since it includes DI subscale as well as MA and EV subscales. Psychometric results were supported by other chronotype scales and clinical features such as sleep, affect, and personality.
Keywords: MESSi; circadian preference; eveningness; morningness; personality; sleep quality.