Initial psychometric characterization for the Portuguese version of the Morningness-Eveningness-Stability-Scale improved (MESSi).

This work reports the initial psychometric characterization of the Morningness-Eveningness-Stability-Scale improved (MESSi) for Portuguese young-adults (N = 466). A confirmatory factor analysis confirmed a three-factor model (i.e. Morning Affect, Eveningness and Distinctness) in our data, as originally proposed. Furthermore, construct validity evidence in relation to external variables (i.e. morningness/eveningness and satisfaction with life), as well as adequate reliability (i.e. internal consistency and test-retest reliability), were found. Finally, sex-based invariance and between-sex differences were investigated for the three subscales, as were correlations with age. Results point to the suitability of the MESSi for multi-cultural research on relevant and multiple aspects of chronotype.