title: Morningness-eveningness and amplitude - development and validation of an improved composite scale to measure circadian preference and stability (MESSi).
abstract: Measuring morningness-eveningness is an important aspect of individual differences because it is associated with many aspects of personality and health. The present study outlines recent advancements in the field of measurement and proposes an improved assessment of morningness-eveningness, such as the measurement of circadian amplitude, updating and reflecting new item developments, addressing the clock time based measures, the morning-biased items and the aspect of uni versus multidimensionality. Four studies have been carried out in Germany to present a novel development (with a total sample of N = 1181). In study I, the exploratory factor analysis (EFA) revealed three dimensions, one of morningness, one of eveningness and one of amplitude/stability. Then, items were reduced to present a clearer factor structure by removing ambiguous items. In the second study, a shortened questionnaire was applied, with 15 items (5 per construct), but Confirmatory Factor Analysis (CFA) did not provide acceptable fit indices. Refining items were made in study III, which again showed a clearer factor structure in EFA, and subsequently, in study IV, the refined set of 15 items provided a good fit of a CFA. The final questionnaire was tested for validity by applying clock times, personality questions and alertness ratings. Thus, this newly developed questionnaire contains three distinct dimensions. To reflect the new content, the scale is labelled morningness-eveningness-stability-scale improved (MESSi).
authors.affiliation: a Institute of Natural Sciences, Geography & Technology , University of Education Heidelberg , Heidelberg , Germany.|d Department of Biology , University of Tuebingen , Tuebingen , Germany.|e LEAD Graduate School , & Research Network , Tuebingen , Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Randler
authors.affiliation: b Department of Individual Differences and Work, Faculty of Psychology , Complutense University of Madrid , Madrid , Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Díaz-Morales
authors.affiliation: a Institute of Natural Sciences, Geography & Technology , University of Education Heidelberg , Heidelberg , Germany.|d Department of Biology , University of Tuebingen , Tuebingen , Germany.
authors.forename: Arash
authors.initials: A
authors.lastname: Rahafar
authors.affiliation: c Institute of Psychology, University of Education Heidelberg , Heidelberg , Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmer
mesh_terms: D000204:Activity Cycles / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005858:Germany; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000379:methods; D012737:Sex Factors; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult
keywords: Amplitude; chronotype; circadian rhythm; composite scale; measurement