title: Circadian preferences in young adults: Psychometric properties and factor structure of the Portuguese version of the Preferences Scale (PS-6).
abstract: Morningness is a trait-like variable which has been extensively studied within chronobiology. Despite the number of existing measures to assess morningness, there is a need for brief instruments that are psychometrically sound to be used in applied settings. Accordingly, the modified version of the Preferences Scale (PS-6) comprises six items and was reported to have adequate reliability and satisfactory validity indicators. In this article, the psychometric properties of the Portuguese version of the PS-6 are reported. A total of 700 students attending medical school were recruited, and this sample was randomly divided into two groups. In the first group (n = 352), we assessed the internal consistency calculations and conducted a principal component analysis of the posited structure. In the second group (n = 348), we conducted a confirmatory factor analysis (CFA) using structural equation modeling. Overall, the results indicated that the PS-6 has adequate reliability (α = .75) and is constituted by two components: (I) preferred cognitive activities timings and (II) preferred sleeping-eating timings, respectively. In conclusion, the Portuguese version of the PS seems suitable for use in research and applied settings such as shift work schedules management. However, the applicability of the PS-6 in other samples and further validity indicators should be both investigated. The use of actigraphy and biological measures should also be collected to enhance the robustness of the PS-6.
authors.affiliation: a University of Aveiro , Department of Education and Psychology , Aveiro , Portugal.|b Universidade de Coimbra Faculdade de Medicina , IBILI - Institute for Biomedical Imaging and Life Sciences , Coimbra , Portugal.
authors.forename: Daniel Ruivo
authors.initials: DR
authors.lastname: Marques
authors.affiliation: c University of Aveiro , Coimbra , Portugal.
authors.forename: Ana Allen
authors.initials: AA
authors.lastname: Gomes
authors.affiliation: d Central Queensland University, School of Business and Law , Rockhampton , Australia.
authors.forename: Lee
authors.initials: L
authors.lastname: Di Milia
authors.affiliation: e Faculty of Medicine, University of Coimbra , Coimbra , Portugal.
authors.forename: Maria Helena Pinto de
authors.initials: MH
authors.lastname: Azevedo
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D010555:Personality Inventory / Q000706:statistics & numerical data*; D025341:Principal Component Analysis; D011594:Psychometrics / Q000379:methods; D015203:Reproducibility of Results; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Circadian preferences; eveningness; morningness; psychometrics; scale