Factor structure of the Brazilian version of the Morningness-Eveningness Scale for Children (MESC) for chronotype assessment in adolescents.

To translate and adapt the Morningness-Eveningness Scale for Children into Brazilian Portuguese, translation, back-translation, technical review, expert evaluation, focus group, test-retest, and factorial structure of the instrument were performed. The total sample consisted of 676 students from the 6th to 9th grade of elementary school and from the 1st to 3rd year of high school, aged between 10 and 19 years, 343 girls (51%) and 333 boys (49%), with a mean age of 13.98 (2.00) years. Of these, 40 students from the 6th grade, aged between 10 and 13 years, participated in the test-retest, 24 girls (60%) and 16 boys (40%), with a mean age of 11.17 (0.50) years. Descriptive and inferential analyses were performed, including exploratory and confirmatory factor analyses. High levels of internal consistency (α = 0.742) and test-retest (0.974) were obtained, in addition to high values for clarity of language (0.88), practical relevance (1.00) and theoretical relevance (1.00). In the confirmatory factor analysis, the model presented satisfactory validity indices: χ2 = 40.811 (df = 34), p = 0.196, RMSEA = 0.025 (90% CI: <0.001-0.049), CFI = 0.990 and TLI = 0.987, with no need for adjustments between the covariances between the items. Therefore, the MESC-BR was considered an adequate instrument to assess circadian preferences in Brazilian adolescents, given its test-retest psychometric properties and construct validity.