Chronobiological distribution and psychometric properties of the Morningness-Eveningness Questionnaire in a population from Ecuador close to zero latitude.

The Morningness-Eveningness Questionnaire developed by Horne and Östberg has long been used to assess chronotype preferences in people worldwide. However, many of the questionnaire's validations have been conducted in countries located at latitudes far from the equatorial line, rather than in regions where the light-dark cycle is more constant, such as Ecuador. Therefore, the aim of this study was to examine the chronobiological distribution and psychometric properties of the questionnaire in the city of Quito, Ecuador, a region situated close to latitude zero. To this end, a descriptive analysis of chronotype distribution was conducted on the full sample (N = 800), revealing that the majority of participants were classified as Intermediate (Neither Type) or Morning types. Furthermore, an Exploratory and Confirmatory Factor Analysis was performed, resulting in a reduction to three main factors: morningness (items 11, 15, 18 and 19), activation (items 2, 10, and 12), and bedtime preference (items 3, 4, 7, and 13). However, despite the robustness of the model, there were issues with internal consistency across factors, low convergent validity, and null test-retest reliability. Finally, the study discusses the importance of this type of research on chronobiological preferences in countries near latitude zero.