Psychometric properties of the Morningness/Eveningness scale for children among Uruguayan adolescents: the role of school start times

Morningness/Eveningness (M/E) is an attribute related to adolescent mental and physical health. The Morningness/Eveningness Scale for Children (MESC) is a widely used instrument for measuring M/E in adolescents. In this study, an Spanish translation of the MESC was adapted to the Río de la Plata population. A psychometric study was carried out in a sample of 368 Uruguayan adolescents (63.6% females), between 15 and 18 years old, who attended to either a morning (7:30 AM to 11:30 AM) or an afternoon school shift (11:30 AM to 3:30 PM). The scale showed good reliability (Cronbach’s alpha = 0.74), high temporal stability (r = 0.86, p < 0.001), good concurrent validity with mid-sleep point (r = −0.42, p < 0.001), and a two-factor solution. No difference in scores was observed between sexes or age groups. However, scores were different between school shifts, which proved to be a useful tool to study social influences on the circadian preferences. This study shows that MESC is a reliable and valid instrument for M/E assessment in adolescents, but social pressures should be considered when employing this score.