Morningness-Eveningness Among German and Spanish Adolescents 12-18 Years

Individual differences in human biological rhythms and diurnal preference (morningness-eveningness) are often based on self-report scales. Here, we compare Spanish (N = 771) and German (N = 1,182) adolescents (12-18 years) using the Composite Scale of Morningness (CSM). A 3-factorial solution of the CSM was supported in both countries, morningness, activity planning, and alertness factors, and the last two factors were invariant across countries. Morningness decreased with age, and higher morningness was found in German pupils. Gender differences were not significant concerning the alertness factor but existed in the activity-planning factor with girls scoring higher, and in the morningness factor with boys scoring higher. Interactions suggest that the linear trend toward eveningness is less pronounced in Spanish adolescents, whereas German boys showed the steepest linear decline in their over time compared to German girls and to Spanish boys who showed a U-shaped tendency.