Individual morningness-eveningness differences explain the rhythmic variations of behavioral and biological patterns. Several studies have corroborated that morningness preference increases over adulthood and aging. Adolescents shift their time of day preferences from morningness to eveningness during puberty. The aims of this study were translate to Spanish the Morningness-Eveningness Scale for Children (MESC) and to analyze age and sex differences. A group of 600 adolescents (aged between 12 and 16 years) participated in the study. Psychometric analysis showed that reliability and factor structure were suitable and similar to previous studies. The results indicated a clear decrease of morningness as of 12 years. Boys were more morningness-oriented than girls in several items of the questionnaire. In view of the results, several educational implications are raised.

The creation and adaptation of scales or inventories assessing specific circadian typologies has been a predominant focus within the field of chronopsychology. The present study addressed the psychometric properties of two scales of morningness-eveningness: the Morningness Composite Scale (CS; Smith, Reilly, & Midkiff, 1989) and the Early/Late Preferences Scale (PS; Smith, Folkard, Schmieder, Parra, Spelten, & Almirall, 1993). Internal consistency and factor invariance of the CS and PS were analyzed in two samples: a group of 203 university students (age range = 19-30) and a group of 125 working adults (age range = 31-65). Results indicated satisfactory internal consistency for both full scales with each age group and confirmed the factor invariance across age for the two CS factors and one of the PS factors. A higher tendency in morningness on both scales was noted in the adult sample.

Accumulating evidence suggests that evening-type adolescents are exposed to a number of determinants that might have a negative impact on their health condition. Given that few studies have investigated the association between chronotype and quality of life measures in large samples of adolescents, the aim of this study was to assess the relationship between morningness-eveningness and health-related quality of life among 1600 adolescents (aged 12-16 years). Adolescents completed the Veçú et Santé Perçue de L'adolescent (VSP-A) and the Morningness-Eveningness Scale for Children (MESC). Girls and older adolescents reported worse health indicators and were more evening oriented. Evening-type adolescents obtained lower scores on vitality, physical and psychological well-being, body image, relations with parents, relations with teachers, school work and global health scale.