Knowledge of the sleep beliefs among adolescents is relevant in order to promote primary prevention of unhealthy lifestyles related to sleep hygiene. In study 1, sleep beliefs among 11-16-years-old adolescents were explored according to gender, age, and chronotype. Adolescents completed the Sleep Beliefs Scale (SBS; Adan A, Fabbri M, Natale V, Pratt G. 2006. SBS and circadian typology. J Sleep Res. 15:125-132) and the Morningness-Eveningness Scale for Children (MESC; Carskadon MA, Vieira C, Acebo C. 1993. Association between puberty and delayed phase preference. Sleep. 16:258-262) during normal school schedule. Results indicated incorrect sleep beliefs among boys and evening-types. In study 2, the effect of a sleep education program on sleep beliefs was analyzed. Results showed an increase of mean scores and percentage of correct responses of SBS after a sleep education program, especially among evening-type adolescents.

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.