The relevance of morning affect, eveningness and distinctness in regard to the mental health of adolescents.

Previous studies conducted in adults indicated that the distinctness, that is, the subjective feeling of fluctuations in mood and activation - was associated with health to a greater extent than were morning affect and eveningness, but few studies have examined these relationships among adolescents. A sample of 342 Spanish adolescents (11-14 years; 44.7% girls) were assessed for morning affect, eveningness, distinctness, health-related quality of life, life satisfaction, depression symptoms, sleep habits, and self-reported academic performance. The results indicated that distinctness was associated with worse health indicators. Girls reported higher scores on distinctness and depressive symptoms whereas boys reported higher scores on morning affect, life satisfaction, physical well-being and psychological well-being. The interaction between distinctness and sex indicated that girls with greater distinctness reported greater depression, lower physical and psychological well-being, and less autonomy. The interaction between morning affect and sex indicated that girls with greater morning affect reported lower peer and social support. The results obtained in this study underline the influence of distinctness on daily functioning, especially in girls, and highlight how this characteristic is related to other aspects of health. These findings suggest that the subjective feeling of fluctuations in mood and activation during the day may have a greater impact on adolescents' quality of life than do morning affect and eveningness, highlighting the importance of considering the circadian component of distinctness when designing programs to improve adolescent health.