LAUSR

Abstract In this study, the day-of-week effect on positive and negative affect, taking into account the moderating effect of chronotype, sleep length and sex, was analyzed. Ninety-four adolescents (16.1 ± 1.24 years old) attending high schools in the morning filled out diaries to assess the natural day-to-day fluctuations in mood and sleep. Using multilevel modeling, the results indicated that positive affect increased and negative affect decreased over the weekend. Negative affect was moderated by chronotype such that negative affect decreased less over the weekend in evening adolescents. Short sleep length was related to negative affect, and girls reported higher negative affect. Individual differences in weekly mood patterns should be taken into account when designing psychosocial interventions for adolescents.