ORIGINAL ARTICLE Anxiety during adolescence: considering morningness– eveningness as a risk factor Juan F. Dı ´az-Morales 1 Received: 25 February 2015 / Accepted: 11 August 2015 Ó Japanese Society of Sleep Research 2015 Abstract Evening preference has recently been identified as a risk factor for depression and anxiety. In this study, the relationship between anxiety, morningness–eveningness and sleep habits were examined during adolescence. Adolescents aged 12–16 years (n = 1406; 50.9 % girls) completed the Morningness–Eveningness Scale for Chil- dren, the State-Trait Anxiety Inventory and open questions pertaining to their typical bedtime and rising time during weekdays and weekends. Anxiety was associated with age, eveningness, early risetime and shorter time in bed during weekdays. No significant correlations were found between anxiety, risetime and bedtime on the weekend, time in bed on the weekend and social jetlag. A greater proportion of evening types was found in the high anxiety group. With regard to sex, girls reported higher anxiety levels, an earlier risetime and bedtime during the weekdays, a later risetime on weekend, a greater time in bed during weekend and higher social jetlag. Keywords Adolescents Á Morningness–eveningness Á Anxiety Introduction Trait anxiety has been described as a stable susceptibility or a proneness to frequently experience the state of anxiety [1, 2]. Low level of trait anxiety has been associated with positive well-being and mental health [3]. Adolescence is a particularly salient stage of life for the development of anxiety. The median age of onset for anxiety symptoms is estimated to be approximately 11 years of age [4]. Young adolescents not only experience considerable physical, psychological, and social developmental changes, but they also face ecological challenges, such as the transition from elementary to middle school, exposure to unfamiliar peers, more teacher-imposed control and discipline, less personal student–teacher relationships, emphasis on social compar- ison, and dissolution of social networks [5]. This transition period encompasses both developmental and contextual changes that, together, can be stressful to many adolescents. Morningness–Eveningness (M–E) is the most widely studied characteristic of human circadian function. It reflects individual differences in the circadian phase posi- tion of biological rhythms and is frequently evaluated by asking preferred hours for optimal activity. During the lifespan, first, there is a shift towards eveningness during the age of puberty, and second, a shift back towards morningness, which could be viewed as a biological mar- ker of the end of adolescence [6]. After reaching adoles- cence, most people gradually become more and more morning-type. The shift to eveningness occurs around the age of 12–13 years, which has widely been described in various countries and, consequently, it has been considered that this change is based on biological changes that occur throughout puberty [7]. However, although maturational changes exert an influence on the shift towards eveningness during adolescence, such a shift is also affected by several factors, including environmental (e.g., natural and/or screen light exposure), social (e.g., social life and school schedules), physiological (e.g., physical activity and meal timing), and psychological (e.g., parental discipline regarding sleep habits) [8]. Compelling evidence suggests & Juan F. Dı ´az-Morales juanfcodiaz@psi.ucm.es 1 Faculty of Psychology, Complutense University of Madrid, Campus de Somosaguas, s/n, 28223 Madrid, Spain 123 Sleep Biol. Rhythms DOI 10.1007/s41105-015-0032-8