Adolescents in this study averaged over h of

Adolescents in this study averaged over 8h of sleep per night, which is similar to what has been obtained in other studies with this age group (Wolfson and Carskadon, 1998; Fuligni and Hardway, 2006) and is close to the number of hours recommended for adolescents (Wolfson and Carskadon, 1998). Yet, some participants attained as few as 4.5h of sleep on average. Interestingly, average sleep duration was not associated with white matter integrity. In addition, the effects of sleep variability on glucose assay development were not due to large differences in sleep duration on weekends versus weekdays or to variability in bedtime. This suggests that day-to-day variability in the duration of sleep within the week may be particularly detrimental for youth.
Conflict of interest
Authors’ note Support for this study was provided by the NICHD (R01HD057164-S, Fuligni), NSF (NSF 1023293, Telzer), and a University of California Institute for Mexico and the United States Dissertation Research Grant (Telzer).
Introduction Neuroimaging studies have focused on the exploration of emotional attention – that is attention toward or away from emotional stimuli (Corbetta and Shulman, 2002; Corbetta et al., 2008; Posner and Petersen, 1990; Vuilleumier and Huang, 2009). Emotional attention can be impaired in affective disorders and given that mid-adolescence is a core incidence phase for affective disorders (Paus et al., 2008), characterizing the development of emotional attention in adolescence is of high clinical relevance. Emotional attention can be divided into (1) the automatic impulse to attend toward emotionally salient stimuli, bottom-up emotional attention, and (2) the goal-directed, controlled attention toward emotional stimuli, top-down emotional attention (Corbetta and Shulman, 2002; Vuilleumier and Huang, 2009). Bottom-up and top-down systems are in line in tasks in which participants have to focus on the emotion. However, in tasks, in which the emotion is irrelevant, bottom-up and top-down-systems interfere. Here, the individual either gets distracted and turns her attention toward the emotional distractor (bottom-up attention) or successfully keeps it on the primary task (top-down attention) ignoring the distractor (Vuilleumier and Huang, 2009). In adults, the two types of emotional attention are represented by different neural networks: For top-down emotional attention a dorsal frontoparietal network is activated including the dorsolateral prefrontal cortex, the dorsal parietal cortex, and the anterior cingulate cortex (ACC). Bottom-up emotional attention is modulated by a ventral frontoparietal network including the occipitotemporal cortex, orbitofrontal cortex, and the amygdala (Corbetta et al., 2008; Iordan et al., 2013; Vuilleumier and Huang, 2009). In adolescence, more engaged bottom-up regions and less engaged top-down resources may result in an imbalance of both attention systems with prepotent bottom-up processing (Casey et al., 2008). Therefore, the inhibition of distracting emotional stimuli required in top-down emotional attention is challenging for adolescents. For example, in a classroom context the impulse to direct attention toward emotional stimuli, e.g. the attractive classmate passing by, has to be inhibited to direct attention in a top-down fashion on the primary task, e.g. on the current essay. If these challenging developmental tasks are not successfully managed, the risk of affective disorders might increase (Steinberg, 2005). Few behavioral studies have investigated adolescent development of emotional attention. Most studies assessed inhibition of the motor impulse toward distractor stimuli in emotional go-no-go tasks. Overall, greater age-related improvements from adolescence to adulthood were found for negative and positive compared to neutral no-go-stimuli (Tottenham et al., 2011). When investigated separately, both negative (Cohen-Gilbert and Thomas, 2013) and positive (Somerville et al., 2011) no-go stimuli led to an increased false alarm rate for adolescents in comparison to adults. Thus, adolescents seem to be specifically sensitive toward distracting emotional stimuli. This pattern is also evident in a task that assesses the attentional inhibition of a distracting emotional incongruent flanking stimulus presented together with the task-relevant stimulus: Adolescents had larger interference effects for negative distractors and overall lower accuracy than adults (Grose-Fifer et al., 2013). Taken together, ignoring task-irrelevant emotional distractor stimuli undergoes developmental changes during adolescence.