The present study examined the role of sleep in daily affective stress recovery processes in adolescents. Eighty-nine American adolescents recorded their emotions and stress through daily surveys and sleep with Fitbit devices for two weeks. Results show that objectively measured sleep (sleep onset latency and sleep debt) moderated negative affective responses to previous-day stress, such that stress-related negative affect spillover effects became more pronounced as amount of sleep decreased. Total sleep time and sleep debt moderated cross-day positive affect "bounce-back" effects. With more sleep, morning positive affect on days following high stress tended to bounce back to the levels that were common following low stress days. Conversely, if sleep was short following high stress days, positive affect remained low the next morning. No evidence for subjective sleep quality as a moderator of spillover/bounce-back effects was found. This research suggests that sleep quantity could relate to overnight affective stress recovery.Adolescence is a developmental period that is notorious for insufficient sleep (Carskadon, 2011). Given the importance of sleep on virtually all aspects of emotional processing (Kahn, Sheppes, & Sadeh, 2013;Palmer & Alfano, 2017), it seems likely that sleep, either duration or quality, could play a part in emotional recovery from daily stress for adolescents. It is important to understand processes of stress recovery because stress is an inevitable aspect of life and the ability to "bounce back" (i.e., recover) from it has important implications for overall emotional well-being (Tugade & Fredrickson, 2004). Research on recovery from daily stressors has largely focused on negative affect spillover effects from one day to the next (Bolger & Zuckerman, 1995;Gunthert, Cohen, Butler, & Beck, 2007;Marco & Suls, 1993). However, few researchers have investigated daily-level processes that might relate to everyday fluctuations in stress recovery, such as sleep. In this study, we investigated the role of daily sleep on stress recovery among adolescents. Sleep in adolescentsA majority of adolescents do not receive enough sleep (National Sleep Foundation, 2014). Although sleep experts recommend that adolescents sleep for 8-10 h a night, about 70% of adolescents sleep less than 8 h a night, and a large proportion get substantially less than 8 h. Average sleep duration decreases from 8.4 h per night in sixth grade to 6.9 h in 12th grade (Hirshkowitz et al., 2015; Paruthi et al., 2016).To a large extent, inadequate sleep in teenagers can be attributed to a confluence of biological and social changes that delay