The primary goals of this project are to examine the short and long-term effects of improving sleep as an important component of treating anxiety disorders in youth. These goals build upon four lines of evidence regarding sleep and emotion regulation in adolescence: 1) Developmental changes in sleep, circadian, and affective systems at puberty create increased vulnerabilities for both sleep and emotional problems (and their interactions) in ways that lead to high rates of sleep difficulties in adolescence. 2) Youth with Generalized Anxiety Disorder are particularly prone to sleep problems because of increased vigilance and inclinations to worry and ruminate at bedtime; 3) Sleep loss can interfere with affect regulation and distress tolerance, and thus, sleep difficulties create added burdens in the domains of affective and social functioning. 4) Insomnia and chronic sleep disturbance are significant risk factors for the development of depression and other adverse health outcomes. Taken together, these four lines of evidence raise compelling questions regarding the opportunities for early intervention to improve and enhance sleep in youth with anxiety. Project 2 addresses these questions by: (a) assessing sleep changes during CBT for anxiety to examine whether sleep improvements may partially mediate some positive effects of CBT; (b) offering a six-week sleep intervention to those children who continue to show sleep difficulties after CBT (c) testing this sleep intervention by randomizing 2/3 to receive the multi-component sleep intervention and 1/3 to receive a comparison supportive treatment; and (d) assessing whether improving sleep will further enhance affective, clinical, and social functioning. This project addresses a set of issues of considerable clinical relevance in treating anxiety disorders. It also examines early adolescence as a key time in development for sleep intervention in ways that could inform a prevention strategy for depression. More generally, this project addresses issues of great concern to public health and social policy regarding the consequences of insufficient sleep in youthnot only its effects on cognitive, emotional, behavioral, and academic function, but also a broader range of health problems where sleep has been implicated, including the development of affective disorders, alcohol, nicotine, and other substance use, accidents, and obesity and metabolic syndrome.