​This study examines how a school-based sleep intervention improves sleep and well-being in children and adolescents. Building on Gentofte Municipality's existing school-based sleep program for adolescents, we will expand the model to younger children (from 5th grade) and to municipalities with broader socioeconomic diversity (Gladsaxe, Rødovre). The study includes: (A) screening and detailed assessment of sleep, cognitive, and psychosocial functioning before and after sleep education; (B) qualitative interviews exploring barriers to healthy sleep habits; and (C) planning of a randomized controlled trial testing a school-based CBT-I intervention for adolescents with persistent sleep-wake distrubances. The goal is to create effective, lasting strategies for improved sleep habits.