This study investigates the critical relationship between sleep deprivation and cognitive functioning in adolescents, with particular focus on learning and memory processes. Using a mixed-methods approach combining neuroimaging techniques, cognitive performance assessments, and self-reported sleep data, this research examined 187 adolescents aged 13-18 over a six-month period. Results demonstrate significant negative correlations between reduced sleep duration and decreased performance on both immediate and delayed memory tasks. Neuroimaging data revealed reduced hippocampal activation and compromised prefrontal cortex function during learning tasks in sleep-deprived subjects. A novel feature selection technique was applied to reduce the dimensionality of the collected neurobiological datasets, enabling more precise identification of the neural pathways most affected by sleep loss. The findings suggest a dose-dependent relationship between sleep quantity/quality and cognitive performance, with even moderate sleep restriction (6-7 hours) showing measurable effects on learning outcomes. This research highlights the urgent need for educational policy reform regarding school start times and provides evidence-based recommendations for sleep interventions to optimize adolescent cognitive functioning and academic performance.