This study examined the relationships among smartphone use, sleep duration, academic stress, and self-reported focus and memory among high school students. A total of 100 students (ages 13–22; M = 16.4 years) completed an anonymous online survey assessing daily phone screen time, frequency of phone checking during study sessions, sleep habits, perceived academic pressure, and cognitive outcomes including concentration, retention, and task-switching ability. Descriptive and comparative analyses revealed that students using their phones for more than six hours per day reported substantially greater difficulty maintaining focus, higher rates of notification-related distraction, and lower confidence in academic retention. Students sleeping fewer than six hours per night demonstrated elevated procrastination tendencies and impaired stress management. Multilingual students reported slightly stronger perceived cognitive flexibility. Findings suggest that chronic smartphone exposure and sleep insufficiency represent compounding risk factors for academic burnout in adolescent learners. These results have implications for school-based digital wellness programs and parental guidance frameworks. Future research should incorporate longitudinal designs and objective measures of attention to validate self-report findings.