© 2018 Elsevier Ltd Purpose: To examine longitudinal associations between five commonly used technology devices prior to bedtime and real-life academic outcomes in adolescents. Methods: A total of 853 adolescents were recruited to a three-year prospective cohort study, with annual assessments. Academic grades/levels for three core subjects (English, Mathematics, and Science) were extracted from school records, and standardized (z-scores) were derived at the end of each academic year. A validated questionnaire was used to determine the frequency of using five types of technology (television viewing, video gaming, mobile telephone use, listening to music, and social networking) before bedtime. Results: After adjustment, English attainment was the subject most affected by prebedtime technology use, where three of five technologies assessed were negatively and prospectively associated (social networking [β = −.07 and p =.024], video gaming [β = −.10 and p =.008], and mobile telephone [β = −.07 and p=.017]). Social networking (β = −.07and p =.042), television viewing (β = −.08 and p =.044), and mobile telephones (β = −.07 and p =.031) were associated with significant impairment in English for girls whereas attainment in boys was most impaired by video gaming (β = −.12 and p =.014). Conclusions: The use of electronic devices by adolescents before bedtime may reduce their academic attainment, but apart from video gaming for boys, the negative impact of near bedtime technology use on academic performance is small.