Background: Sleep deprivation is a growing mental health issue that is characterized by a lack of adequate sleep with fatigue and lethargy. It is an increasing concern for early adolescents as they have constant access to the internet and social media nowadays. This research aimed to identify the prevalence of sleep deprivation and its associated factors among early adolescents. Methods: A cross-sectional study was conducted on 329 early adolescents from selected schools in Kathmandu valley. The lottery method was used to select the study area and simple random was used for sample units. A semi-structured questionnaire and face-to-face interview were conducted as a data collection tool and technique. KOBO toolbox and SPSS 25.0 were used for data entry and analysis. Relevant descriptive statistics were computed for all variables and the association was computed using the Chi-square test. Results: Among 329 respondents, 60.2% had poor sleep quality, and 54.7% were dependent upon social media. Sleep quality and social media dependency were positively associated with the gender of the respondent, frequency of checking social media apps per day, use of social media before sleeping and after waking up, duration of social media usage before sleeping, academic performance, and interest in studying. Conclusions: This study showed a significant relationship between social media usage, poor sleep quality, and academic performance. It highlighted a critical need for awareness of sleep deprivation and the psychological effects of excessive social media usage on adolescents in Kathmandu valley.