<p>Although previous research has linked adolescents’ sleep problems to excessive smartphone use and associated anxiety about losing device access (nomophobia), there is limited understanding regarding how problematic smartphone use specifically contributes to sleep disturbances among adolescents. This cross-sectional study examined the mediating role of problematic smartphone use and nomophobia in the relationship between parent–child interactions and adolescent sleep problems. The parent–child relationship was measured using reliable and valid self-report questionnaires employing Likert scales, administered in Indonesian. Data were collected from 672 students aged 15–19 years across ten high schools in Yogyakarta, Malang, Jambi, Palembang, Aceh, Lombok, Palangkaraya, Balikpapan, Makassar, and Sumbawa. Path analysis was conducted using Amos 20 to evaluate indirect effects, defined as mediating relationships between variables. Results indicated a significant indirect effect of the father-child relationship on adolescent sleep problems through problematic smartphone use and nomophobia (<i>β</i> = −.033). However, the mother–child relationship showed no significant indirect effect (<i>β</i> =.016). Practical implications include promoting parental awareness about their role in adolescents’ technology use. Specific practical implications include developing family-based educational workshops emphasizing healthy smartphone habits, creating guidelines for parental mediation of smartphone use, and implementing school-based interventions targeting sleep hygiene among adolescents. Future research could employ longitudinal designs to determine causality, integrate objective sleep assessments like actigraphy, and consider contextual influences such as peer relationships and academic pressures.</p>