Background: Adolescence is a period of significant psychological, physical, and social changes. During this time, adolescents face increasing responsibilities, such as making educational and career decisions, managing peer relationships, and becoming more independent from their families. These changes are often accompanied by mood fluctuations and altered sleep patterns. This study aimed to explore the relationships between bright- and dark-side hypomania, insomnia, and various dimensions of health-related quality of life (HRQOL), such as self-esteem, family and peer relationships, social acceptance, and autonomy. Methods: A total of 1475 participants in mid-adolescence (mean age: 13.4 years; range: 11–16 years; 48.8% males) completed a series of self-reported questionnaires covering sociodemographic information, hypomania, including dark and bright-side hypomania, insomnia, and HRQOL. Results: Compared to participants with no or dark-side hypomania, participants with bright-side hypomania reported better HRQOL. Bright-side hypomania was significantly associated with favorable relationships with parents and home, peer relationships, and the school environment and with less insomnia. In contrast, dark-side hypomania showed significant associations with lower scores for self-esteem, moods and emotional states, peer relationships, social acceptance, the school environment, and more insomnia. Conclusions: Among a larger sample of adolescents, bright- and dark-side hypomania were associated with a broad, though specific variety of aspects of HRQOL and insomnia. Given that standardized programs are available to improve insomnia and resilience as a proxy of psychological well-being, such interventions may have the potential to improve adolescents’ psychological well-being and sleep quality concomitantly.