Background: Sleep is a complex phenomenon that plays a pivotal role in ensuring the optimal functioning of the body, especially in adolescence. Poor-quality sleep among adolescents is a major public health problem and the subject of numerous studies in other parts of the world; however, it remains relatively underexplored in our context. This study aimed to assess sleep quality among adolescents attending schools in urban and semi-urban areas. Methods: This descriptive and analytical cross-sectional study was conducted over seven months. We included all voluntary adolescents aged 10–19 years who had given their written informed consent or that of their legal guardian(s). Our sampling was convenient and consecutive. Data on socio-demographic features and lifestyle were collected, and we used the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Hospital Anxiety and Depression Scale to assess each participant. Univariate and multivariate analyses were performed to identify factors associated with sleep quality. P < 0.05 was considered statistically significant. Results: A total of 952 were selected, including 309 in semi-urban areas and 643 in urban areas. The mean age of the population was 16.33 ± 1.70 years, with 52.0% female participation. Drug consumption was found in 25.3% of participants, and psychoactive substance consumption in 49.9% of participants, with the rates of consumption of these substances being significantly higher in urban areas than in semi-urban areas. Sleep quality was poor in 41.0% of students, 46.3% in urban areas, and 29.3% in semi-urban areas, the prevalence of sleep quality being significantly higher in urban areas (p < 0.001). Insomnia, which was identified in 19.4% of study participants, was the most common sleep disorder in our study population. Independent risk factors for poor sleep quality among students included living in urban areas, age between 17 and 19 years, the female sex, being in the first or last year of school,