<p>Adolescence is a crucial stage for the rapid development of sleep patterns and emotional regulation abilities. Although previous studies have indicated an association between sleep quality and expressive suppression, the bidirectional mechanisms of these associations over time and their gender differences remain unclear. This study conducts a three-wave longitudinal study with Chinese adolescents as the sample, aiming to explore the two-way dynamic relationship between sleep quality and expressive suppression, as well as gender differences. Each wave is spaced six months apart, and after matching, 1,235 participants who provided valid responses in all three waves—all of whom were adolescents aged 14 to 19 (<i>M</i>_age = 16.42, <i>SD</i> = 0.81; 56.8% girls)—were included. The results showed that the association between adolescents’ sleep quality and expressive suppression presented a dynamic influence relationship from unidirectional prediction (T1→T2) to mutual prediction (T2→T3). Multigroup analysis revealed that this dynamic relationship was more significant and stable in girls, while no significant and consistent bidirectional effect was shown in boys. These findings suggest that in collectivistic cultures, sleep quality is an important antecedent influencing adolescents’ use of expressive suppression. However, over time, sleep quality and expressive suppression show a reciprocal influence. The different development patterns of the reciprocal influence between sleep quality and expressive suppression in boys and girls suggest that it is crucial to consider the influence of sex in studies explaining how sleep affects emotional regulation.</p>