Objective: To investigate the dynamic influence mechanism of the interaction between physical exercise and pre-sleep screen time on sleep quality among college students, so as to provide a theoretical basis for sleep health interventions in the population. Methods: From March to April 2025, a convenience sample of 2 075 students was recruited from eight universities in Jiangsu Province to participate in an online survey. Physical exercise was assessed using the Physical Activity Rating Scale-3 (PARS-3), sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI), and pre-sleep screen time behaviors were recorded using a self-designed structured questionnaire. Binary Logistic regression was used to examine the independent associations of physical activity level and pre-sleep screen time with sleep disorders. An interaction effect model was then applied to plot the dose-response relationship among the three variables. Results: The overall prevalence of sleep disorder among college students was 50.3%. Significant differences in the prevalence of sleep disorder were observed across groups of sex, academic discipline, grade, pre-sleep screen time, and physical exercise ( χ 2=42.45, 14.81, 18.99, 113.23, 40.61, all P <0.05). Binary Logistic regression showed that pre-sleep screen time was associated with the risk of sleep disorders (≤15 min: OR =1.70; 16- 30 min : OR =1.91; 31-60 min: OR =3.31; >60 min: OR =5.32), while both moderate ( OR =0.44) and high ( OR =0.57) physical exercise were associated with a reduced risk (all P <0.05). The interaction effect was statistically significant (Wald χ 2= 6.82 , P <0.01). The dose-response curves revealed that, in the low-exercise group, sleep quality deteriorated sharply with increasing screen time (the predicted mean dropped to 28% at the >60 min threshold, P <0.01); in the moderate exercise group, an inverted U-shaped trend was observed, with an optimal window of 16-30 min; and in the high exercise group, a significant buffering effect was found, with the predicted mean remaining at 43% even under >60 min screen exposure, representing a decrease of only 4% compared with the no-screen use group ( P >0.05). Conclusions High screen exposure combined with low physical exercise represents the primary behavioral pattern associated with a high prevalence of sleep disorders. Regular physical exercise can partially offset the negative effects of excessive screen time on sleep.