Background: Insomnia is a common concern among university students, especially in medical education. This study examined the prevalence of insomnia among undergraduate medical students and its association with attention control and screen time. Materials and Methods: A cross-sectional survey was conducted among 609 MBBS students (first to fourth year) at Burdwan Medical College, West Bengal, during August–September 2025. Data were collected using the Insomnia Severity Index (ISI) and the Attention Control Scale–Short Format (ATTC). Statistical analyses included ANOVA, t-tests, Pearson’s correlation and multiple linear regression analysis. Results: The mean ISI score was 6.2 ± 4.8. Overall, 34% of students experienced insomnia (27% sub threshold, 7% clinical), with severity increasing across academic years (p = 0.004). Hostel residents had a higher prevalence than day-scholars (9% vs. 4%, p = 0.03). No significant gender differences were observed. Attention control was highest in first-year students and lowest in third-year students. Insomnia was a significant predictor of lower attention control after adjusting for gender, year, and residence (β = –0.27, p < 0.001).Higher screen time showed a clear dose–response relationship with insomnia severity. Conclusion:  ISI was a significant predictor of lower attention control after adjusting for demographic variables. These findings suggest that addressing sleep disturbances may be crucial for preserving cognitive function in medical students.