BACKGROUND: In the recent digital era, individuals with internet gaming disorder (IGD) have reported a much higher prevalence of poor sleep quality, perceived stress and suicidal behaviour. However, the underlying mechanisms for these psychological problems remain unknown. AIMS: The primary aims of this study were to explore the mediating role of sleep quality on the relationship between IGD and the health outcomes of perceived stress and suicidal behaviour and to assess the prevalence and risk factors for IGD among medical students. METHODS: A cross-sectional study enrolling 795 medical students from two medical colleges in a rural area of North India was conducted from April to May 2022. The study participants were chosen using a stratified random sampling approach. A self-administered questionnaire was used to collect data, including sociodemographic and personal information and gaming characteristics. The study also included the Gaming Disorder and Hazardous Gaming Scale, the Pittsburgh Sleep Quality Index, the Perceived Stress Scale-10 and the Suicide Behaviors Questionnaire-Revised to measure IGD, sleep quality, perceived stress and suicidal behaviour, respectively. Multiple logistic regression for the risk factors and Pearson's correlation test for the relationship between variables were used. Hayes' PROCESS macro for SPSS was employed to carry out mediation analysis. RESULTS: Among the 348 gamers with a mean age of 21.03 (SD 3.27) years, the prevalence of IGD was 15.23% (95% confidence interval: 11.6% to 19.4%). In the correlational analysis, small to large (r: 0.32-0.72) significant relationships between scores of IGD and other health outcomes were established. The indirect effect (B=0.300) via sleep quality accounted for 30.62% of the total effect (B=0.982) of IGD on perceived stress (partially mediated), while sleep quality (B=0.174) accounted for 27.93% of the total effect (B=0.623) of IGD on suicidal behaviour (partially mediated). The factors of being male, living in a single-parent family, using the internet for other than academic purposes (1-3 hours and more than 3 hours/day), playing games for more than 3 hours/day and playing games with violent content were associated with IGD symptoms. CONCLUSIONS: Using a dimensional measure, the results specified the relationship between IGD and perceived stress and suicidal behaviour by demonstrating that sleep quality meditated them. This modifiable mediating factor can be addressed by psychotherapy to mitigate the risk of perceived stress and suicidal behaviour among the future medical workforce.