Sleep Quality and Mental Health Among Medical Students: A Cross-Sectional Study

<b>Background:</b> Sleep disturbances and mental health disorders represent a significant public health concern. Medical students, in particular, experience intense academic pressure, long study hours, irregular schedules, and the emotional burden of clinical training, all of which may contribute to the development of sleep disturbances and mental health issues. This study aims to assess sleep quality and the prevalence of symptoms of depression, anxiety, and stress among medical students, as well as their interrelationships. <b>Methods:</b> This multicentric cross-sectional study was conducted in January and February 2025 among medical students from two medical faculties in Croatia. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), while symptoms of depression, anxiety, and stress were evaluated using Depression, Anxiety, and Stress Scale-21 (DASS-21). <b>Results:</b> The study included 386 participants, of whom 96 were male and 290 were female students. It was found that 67.9% of students had poor sleep quality, while symptoms of depression, anxiety, and stress were reported by 38.8%, 45.3%, and 40.4% of participants, respectively. Female students exhibited higher PSQI scores (U = 10,205, <i>p</i> < 0.001), as well as higher levels of depression (U = 10,372, <i>p</i> < 0.001), anxiety (U = 10,328, <i>p</i> < 0.001), and stress scores (U = 10,560, <i>p</i> < 0.001). Additionally, significant moderate positive correlations were observed between the total PSQI score and depression (ρ = 0.566, <i>p</i> < 0.001), anxiety (ρ = 0.489, <i>p</i> < 0.001), and stress scores (ρ = 0.503, <i>p</i> < 0.001). Moreover, an increase in depression (β = 0.178, <i>p</i> < 0.001) and anxiety scores (β = 0.141, <i>p</i> < 0.001) contributed to a higher total PSQI score, indicating poorer sleep quality. <b>Conclusions:</b> A high prevalence of poor sleep quality and symptoms of depression, anxiety, and stress was observed among medical students, with female students exhibiting higher levels of these variables. Furthermore, poorer sleep quality was associated with higher levels of depression, anxiety, and stress.