Purpose <p>Sleep and psychological disorders are critical global health issues, and medical personnel are not immune to their effects. This cross-sectional study explores the relationship between Dysfunctional Beliefs and Attitudes about Sleep (DBAS) and mental health among medical staff, with a focus on the mediating role of sleep quality.</p> Methods <p>A web-based questionnaire was distributed to participants between April and May 2023.The research employed several assessment tools, including a General Information Questionnaire, the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS), the Pittsburgh Sleep Quality Index (PSQI), the Patient Health Questionnaire (PHQ-9), and the Generalized Anxiety Disorder Scale (GAD-7).</p> Results <p>The study included 263 medical staff and 270 non-medical staff. Medical personnel reported significantly higher DBAS scores and poorer sleep quality than non-medical staff (p &lt; 0.01). There were significant correlations between DBAS, sleep quality (r = -0.232, p &lt; 0.01), and symptoms of depression (r = -0.242, p &lt; 0.01) and anxiety (r = -0.274, p &lt; 0.01) among medical staff. Further analysis of the intermediary effect revealed that sleep quality partially mediated the relationship between DBAS and symptoms of depression and anxiety.</p> Conclusion <p>The findings suggest that depression and anxiety can adversely impact beliefs and attitudes about sleep, potentially leading to poorer sleep quality. Conversely, cultivating positive beliefs and attitudes about sleep may act as cognitive protective factors, promoting better sleep quality and mental health, particularly among medical professionals.</p>