Background <p>Medical residency is a demanding phase that often compromises sleep quality and mental health. This study aimed to assess the association between lifestyle factors—specifically smoking, caffeinated beverage intake, alcohol consumption, and body mass index—with sleep quality, anxiety symptoms, and depressive symptoms among medical residents in Syria.</p> Methods <p>This manuscript reports a secondary analysis of the dataset collected and described by Soqia et al. This multicenter cross-sectional study was conducted across 22 hospitals in Syria, enrolling 2,047 medical residents. Validated instruments were used to assess outcomes: the Pittsburgh Sleep Quality Index for sleep quality, the Patient Health Questionnaire-9 for depressive symptoms, and the Generalized Anxiety Disorder-7 scale for anxiety symptoms. Logistic regression analyses were conducted to investigate the relationships between lifestyle habits and mental health outcomes.</p> Results <p>Smoking was significantly associated with poor sleep quality (odds ratio 1.33), depressive symptoms (odds ratio 1.36), and anxiety symptoms (odds ratio 1.26). Among female residents, coffee and alcohol consumption were linked to increased anxiety symptoms, with odds ratios of 1.39 and 2.56, respectively. An underweight body mass index was associated with a lower likelihood of poor sleep quality (odds ratio 0.17), depressive symptoms (odds ratio 0.33), and anxiety symptoms (odds ratio 0.51) in female participants.</p> Conclusions <p>Lifestyle habits such as smoking, caffeine and alcohol intake, and body weight status were significantly associated with sleep quality and mental health among Syrian medical residents. Interventions promoting smoking cessation, sleep hygiene, and moderated consumption of stimulants and alcohol may improve well-being and professional performance in this population.</p> Clinical trial number <p>Not applicable.</p>