Objective: Sleep quality is an important component of students’ health and may be influenced by psychological, behavioral, and physical factors. This study examined the associations of physical activity, mental health, and body mass index (BMI) with sleep quality among university students during a crisis involving military threats.

Methods: This cross-sectional, descriptive-correlational study included 333 university students from Tehran, Iran, who participated voluntarily. Data were collected using the International Physical Activity Questionnaire (IPAQ), Depression Anxiety Stress Scales (DASS), Pittsburgh Sleep Quality Index (PSQI), and BMI. Data were analyzed using Spearman’s rank-order correlations and simultaneous multiple regression.

Results: Overall, 66% of students reported poor sleep quality. Sleep quality was positively and significantly associated with stress (r = 0.524), anxiety, depression, and BMI, and negatively and significantly associated with physical activity. The regression model explained 33.8% of the variance in sleep quality. Stress, anxiety, physical activity, sedentary behavior, and BMI were significant predictors, whereas age and depression did not significantly contribute to the model.

Conclusion: Sleep quality among university students during a crisis was significantly associated with mental health, physical activity, sedentary behavior, and BMI. Stress and anxiety were the strongest predictors of sleep quality. Interventions targeting mental health, regular physical activity, and reduced sedentary behavior may help support better sleep among university students during periods of crisis. Given the cross-sectional design, these findings should not be interpreted causally.