Associations between the athlete diet index and sleep quality in Iranian professional athletes: a cross-sectional study

BACKGROUND: Sleep quality is a key component of recovery in athletes, yet sleep disturbances are common in this population. Although dietary quality has been proposed as a lifestyle factor related to sleep, its association with sleep quality in professional athletes, when considered alongside other relevant factors, remains insufficiently understood. This study examined factors associated with sleep quality among Iranian professional athletes. METHODS: This cross-sectional study included 340 professional athletes aged 18-29 years. Dietary quality was assessed using the Athlete Diet Index (ADI), sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI), and anthropometric characteristics were obtained using standard procedures. Multiple linear regression analysis was conducted to identify independent factors associated with the global PSQI score. RESULTS: The Multiple linear regression model was statistically significant (adjusted R² = 0.269, p < 0.001). Lower scores on the Specific Nutrients subscale (β = -0.238, p < 0.001) and the Core Nutrition subscale (β = -0.299, p < 0.001) of the Athlete Diet Index were independently associated with poorer sleep quality. No significant associations were observed for body mass index, Dietary Habits, age, or sport type. CONCLUSION: In this cohort of Iranian professional athletes, dietary quality particularly core nutrition and specific nutrient intake was significantly associated with sleep quality. These findings highlight the potential importance of overall dietary quality in relation to sleep health and recovery among athletes. However, due to the cross-sectional design of the study, these associations should be interpreted with caution, and causal inferences cannot be drawn.