A machine learning–based analysis of chronotype and sleep quality as predictors of mental distress in university students

This cross-sectional study aimed to investigate the combined effects of chronotype, Mediterranean diet adherence, and sleep quality on mental distress in university students, and to identify key predictors through advanced statistical modelling and machine learning approaches. A total of 659 undergraduate students aged 18-30 y in Konya, Türkiye, participated in the study. Chronotype was assessed using the Morningness - Eveningness Questionnaire (MEQ), sleep quality with the Pittsburgh Sleep Quality Index (PSQI), Mediterranean diet adherence with the Mediterranean Diet Adherence Screener (MEDAS), and mental distress with the Food-Mood Questionnaire (FMQ). Pearson correlation analyses, hierarchical regression, and path analysis were conducted to examine associations and potential mediation pathways. Additionally, an explainable XGBoost model with Shapley Additive Explanations (SHAP) values was applied to identify the most influential predictors of mental distress. Poorer sleep quality and evening chronotype were significantly associated with higher mental distress. Morning chronotype was positively associated with MEDAS but not with Body Mass Index (BMI). Hierarchical regression indicated that PSQI was the strongest predictor of mental distress, followed by chronotype. Path analysis further revealed that sleep quality significantly mediated the relationship between chronotype and mental distress, whereas Mediterranean diet adherence did not show a mediating effect. The XGBoost model demonstrated robust predictive performance, and SHAP analysis confirmed chronotype and sleep quality as the most influential variables in predicting mental distress. Evening chronotype and poorer sleep quality were associated with higher levels of mental distress in university students, while dietary quality did not show a significant independent association with mental distress in this sample. These findings highlight the importance of interventions focusing on circadian alignment and sleep hygiene to support mental well-being in young adults.