Tehran University of Medical Sciences Journal of Sleep Sciences 2476-2938 2 3-4 2018 08 04 60 66 EN Tayebe Rahimi Pordanjani Department of Psychology, School of Humanities, University of Bojnord, Bojnord, Iran Ali Mohamadzade Ebrahimi Department of Psychology, School of Humanities, University of Bojnord, Bojnord, Iran 2017 09 10 2017 11 23 Background and Objective: The optimal method of predicting mental health is the investigation of individual differences, such as identification of morning-evening types. The present study examined the relationship between components of morning-evening types, using the four components of mental health, in a group of students. Materials and Methods: The population of this descriptive cross-sectional study was all undergraduate students at the University of Bojnord, Bojnord, Iran. The participants (N = 341) were selected from this population via stratified random sampling, and they were evaluated using the Composite Scale of Morningness (CSM) and the General Health Questionnaire-28 (GHQ-28). To analyze the data, the Pearson correlation coefficient and canonical correlation analysis (CCA) were applied. Results: The canonical redundancy analysis showed that the first canonical function was statistically significant  (R2 = 0.205, P < 0.0001). The canonical weights showed that the order of contribution of independent variables to the first variate was morning affect (-0.921) and activity planning (-0.162), and the order of contribution of dependent variables was anxiety/insomnia (0.488), severe depression (0.350), somatic symptoms (0.198), and social dysfunction (0.179). Conclusion: This study showed the importance of morning-evening types as the predictor of mental health and its dimensions. Therefore, it is recommended that the morningness-eveningness preferences of people be considered in clinical interviews and diagnosis.  https://jss.tums.ac.ir/index.php/jss/article/view/74 https://jss.tums.ac.ir/index.php/jss/article/download/74/86