Background: The study aimed to elucidate previously observed associations between morningnesseveningness and depressive symptomatology in university students. Relations between components of depressive symptomatology and morningness-eveningness were analysed. Methods: Nine hundred and seventy-four university students completed Polish versions of the Centre for Epidemiological Studies- Depression scale (CES-D; Polish translation appended to this paper) and the Composite Scale of Morningness. Principal component analysis (PCA) was used to test the structure of depressive symptoms. Pearson and partial correlations (with age and sex controlled), along with regression analyses with morning affect (MA) and circadian preference as predictors, were used. Results: PCA revealed three components of depressive symptoms: depressed/somatic affect, positive affect, interpersonal relations. Greater MA was related to less depressive symptoms in three components. Morning circadian preference was related to less depressive symptoms in depressed/somatic and positive affects and unrelated to interpersonal relations. Both morningness-eveningness components exhibited stronger links with depressed/somatic and positive affects than with interpersonal relations. Three CES-D components exhibited stronger links with MA than with circadian preference. In regression analyses only MA was statistically significant for positive affect and better interpersonal relations, whereas more depressed/somatic affect was predicted by lower MA and morning circadian preference (relationship reversed compared to correlations). Limitations: Self-report assessment. Conclusions: There are three groups of depressive symptoms in Polish university students. Associations of MA with depressed/somatic and positive affects are primarily responsible for the observed links between morningness-eveningness and depressive symptoms in university students. People with evening circadian preference whose MA is not lowered have less depressed/somatic affect. (C) 2016 Elsevier B.V. All rights reserved.