Morning affect, eveningness, and amplitude distinctness: Associations with behavioural indicators of...

Morningness is associated with well-being, better sleep quality, and more conscientiousness, while eveningness is associated with negative emotionality, poorer sleep quality, and less conscientiousness. The current study aimed to further understanding of associations with conscientiousness by assessing specific behavioural indicators of conscientiousness, morningness-eveningness, and also the Morning Affect and Distinctness (amplitude of diurnal variation) aspects of circadian functioning. A survey of Chinese university students (N = 369, aged 18-30, mean = 19.48, SD = 1.922; 108 males, 261 females), included the Morningness-Eveningness-Stability-Scale, measures of conscientiousness, mindfulness, life satisfaction, aspects of sleep, and the Behavioural Indicators of Conscientiousness (BIC) scale. Morningness and Morning Affect were positively correlated with life satisfaction, mindfulness, better sleep quality, more conscientiousness, and with BIC including Hardworking, Self-control, and Punctuality. Distinctness showed negative correlations with these variables. Negative correlations between Eveningness and conscientiousness, and the BIC subscales of Hardworking and Cleanliness were no longer significant after controlling for Morning Affect. Mediation analysis showed that the associations between Eveningness and conscientiousness/BIC were mediated by Morning Affect. These results extend previous research by showing associations between circadian functioning and specific behavioural indicators of conscientiousness, and suggest that low Morning Affect may provide a mechanism for the relationship between Eveningness and conscientiousness.