Title and Running Title: Conscientiousness Predicts Diurnal Preference

The relationship between diurnal preference, as measured by the Horne-Östberg questionnaire, and quantifiable personality traits was investigated in 620 participants. A hierarchical multiple regression demonstrated that conscientiousness was the single biggest predictor of diurnal preference (beta = 0.26), after controlling for depression, sleep disorders, shift work, age, gender, and demographic characteristics. Morningness has previously been associated with physiological parameters of the circadian clock and with polymorphisms in circadian clock genes, suggesting the possibility that conscientiousness, too, may be linked to the same parameters. Hogben et al: Conscientiousness predicts diurnal preference 3