Aggression in young adults--a matter of short sleep and social jetlag?

Evening orientation and sleep duration have been linked with aggression and problematic behaviors, but no study has used an explicit aggression questionnaire. The present study used the Buss-Perry Aggression Questionnaire based on physical aggression, verbal aggression, anger, and hostility, as well as questionnaires on the timing of sleep and sleep duration to assess this relationship in young adult men. The Composite Scale of Morningness was used to assess circadian preference; sleep-wake variables (wake time and sleep onset time on weekdays and on weekend days) were used to calculate midpoint of sleep, social jetlag, and sleep duration. Results indicated that sleep duration correlated negatively with verbal aggression, physical aggression, and anger. Short sleepers were more aggressive. Using multivariate analysis of variance, shorter sleep duration was a significant predictor of verbal aggression and anger. Concerning physical aggression, social jetlag also contributed to the model. Morningness-eveningness was associated with the hostility scale with eveningness related to higher hostility. Men scored higher than women in physical and verbal aggression.