On edge: night and day. Understanding the association between poor sleep and aggression

Sleep plays a pivotal role in mental well-being, including emotion regulation and self-control mechanisms. Disturbances of sleep appear to contribute to aggression. This association might be of particular importance in psychiatry, where sleep problems, impulsivity, anger and aggressive behavior are highly prevalent. In this dissertation, various study designs were used to investigate the association between poor sleep and aggression. Two systematic reviews and meta-analyses were performed to summarize existing data on the associations of sleep quality and sleep duration, respectively, with measures of aggression, such as anger and hostility. We were able to aggregate a large number of observational and experimental studies, which together indicate clear and consistent associations between poor sleep or short sleep and higher aggression. Importantly, this association proved to be more pronounced in people with psychological vulnerabilities. Furthermore, in an original data-analysis of a cohort of forensic psychiatric patients, we explored the association between sleep quality, impulsivity and aggression. Poor sleep quality was associated with higher self-reported impulsivity and aggression. Looking at the longitudinal association, we found that poor sleep quality was associated with higher aggression over 1 year in this patient group. These associations were not better accounted for by psychiatric diagnosis or general level of psychopathology.Although the work presented in this dissertation does not directly investigate a causal relation between sleep and aggression, the results do imply that restoring sleep might be a new and important potential strategy to reduce anger, hostility and aggressive behavior especially in (forensic) psychiatric patients