The relation between sleep and violent aggression

Good sleep is important for our emotional stability and aggression control. Although most people do not become violent after a period of poor sleep, this may be different for certain vulnerable individuals. Forensic psychiatric patients may represent a group of such individuals. We studied patients who committed a crime, often violent in nature, but are not completely held accountable for this due to a mental disorder. They usually get sentenced by the court to follow treatment.

A novel finding in this thesis is that poor sleep quality is highly prevalent among these forensic populations. The more sleep difficulties these patients experience, the more impulsive and aggressive they are. Individuals with violent traits appear particularly poor sleepers. The causal relationship between sleep quality and violence was studied in an animal model of violence. We found some indications that also violent rats differ slightly from non-violent rats in their sleep patterns as measured by brain activity after exposure to challenging conditions. Moreover, lack of sleep in rats causes increased impulsive behavior.

The effect of sleep loss on the prefrontal cortex, a brain area which serves as the “brake” for our behavior, is likely to be responsible for the negative effects of sleep debt on our behavioral inhibitory capabilities. More work needs to be done to understand the neurobiological mechanisms underlying the relation between sleep and violent aggression. Treatment of sleep disorders may open new avenues for the development of aggression control in forensic patients.