"Circadian clock circuit may control daily rhythms of aggression"

“We examined the biological clock’s brain circuitry and found a connection to a population of neurons known to cause violent attacks when stimulated in male mice. We wanted to know if this represented a propensity for violence at certain times of day,” he said. 

Saper and colleagues observed aggressive interactions between male mice. They observed the resident mice defending territory against intruders introduced to residents’ cages at different times throughout the day. Counting the intensity and frequency of residents’ attacks on intruders revealed for the first time that aggression in male mice exhibits a daily rhythm...

“Our results in mice mimic the patterns of increased aggression during the early resting phase seen in patients during sundowning,” said first author William Todd, HMS instructor in neurology at Beth Israel Deaconess."

https://hms.harvard.edu/news/evening-sun-0?utm_source=Silverpop&utm_medium=email&utm_term=s2&utm_content=4.16.18.HMS