Today from Science News: Another article involving the important research being conducted here at the University of Rochester: Microglia had been thought to be active all the time; not so; they are most active during sleep, especially when we are not stressed (low circulating noreprinephine)
https://www.urmc.rochester.edu/news/story/5584/the-night-gardeners----immune-cells-rewire-repair-brain-while-we-sleep.aspx