A big part of the day to day and hour to hour roller coaster is quality of sleep and intensity of cognitive effort. It is very easy to overload the PCS brain with sensory stimulation or cognitive effort. It is also difficult for the PCS brain to get good sleep. Both make for quite a wild ride.

We have a term for this question in my house. "Is this a driving day ?" It relates to how well I am able to process and tolerate my days' tasks and environment.