I begin to see a pattern. Excessive visiting @ this point leads on Day 1 leads to exhaustion, non-responsive sleep, and misbehavior (spontaneous attempts to extubate) on the evening of Day 1 and throughout Day 2. This is a correctable trend.
Dad was much perkier today, but still to tired to play with his letterboard - but I kept my visit short'n'sweet, relating the latest, and then bugging out before he over-tired himself. Hopefully this will prove a strategy facilitating his recovery.