Trouble concentrating....?

[Python49]

Ok, i've gotten very very good at controlling tilt and going off the deep end. I can really control my emotion just fine nowadays even after strings of suck outs in a row. One problem i've still been encountering on occasion is that some nights I just can't concentrate to save the life of me. I do play 10-12 tables at a time for the most part, but the MAJORITY of the time I can actually keep tabs on how people are playing, their style, what's going on, and the general flow of the tables i'm at. Hell, sometimes I have such clarity of thought and am naturally picking up on every single detail at my tables and feel like things flow fluid.

Then theres other nights where I can't concentrate on ANYTHING. Hell, it's like even if I were just at 4 tables I couldn't tell what's going on. My mind will constantly wander on something other than the game and i'm left auto piloting, then 15mins later after I make a mistake it's like i'll then realize "wtf, i'm not even paying attention, just going through the motions and auto piloting". I'll also log off AIM at this point usually but still just feels like so much more effort to concentrate than it should. Maybe tired or something.

Anyone else notice this difference in ability to concentrate? What do you do? And yes i'd accept the recommendation of playing less tables if it weren't for the fact that probably 80% of the time I play this many tables I can concentrate on reads/play just fine.