I actually understand what your saying a lot. I like to play poker in the morning for a few hours while drinking coffee.
I have had remarkable success with this, as I am more alert in the morning, my environment is quiet, and the coffee serves me well.
If I try and play at 10pm on a Saturday night I generally find myself down a few buy ins at 3 in the morning, confusing spades with clubs and trying to figure out how that donkey called my 3barrel with 2nd pair.
the lesson to be learned is that extended sessions destroy your profit. Placing a timer, and possibly a stop gap for losses, are both effective methods of being disciplined.
Like I said, I used to have 8 hour sessions and by the end I would actually be thinking I was value betting flushes when I had clubs and not spades