strange posted:D.D...... I experience similar as yourself; not so much a fog but a level of fatigue which never seems to lift.
I believe our symptoms could be a salt deficiency; either we must add more salt to our diet or more potassium, maybe both.
I’ve even been referred to the Endocrinology Dept of my local Hospital, had various blood test which reveal nothing out of the ordinary.
Once our colon is removed, we no longer have the ability to absorb fluid and salt from our waste whilst we sleep; which in my opinion, is exacerbated by the creation of the J pouch.
I did not know about the colon's function regarding salt, but I do know that I often crave salt. My worst time is the a.m. and coffee definitely was making it much worse. I think I need to try sipping on water during the night though, as when I wake during the night I have dry mouth.