I've learned to fine tune my GI process because I'm a graveyard shift worker. In order to have a family life I shift back to day shift schedule on the weekends. Some commitments during the week prevent me from getting a "big sleep" and I have to take 2 - 3 naps per day (polyphasic sleeping).
The first system to stop is the GI. Working the liquids and the fiber, senna tea when it gets real bad, keeps it moving.
Your mileage may vary!