I have had morning abdominal pain/soreness off and on since I was a teenager. I do not have acid reflux nor IBS. I wake up and my abdominal muscles feel a little sore but it is only painful when I take a deep breath in. The pain is not excruciating but it is definitely annoying. My internist has not been able to pinpoint the problem. This is my theory. I have a very weak core area - never had great abs - ha! I think this is a contributing factor. When I lay down for an extended period of time (at night), I believe that gravity puts pressure/extra weight on my weak abdominal muscles, causing pain in the mornings. I think that is why the pain subsides and quickly goes away after I stand and am upright for a few minutes. I tend to experience the symptoms more when I oversleep (stay lying in bed longer than usual) or I am lying on a harder surface (sleeping bag on the floor or a different mattress other than my own). I have had a colonoscopy and everything looked good although I was told my colon is about a foot longer than the average colon. Perhaps there is a correlation between a longer colon and my morning abdominal pain??