From my own recent experience, I do think a lot of bowel symptoms are fairly common. I had a clear colonoscopy three weeks ago but spent so long aware of my bowel habits that I am still noticing "I had loose stools last Monday and went to the loo more frequently than usual on Saturday and had a slight pain somewhere some other day and possibly had a bit of constipation this morning..." My brother pointed out to me while I was waiting that any symptoms you only noticed after you were told you needed a colonoscopy probably aren't that significant.

I really didn't find the sedation noticeable at all. I felt wide awake and was talking to the team doing the colonoscopy. I also didn't sleep afterwards when you are supposed to. I did find afterwards that I had missing parts in my memory - weird missing parts like I'd remember one sentence somebody said but not the one before it or something. But at the time, I had no sense whatsoever of being sedated.

Your brother is a wise man!  Since finding that I had an abnormal test, I have had all manner of aches, pains, bloating.  I am becoming obsessed with going to the toilet and what I might find!  I have always had IBS for years, so loose stools is the norm for me.  Now, I have convinced myself that I have a huge tumour lurking somewhere.  Still not sure about sedation but will take it if they say I should.