I have ulcerative colitis so have had many many colonoscopies. General anaesthetic is never used in UK but twilight sedation is normal. I refuse this as (after an unpleasant gastroscopy) I can't stand having tubes stuck up my orifices while I'm unable to fully intellectualise what's happening. They're usually happy to give a bit of fentanyl instead.

My experience is that GI doctors enjoy chatting during the procedure but specialist nurses (who often perform minor endoscopies) are usually not very communicative.