Is it possible, through proper sedation, to be awake, aware, relaxed, and pain-free for a colonoscopy?

Maybe: The colon it self only feels pain through stretch. So it depends partially on the shape of your colon and the skill of of the colonoscopist. So it is possible under ideal circumstance to have no sedation. But usually pain and sedative medication is required. The amount required and therefore your levell of awareness will depend on how much pain you are having.

Maybe, Usually No: For this, partial to full anesthesia routine, often with agents which block memory, e.g. Versed. Why? People don’t complain-of/remember pain + makes exam much easier & faster for md. I had exam with Demerol (meperidine hydrochloride) 50 mg IV alone; fine through the 1st 2/3 & still remember the images on screen; then intense intestinal cramping began, could not stop it consciously, given 50 mg ? & passed out. Awoke later ok.