The ones I observed with my attending physician were using twilight sedation with propofol, and I think they got small doses of fentanyl to manage discomfort/pain during and right after the procedure. The propofol lets them knock you out for a while without putting you under so much that they have to intubate. (That is anesthesia’s job though, so it might be recorded differently on your records)
That sounds more like a waking sedation. Those will get used in American medicine if it’s just a sigmoidoscopy (the last bit of the rectum and colon), but for a full colonoscopy, they really prefer to conk you out a bit more than that.