Here in the UK you just get pain relief, and are generally conscious for the procedure - though gas and air is available if it is uncomfortable.
It caused me no pain at all, was quick and easy and I'm pleased I went ahead with it.
My father found he had bowel cancer from a routine fecal occult test they were sending to all men above 65 in my area. He took some convincing to do the test, but found he had cancer and was swiftly operated on. My older brother found he had it far younger, about 52 and his was far more advanced when it was discovered, and 5 years of treatment later it won't be something they can cure. So it is pure chance my father's was caught so early and was so successful.
After speaking to my gp they agreed to start my colonoscopy cycle at 40 - with one every 5 years until I hit 55 and then likely more frequently.
I was a little nervous but it was totally fine and I feel freed that it is one worry that is if not behind me, that is controlled.
Top tip is to follow the instructions of the laxatives well and eat nothing except a broth or miso soup, and it will be far easier on your gut.