Hello,
I've had a colonoscopy w/o sedation (not even conscious sedation) in the US. The doc said that I was his one person a year who requested no sedation. Since there are no nerve endings in the colon, there's no pain and no need to stay for an hour after the procedure waiting for the sedation to wear off. I'd recommend giving it a try. In Europe, no sedation is the norm.
Take care.
Regina