Have any severe insomniacs attempted CBT-I before?

Hello, I'm looking for general help and advice as i have and am diagnosed with severe insomnia but haven't talked with my doctor enough to be prescribed benzos (Benzos are heavily regulated where i live) and am currently on zolpidem. His general thought is CBT-I will be the most effective solution to this. Has anyone else done this sort of treatment and was it effective for you? Side note: Have any of you had sleep study's done on you and were there any results because for me there was nothing. Thank you for reading :)