I think a lot of anaethetists do things differently for different people. You should tell them that this happens to you. It is possible to have other forms of sedation if you don't cope well.
I also don't cope well with anaesthetic so I can sympathise competely with you. Everyone else is sitting around drinking a cuppa and eating a sandwich, and I am semi-concious with my head in a bowl!
If i was doing it again, I would be talking to the FS and the anaesthetist and trying to come up with something that suited me better.

Good luck.
Jo