Jenna, With respect, dimished responsibility is a little more complicated by that. I accept willing disabling one's sense of reason by consuming alcohol and a sedative would not of themselves be conclusive. Of more interest is the sleep walking.
Sleep walking can be a genuine basis for an automatism "defence" - it would require careful medical assessment to determine whether that was the case. I can not help but think that no normal person (and there is nothing I;ve read that suggest this woman was not normal) would try to open a door in flight to have a cigarette unless she was temporarily not thinking logically.
I know of two people, both of whom are normal people, who have very complex sleep walking regimes. They have both engaged in complex and bizarre behaviour when sleeping - one walked but naked down a flight of stairs and started making a ham cheese and tomoato sandwich until he was directed back to his bed. People do have these conditions, and F/A need to be aware that people can do things when they are asleep that they would not do when they are awake.
My 4 cents worth - I guess an automatism defence was not presented the learned magistrate. They are quite rare and I doubt many magistrates have considered them.