In practice (back in the real awake world) I got into work on time, quickly wrote up the notes I'd made last night into a more readable form from which I could refer to them in the meeting, checked my email, went to the meeting, and had a constructive 2 hours (!) discussing my job, my role on the team, where I want to go, what I want to learn, how we can make the team better, etc. with my two new line-managers (I haven't moved role, we've just had a bit of a middle-management reshuffle, & they are enthusiastically and laudably being very proactive about taking responsibility for the team and setting its direction rather than just letting us all keep drifting). Anyway, I came out of the meeting with useful specific short-term goals and a better picture of some possible longer-term goals and directions (as well as some helpful input into the decisions about maternity leave and coming back afterwards). The notes I'd made were useful, and I managed to mention everything on them. Over all I ended up feeling much more positive about work than I have done for a while.
The silly thing is, it's not even as if the anxiety dreams spur me to do better; I'd already done the prep for the meeting last night (over a bagel and a large hot chocolate in G&Ds, between work and choir) because I knew I'd get more out of the meeting if I was prepared for it. The dreams just make me feel fuzzy-headed in the morning (fortunately the freezing cold cycle ride in helped with that) and worried about things where I don't need to worry.
Now to deal with all the things I do need to worry about.