I don't know how dictation programs work either, but on my iPad, if you say "exclamation point", it types ! So something similar, I imagine. You still have to go back in and edit, but at least you have something to work with.

You're in a tough spot. My hubs is a heavy sleeper, but my computer is not in the bedroom. Are you an outliner or a discovery writer? Preparation might be key. If you have an outline or solid idea to explore, when that sudden free half-an-hour pops up, you might be able to take advantage. But that's not a regular thing. Hmm.