Where Do You Go To?

I've been ploughing through the editing for my last manuscript and, as always, it's taking waaaay longer than expected. However, I'm nearly up to the uncharted territory... the stuff, well, the stuff I have very little recollection of writing.
I remember getting up to make teas, coffees or hot chocolate. I remember occasionally looking up at the tv. As to what I was tapping away? Not so much.
I remember what I intended to write, my plans and drafts, but... I've still 100 pages left to edit, I'm not even halfway through, and from here on in, the stuff I haven't really edited before, my memory is not so good. Seeing as I wrote it in a big chunk only a week ago, that strikes me as a little bit strange.
It's happened before - this odd non-remembering, and it's always a sign I am, or was, on a roll. Whether it was a good roll, I've yet to determine, but I do find the process interesting.
How about you?
Do you go 'away' when you write?
And where do you think it is you go?
Is it just immersion in the story - living it - or something else?
(Hint: I'd prefer it if you don't say early onset dementia. Generally my memory is bad, but not that bad!)