If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
I have a constant feeling that I had a great idea or an important thought just now or just a few minutes ago. I know I have recurring thoughts - not of the bad kind, mind you - that I deem quite useful but I am never sure that this feeling of forgetting is with respect to those recurring ideas or something new. Does this kind of thing ring a bell?
I used to get it while drowsy and slipping in and out of sleep. I attributed it to maybe falling into REM for a few seconds and then getting pulled out.