false awakening

I was in a long dream (which I couldn't recall) then slipped into a FA. I woke-up and opened my dream journal to write down the dream I had. I wrote a whole page of the dream (I was experiencing every second of writing it) then went back to sleep and woke-up for real only to find that the page on my dream journal is empty, I was confused for a while until I realized that I have experienced FA.