I had it a few nights ago, and I guess it's worth mentioning.

I woke up in the middle of the night. I did a quick reality check and asked myself if I was sleeping. I then went right back to sleep and right away realized I was in a dream. It hardly lasted long at all, and all I got to do was spin around and jump. It then faded and went into another dream where I dreamt I woke up and remembered that I had just had a lucid dream.

I guess that's what happens when you lose lucidity? At least it's progress