For me, it could be a song from 'Powerslave'. Shogun represents Bruce Dickinson and his skills in fencing. Ozzy and Lemmy could represent Bruce ennemies. The "x=5" is maybe an indication of the 5th album, 'Powerslave'. I'm hesitating between "Powerslave" and "Rime Of The Ancient Mariner".
Well, I'll say "Rime Of The Ancient Mariner" for its daydream side and the clue "Sleep now but remember to wake up !". And about the clue #1, the flies, there is a verse in "Rime Of The Ancient Mariner" that uses the word "flies" : "Through the snow fog flies on the albatross".