When I first got into DT, I listened to ACOS a lot as I waited for sleep. Octavarium is also a good one.
ITPOE pt 2.
lol wut? That song is brutally heavily, how does that help you sleep? If anything it should give you energy and motivation to do stuff.
If I'm tired enough, I can fall asleep to just about anything. I've fallen asleep to Iced Earth and Metallica before. Maybe it is the steady rhythms that can lull me to sleep, which is why DT and odd time signatures seem to keep me awake.
However, if I'm having trouble sleeping, that kind of music is obviously too active and fast paced to help. I think some Porcupine Tree would work better, depending on the songs.