Ok, I know what youre thinking, IS this guy crazy? Probably. But I have to go with:

Aphex Twin - Selected Ambient Works Vol. 2

This one is probably for the electro heads only. Its a 2 cd box, no track names - each track is represented by a different circle with triangles inside. I think its not ment to be listend to actively if you know what I mean its just background sounds but I find it really soothing. Its molodic & almost doesnt qualify as music. Its really ambient & I mean seriously fucking ambient. When he released it the music press thought it was a joke coz Mr James usually releases nosebleed hard-as-nails techno. Maybe its not for everyone but it works for me.:p

Pink Floyd - Animals

Most anything by Robert Miles, and yeah, Animals is great too.

Vader. The "Revelations" album.

I don't know why, but I used to sleep to Pantera's "The Great Southern Trendkill". It's heavy as hell, but there's something in the production that makes it even and cozy.

Stone Temple Pilots - Shangri-La-Dee-Da

Right on, alpha. Boards of Canada is definitely some very good "chill" music one can sleep to. Their new album "Geoghaddi" is similar, if a bit more "organic", and also quite good.

Lullaby-Creed, always relaxes me and puts me to sleep, just love that gentle acoustic guitar sound.