Its always either Tangerine or Thats the Way - Led Zeppelin... I always wake up to The Lemon Song though... its strange... its become a little sub-conscious bodily routine for me to fall asleep and wake-up to these songs.
usually something like John Prine, Keller Williams, Phish, Xavier Rudd, some lighter Allman Brothers stuff, Grateful Dead and occasionally James Taylor or something
I have some sleepy playlist music that's mellow and so good for drifting. Tracy Chapman is on it- i'm loving 'Warm Embrace' at the moment. The rest of it's a mix - Iron & Wine, some Cat Power, Bic Runga, some Ben Harper, some Reindeer Section, Nick Drake, the score from Donnie Darko (it's so pretty), and yes stuff like that. Slower, more dreamy music is what helps me relax enough to sleep.
Pink Floydd! for sure. Actually pretty much any good slow song, I actually have a slow song playlist haha