My sleep playlist is as follows
Bad Plus - Flim
Shuttle 358 - Finch
Debussy - Danseuses De Delphes
Alice Coltrane - Journey Into Satchidananda
McCoy Tyner - Naima
Brian Eno - Deep Blue Day
Tim Hecker - Ghost Writing
July Skies - Coastal Stations
Harold Budd - Arabesque 2
Brian Eno - 1/1
and works a treat
Also, check out
The Lowlight Mixes blog, plenty of great ambient mixes to drift off to