Classical Mythology by Thomas Bullfinch is a complete telling of the great stories of the past. The beliefs, the gods and godesses, and the explanation for natural and scientific phenomena. Specifically the Norse Mythology. Read in a slow and soothing way to get you to sleep. This was a bit of an experiment, due to the nature of the content. 

Can't sleep? Let the dulcet voice of Erik Braa reading the classics take over for jumping sheep. These tales, narrated in a soothing, calm voice are designed to turn sleeplessness into somnolence. Tune in, zonk out. Bullfinch's Mythology.