To be honest, I can think of few instances where vampires do not need to sleep - and those usually involve exceptionally old and/or powerful vampires. Now is Asterion slept handing from a tree, upside down by his feet THAT would be something entertaining.
Elven trance is a nice touch though, one I can't recall seeing portrayed in other RPG's.
Need to check dwarves for agoraphobia now - maybe they like sleeping on a rock?
And by the way - SPOILER ALERT - water is....(anticipation builds) WET!!!
