From what I have read in the bible. The spirit goes to sleep after the body dies. An example of this is The prophet samuel. When the King Saul summoned his spirit after he passed away. Sameuel said something to the effect of why did u awaken me.
So if we look at it from that aspect i guess the spirit can be troubled after the body passes away so rest in peace is not a false term. But im wid u on repeating sayings dat dont make no sense. jus like u said Bless u when somebody sneezes.