ectoimp: Dannys bedroom acts as his lair. As such there is a large amount of ambient ecto energy in the room. A ghost lair serves as a sort of safety net to a ghost that may have sustained injuries, or has become exhausted. The energy that collects in their lair can be use to speed up recovery time. This is why in mystery meat sam and tucker bring danny back to his room to recover instead of one of their homes.