if you create one whole level it is possible, atm im experimenting with a gta style game, surprisingly with quite low poly models and some fog, the frame-rate doesn't seem to drop, ill have to run more tests though, and keep you posted, if you want the level to be big enough to do this, then create a dark area at the edge of the map, have a triggerzone with a teleporter there, sothat it teleports you to the floor above or below, while the player is in complete darkness ,so they have no idea that anything happened.
im not sure i answered your question like you would of liked, but there it is,
best
evil lies within all of us...we just don't know it yet