knockout trap

I was slept by a knockout trap for 4 hours duration. At 0 or 1 hours duration remaining, a mob wandered into the room and triggered the trap (while I was still sleeping). This reset my sleep timer to 4 hours duration. Maybe traps are different, but most sleep spells/abilities can't be "re-upped". This has potential to "permasleep" a character, depending on wandering mob density.