Actaully as far as plants go, it is reccomended not to use a bubble wand, or anything else that will agitate the surface of the water, especially if you are injecting co2 as this will gas off the co2 before the plants can use it.
Bubble wands are not needed for the majority of tanks. There is enough dissolved o2 in the water for fish without them. Some exceptions are if you have to increase the temp of your tank to treat for a disease, or if the tank temps rise do to surrounding enviroment (higher temps result in less dissolved o2 in the water), sick fish to ease there respiration.
So, the answer to your question is, yes it is OK to turn your bubble wand off at night, and it is OK to not have one at all , under normal circumstances they aren't needed.
Blue