Leaving an NES powered on overnight?

I really wanted to beat every level in Mario 3 in one sitting, and I just got to World 8 and it's kicking my ass. I really want to put it down and finish it tomorrow since it's getting late, but Nintendo didn't put in saves or even passwords :/ Would it be safe for me to leave the NES powered on so I can pick it back up tomorrow? Or will that damage some of the parts in the NES?