For the past month or so I have been hearing a very low level humming sound. No one else hears it and I'm starting to wonder WTF is going on. I hear it mostly at night and early morning, because I'm guessing it's the quiet time of the day (night).

This humming is not constant, it sounds like an electric motor trying to cycle. I've turned off all the curcuits in the house so I know it's not from within the house. I can even hear it when I'm out in the woods or at the neighbors house.
It's really starting to bug me out!

And no it's not tinnitus.

i don't know where you are. I am in western europe and i hear a humming sound overhere too. There is even medical attention to it..