I disagree with Phil. The circuit box provides power to the circuits. The lights are controlled by the switches. If the switches are single pole single throw, then there is no way they can switch on and off by themselves - unless you have ghosts. Double pole, single throw switches (also called three way switches) operate a little differently. One switch can turn a light on, the other can turn it off. However to do what you are describing, it would have to have been deliberately wired that way.
Once I lived in a house (duplex) where both homes had a switch to control the garage light. Since the light was powered from my meter, I'd switch it off, but my neighbor would switch it back on for security reasons. One day I just had enough and replaced the three way with a single pole switch and took final control of the light. He was upset, but at least he wasn't spending my money.
OK, this means little to your problem. Without more description of the circuitry and the events I can only guess. Now, assuming all wiring is correct, and assuming to turn the light on you must flip the switch UP, and assuming that at night you flipped the switch DOWN but woke up and the switch was UP again, maybe you're sleepwalking.
Good luck figuring this one out.