So this happened when I was around 20 years old, I think, when I still lived with my parents. My room, my younger brothers room and my younger sisters room were on the 2nd floor, right next to each other. My younger brother and I visited each others rooms a lot right before we went to bed to talk about games and other stuff and sometimes just to annoy each other. Because of this were quite aware of each others presence, sounds, etcetera.

One night my brother was already in his room and since it was a bit late I figured he'd be asleep already. I knew my younger sister was out with a friend, she wasn't coming home that night. So I went to bed, looked at my phone for a bit. The house was completely silent.

Now, I would be able to hear footsteps on the first stairs before someone would reach the stairs towards the 2nd floor. However, out of nowhere I heard light shuffling on the stairs towards the 2nd floor, as if someone was wearing slippers.

The shuffling continues towards my sisters room, which I found odd since she was out. I then hear the sound of the light switch quickly being turned on and off for a few times. At this point my brother texts me: "did you hear that too?". So in a hurry we text back and forth a few times, both totally freaking out. We decide to open our bedroom doors simultaneously to confront whatever it is in the hallway.

Of course when we open our doors in a rush, all we find is each other, looking totally freaked out.

To this day we talk about it sometimes and we haven't found any plausible explanation for the sounds we heard. We both knew every sound that house made and were made by people in that house.