Many things happened to me (and my family) in the house I grew up in, and actually, other places as well. Some of these occurences happened when I was young, and I know childhood memories aren't always accurate, but my family remembers this.
I was sleeping downstairs in the living room on the couch, and I assume this is because I wanted to stay up late watching TV. I woke up to my back being hit. I was sleeping on my side, and though it didn't really hurt, it was uncomfortable. My brother's room was just down the hall so I thought he was just messing with me. I remember saying "Hey, [brother], that's not funny!" without opening my eyes. But I didn't hear anything - no footsteps or giggling, nothing. So I open my eyes, got up and scanned the room, looked behind the couch and I didn't see anyone. I was pretty scared while looking around because I thought my brother was going to jump out at me and scare me. Still, I checked my brother's room and the door was nearly all the way closed - he was fast asleep inside. I realized it was quite early in the morning and I was the only one awake.
TL;DR Something punched me in the back, waking me up.