In my junior year of high school I woke up suddenly one morning without my alarm clock. This never happens. I sleep like a rock, requiring an actual system of alarms that go off at ten minute intervals to make sure that in case I hit snooze on one of them in my sleep I'll have a backup.
Anyway, I share a room with my sister, who wasn't in the room when I woke. The light next to my bed was on, placing me in a little circle of light in the middle of the darkness of the rest of the house. Usually the kitchen light is on because my mom gets up for work. I got up and went out through the living room and kitchen in the dark. I headed toward my parents' room because I couldn't figure out where my sister might be. At their doorway I turned back to check the bathroom and my brother's room. The bathroom was dark and empty and my brother wasn't in his bed. He usually didn't get up until later than us because he was in middle school. There was no reason why he would be up.
I went back through the house toward my parents' room thinking they all must be in my mom's bathroom while she was getting ready. The bathroom light was off. My parents' bed was empty. I freaked out and went back toward my room where the only light in the house was. As I passed the living room an inhumanly tall, thin dark figure warped from the hallway to directly in front of me. It wasn't physical, more of a shadow, but it bore down on me and then circled me faster than any creature could have. It was gone almost immediately and I was so freaked out that I didn't even notice until I got back in my room that all of the normal lights were on: the kitchen, the bigger light in my room and one in my parents room. My sister was in my room when I entered, standing in front of the mirror. I was so confused and shaken that I didn't say anything to her, I just went to my brother's room where he was sleeping in his bed. When I went back out I saw my mom in the kitchen.
The only way I can explain this is that I never did wake up. The fact that I felt like I had woken up so suddenly is the first clue to that. The shadow-thing could have been my fear making me anthropomorphize something inanimate, enhanced by the fact that I was sleeping in the first place.