ghosties

Last night as I was in bed, just dropping off, in that intermediate stage between sleep and wakefulness when I heard a loud crack from the ceiling and then a noise as though someone was wandering about in the loft. I saw a figure walk past my bed. I sat up and looked around but of course the room was empty.
Maybe just the house cooling down at the night moved in.
I settled down to go back to sleep. Again just as I was dropping off another crack from the ceiling. I looked around. still nothing.
Again I settled down and went to sleep.
Definitely a bit of an eerie experience.
What does it mean ??