This is the ticket for me.
I once had a ghostly encounter (was actually rather scary), but it occurred in the dark, whilst I was half asleep.
I later consoled myself with the fact that it was probably a result of my mind being in limbo between sleep and consciousness. As I suspect a lot of encounters are.
Same thing happened me, woke up to see a women who I thought was robbing the place. Said I better keep quiet. Terrifying stuff all the same!