Guys! WAS IT PETER?

It was at night, I think around midnight, and I was asleep. I suddenly awoke because I heard a loud noise, like something falling of something being knocked over, and I saw a flash of movement out of the corner of my eye. I don't have any pets, siblings of anything. My bedroom door was closed. I think my window was open. I looked round to see if anything had fallen off my shelves but everything was in its right place. Was it Peter? And what do I do if he comes back?