That's what worried me, the fear taking over. A few years back I lived on my own in a little flat. The front door (and only way out save jumping out a window a few floors up) went onto a long corridor, bit like a hotel/hall of residence type.
I was woken up one morning by someone trying to get into the flat. Initially in a really freaky way, they were quite slowly pushing the door handle (one on both sides) down and back up again, over and over then would walk up the corridor a bit then back and do it again. Scared the hell out of me, really freaked me out as the doors really weren't that secure and I just didn't know what to do. I was scared about making a phonecall to the police in case they heard me in there so, in the end, waited until they had gone up the corridor to phone. All credit to the police, they had two officers with me in about 10 minutes but they didn't get whoever it was, probably legged it when they heard them coming.
Happened again a couple of times. Trying to get through the letterbox was one time as the doors were designed to automatically open from the inside even if locked so people would try and break in that way.
The flat was only tiny so my bed was right near the front door and no other way out and I was on my own. I'd just be there terrified, trying to be quiet and hoping they would go away.