I refuse to have my front door unlocked at any time, mainly because we live in a shared access building comprised of three flats which just happens to be next to a brothel. I have no idea who the people in one of the other flats are, and we get a few drunk blokes in who wanted the brothel and got the wrong building.

I also sleep with my bedroom door shut, although I'm not really sure why, as it's now a subconscious action to shut it. It might well be from when I was young, and had a bad habit of having very realistic nightmares and then waking up and seeing things in the shadows. If the bedroom door was open as well then my imagination would fancy various bad things lurking in the hallway, and if it was shut there was always the possibility they couldn't come in.