I first lived on my own at 17. I was ridiculously stupid and used to walk to the 24hr garage in the early hours of the morning and other silly things. At that age you don't (or at least I didn't) think of the dangers.
I went to Australia then when I was 19 and had the most frightening experience of my life. I thought I would die that night and have been a nervous wreck ever since.
People, including my mother, think I'm deranged but I can't help it. I'm considerably better now than years ago when I used to stay awake all night because I was petrified to sleep in the dark. At that time I used to lock every internal door in the house, tie a rope from the loft hatch to the radiator in the hall because there was an attic window, keep a can of hairspray and a lighter under my pillow along with a kitchen knife and sit 'on guard' for the night. If I fell asleep I would wake up in a sweat and have the most awful panic attacks. They were horrible years and to a great degree, the paralysing fear has stayed with me...so much so that I've been studied (by psychology students)
My night-time routine when I'm alone is always the same, double check all windows, leave one dog out the back and bring one of them in (the one who does weewees is the lucky one that gets in) so that the front and back of the house are guarded, set alarm(monitored 24hrs), lock all internal doors (with keys left in place in case of fire), bring panic button to bed, landing light on, dd into my bed, lock bedroom door, use the remote to check that I have DEFINATELY set the alarm, turn on the tv so I don't feel so alone but no sound in case I don't hear something I should. Worry that someone will poison my dog out the back with rank meat and get in to us, then usually wake up thanking my Nana for watching over us that night.
Post traumatic stress, it rules my life no matter how irrational I know I'm being. It's a nightmare.
Sorry thats so long.