Can I refer you to the very bottom of my hub where I have included links to info on dreams/nightmares. Hub is called "Cautionary Tales - Beware the Giant Snail"
I touch on the subject (down the bottom of the hub) of those who are prone to nightmares being more open and compassionate than those who have few and I also detail the delicate need to handle these problems delicately. I admire your honesty.
Does this fear stem from a childhood trauma/dream or a trauma you've suffered as an adult (maybe something as simple as moving cities or losing a friend)?How serious it? Does it interfere with your ability to go about your normal business after hours?
I think that to various degree's many adults fear being alone in the dark and I admire your honesty. I have three kids and a hubby that works nightshift...and I get edgy at times, I double check the doors are locked.
At some stage it will be easier for you to face this problem then to keep avoiding it. I would encourage you to google "confronting fears(or phobia's)" or similar term and learn as much as you can on the topic.