Phobia Support Group
A phobia (from the Greek "fear"), is a strong, persistent fear of situations, objects, activities, or persons. The main symptom of this disorder is the excessive, unreasonable desire to avoid the feared subject. When the fear is beyond one's control, or if the fear is interfering with daily life, then a diagnosis under one of the anxiety disorders can be made.

Its sad but I am better as I live with partner, but when he is away my paranoia comes back! I find that if I read a good book beforehand, with a small side light on then as soon as book gets put down I close my eyes and turn off the light. I don't open them again whilst it is dark and I concentrate on remembering what I read in the book.
Also use some lavender under your pillow too, help you relax.
You could even do the above but use gradually smaller lights? Or even get night lights that have a timer? So its all small gradual steps?