Hi Rhonda,
My son, who is 16 now, also was afraid for years of being alone, and I attribute it to TV. Every time he would watch a suspenseful movie, it would come back. I was also a single mom for years and I always had him sleep with me when he was younger. His father and I divorced when he was 5, but we were on and off, since he was a baby. So he didn't exactly have the most stable little beginning. I just let him sleep with me. Our favorite activity at night was to read together. I would find a series of books he liked, and at first I was reading them out loud, then later we would just lie in the bed together and read our own books. I don't believe the tough love of forcing them to sleep alone addresses the issue and I always chose to solve the problems with love. My husband now and I have been together since my son was 6, and we lived on a boat for years and he didn't have a room of his own. My husband snores so after a while, he and my son just shared the futon in the living room lol. Then we moved into a small apartment when our daughter was born, and there was only one room, so the baby and I got the room, and my husband and son still got the futon in the living room. I truly believe all this closeness in proximity brought us closer together as a family, and even though we now have a house and everyone has their own room, I will still go back and forth between my kids rooms. My son still loves to have me or his step dad sleep with him, and my daughter has recently been weaned from nursing, so I still spend part of the night there. and of course my husband still snores, so I can't sleep with him lol.
I know this doesn't address his fear, but if he gets a good night's sleep, where is the harm in it? He will eventually grow out of it. Be thankful that you don't have a worse problem like bed wetting or night terrors. My husband has always been supportive of my sleeping with my kids, and that has really helped. We are all extremely close now and I have a wonderful son that still talks to me, even at 16, how rare is that! I fully believe that it will take care of itself in time, unless you force him to just live with his fear.
Also the suggestion of getting him a dog is a great one. There are a lot of really great family dogs on craig's list that need loving homes, and that way is usually free or cheap, and you don't have to go through that destructive puppy phase. We just got a one year old dog off of craigs list and we love her to death and she came spayed already.
Have you tried talking to him about his fears? Do you lay in his bed with him or welcome him in yours if he is feeling fearful? I know a lot of people don't believe in this practice, but I originally did it because it was easier, and continued it because we all like it. And it isn't a problem for us.
I also know of an acupressure technique that really helps with emotional issues called EFT, or emotional Freedom Technique. Try surfing it up on the internet.
I have read that children that sleep with a light on, even just a night light are more likely to develop leukemia or other forms of cancer, so I wouldn't recommend that approach. Complete darkness is the best way to sleep. It stresses our bodies for a light to be on because it messes with our melatonin production which stresses our immune systems. Try soft soothing music like Enya or white noise like a small fan instead.
Good luck and best wishes.