Sean and I say, "God is bigger than the Boogy Man and he's taking care of YOU and ME."
Let me tell you a little bit about my kids:
Hunter doesn't like the dark as he falls asleep, we leave the hall light on for him. But, he did suffer from night terrors for a long time. He'd sweat and kick and scream as he woke up. I'm sure you are familiar with night terrors. It's scary for kids because they are neither awake or asleep and the sensation is very weird (freaky). They scream and kick because they are just trying to cope with it or make themselves wake up the rest of the way.
There was only a short time that Hunter spoke of the "Bad Mans" in his room. We just told the bad mans to stay out and go away a couple of times and that was the end of that.
Lilly is afraid to enter dark rooms. For her it was a two fold problem; the first being a fear of not being able to see in the dark.
I thought it was absolutely adorable when her mind opened up in this way. She would turn the light off and then run for her life out of the room. She'd also dig her heals in and pull away if I tried to make her enter a dark room. How I helped her overcome her fear is by making her walk into the room (while I held her hands) and turn the light switch on (via step stool). I taught her that the light switch was the solution to make the scary dark go away.
It's good for kids to be afraid of the dark because you can't see in it, might trip over something, and it's not wise to enter dark places where you can't see what hazards are around. It think that a fear of the dark is a simple as that.
But the second fold of this problem was the ghosty. We also went through a ghost phaze. Lilly would say that she sees HALLOWEEN out the window. I'd ask her if she sees the Moon? She'd reply, "No, not the moon." Then, I'd ask her if she sees a pumpkin. She'd reply, "No, not a pumpkin." I'd ask her if she sees a ghost. She'd reply, "A ghosty is out there; mean ghosty." This started about 6-7 months after the holiday so I was very impressed with her description of what she was seeing.
During this phase we had many long conversations about the ghosty outside. She'd talk about it and repeat her comments and my comments over and over again until she was done talking all about it. Some conversation would last up to 20-30 minutes. I let her carry on like that and just remained patient as we discussed the same thing over and over. I also gave her a lot of feedback. For example: I'd stand at the window and say, "Ghosty, go away." or I'd say, "No ghosties allowed in this house. You stay out... go back to the moon." She eventually started commanding the ghosty to stay way in a big strong voice of her own. We never officially prayed on bended knee, but we spoke to the ghosty simply as children of God.
Ghosty has been away for a few months now. Both Hunter and Lilly have two ways to deal with their fears, one tangible (the light switch) and the other intangible (self-confidence -of course as children of the Almighty God).
We also read the Veggie Tales book often.
So, based on my experience... I think that the both of you have a good grasp on the situation. It may be as simple as a big imagination and it also might be a spiritual thing.
Lilly's ghosty might have been raccoon eyes in the back yard. Hunter's "Bad Mans" might have been a peeping-tom (God forbid-that's just gross). Or who knows...
Either way, God is bigger and God is the best... HE can take care of it.