The first thing I would do is not worry too much. You CAN grow out of this, you can conquer this.
I have OCD (the real kind, lol) and although it's pale in comparison to what it used to be, I had the exact same problem as you until I was 13. I despise darkness and the absence of light and activity. Most people call going to sleep in a cold, dark, noiseless room bliss; I call it hell. I have to have my computer on at night, usually playing some funny show I like. I put the volume on low and the contrast of my monitor on low so it's not too bright. The idea that something is going on makes me feel like someone is there and that everything is okay. I have no idea if this will help, but this is how I sleep most nights unless a friend is staying the night or something.
Another thing to consider is your life in the waking world. If you are stressed, it will carry over into your dreams and affect your sleeping in general. Stress is also exacerbated by a lack of sleep, as someone pointed out above me. Trying to fix things in your life, if anything's wrong, may help put your mind at ease.
I hope we've at least helped a little bit.
