I'm staying up until 3 because I'm scared. How can I get to sleep fast and get rid of my fear?

Almost every night I stay up until at least 2:00 because I’m not that sleepy and I’m so afraid of the dark! I keep thinking that something is going to walk down the hallway to my room or pound and scream at my window! I mountain biked three miles today and that made me a little tired, but it also made my body wake up and it was earlier in the morning! I get in bed sleepy at 11:00–12:30 usually but end up not falling asleep until 2:30. One night I stayed awake until 6 in the morning and it was getting light outside when I finally fell asleep! I’m so sick of being scared and staying up until the middle of the night! How can I stop being afraid of the dark and get to sleep fast? I mean fast, like thirty minutes after I lay down. Any ideas?