Use your flashlight to ward off the Boogeyman, it seems to be the only thing it fears.
There are four ways into your room; The door, closet, window, and air vent. Watch them carefully.
The bedside lamp, nightlight, passage light, street light, and even the moon light help you to see around the room. (Staring directly into light will glare your vision).
The moon will change cycles each night. Full moon, half-moon… no moon.
Your battery will only last so long. Conserve as much power as you can by relying more on the sounds around you.