Paranoia of dark?

Ok i notice that when i try to sleep in pure dark rooms, basically no light, i cannot. i have to sleep with a light outside my room and the door abit open. Is this paranoia? or what? how do i get over it? its like when it’s dark i have this constant fear someone is in my room, it feels so real like i can just feel somthing there i cant stand it and i look around in the darkness and just end up opening the lights outside. Anyone else have this paranoia or fear and know how to conquer it?