Open Question: Im 18 and im scared of the dark?

i have to ask my little brother or my sister to go downstairs with me when its night time because i feel so lonely and vulnerable. this isn't just periodically happening, its all the time and i dont know why. i guess that its so quiet when i hear a noise i put too much attention towards it. my lil bro and sister makes fun of me for being the buff dude who can't even go in the dark by myself. ok end of story time, how do i put an end to this?