How to stop being so petrified of the dark ?

I'm 13 and I feel childish because I'm soo afraid of the dark.. When I was little I wasn't as much, but now I'm extremely petrified ever since 8yrs old I feel like something might drag me off of my bed or try to possess me or something... Around the same time I began going to catechism. Might those be attached? I've told my parents and siblings of me afraid of the dark but they only make fun of me and call me stupid and my dad locked me in the dark once to "knock the fear out of me"..