Irrational fears (part 1- the omnious downstairs)

I have an irrational amount of irrational fears. You might think I'm kidding or exaggerating, but I'm not. It's insanely unhealthy how many illogical fears I have and for my age, it doesn't even make sense.

I'm pretty sure everyone has had this fear as a child, especially if you lived in a house with stairs. At night, you go downstairs or down to the basement to get something. You've got your stuff, then you slowly make your trek up the stairs. You start hearing creaks and little noises behind you. Your heartbeat spikes and now you're scared. The more you try to convince yourself there's nothing behind you, the more your mind plays tricks on you. You start thinking up the most irrational things that could be behind you: an ax murderer who kills people at night and you're his/her next target, a ghost/spirit out for revenge, some psychopath who somehow got into your house and has made it his/her goal to kill you torturously and slowly, etc. Now you are sprinting up the stairs like a mad person. But wait! You forgot to turn off the lights downstairs. Shit. You run back down, take a deep breath. Calm down. You're okay. Everything is fine. You turn off the lights and sprint up the stairs like there's no tomorrow, all the while feeling something just at your heels, trying to pull you down into the darkness.

You'd think that at 18 years old, I'd have gotten over this fear, but no. I still get super jumpy and scared when I have to get something that's downstairs, then have to turn off the lights and go back upstairs. I always feel like there are invisible hands reaching for me, hungry for a helpless victim and I'm always vulnerable. It terrifies me to no end having to turn off the lights and make the trip upstairs. It makes no sense why I still fear this... I mean, I never watch horror movies, I don't read horror stories... so how do I come up with this crazy stuff? Convincing myself that there is something to be feared. My mind does have a tendency to play tricks on me and scare my shitless, so...

To this day, if I really need something that's downstairs desperately and my mom isn't asleep yet, but the lights are turned off downstairs, I will force my mom to come down with me and be the one to turn off the lights and the last one to go up the stairs. If there is something lurking in the darkness, my mom can protect me. Or the monster could get her first and I'd still have a chance at making a run for the light. My mom thinks I'm crazy for fearing this, but tell me I'm not the only one still afraid of this?