Author's note: I've been waiting to share this with someone who won't think I'm completely crazed. This wiki seems like a great place for that. So, let's start. I like to call this theory "Lucid Nightmares", or "Down the wrong track".
If you could, I would really appreciate some feedback/constructive criticism in the Talk section. Thanks, and please enjoy.
The more I think about it, I realize Jeff and Slenderman are obviously fake. So are ghosts. (Obviously.)
And everything "supernatural" is obviously fake too. We don't need to worry about things like that. But, our brains were created to help us; to aid us. which means we are scared of those things for a reason. It's a self-defense mechanism, really, made by our brain.
Our brain bases things off of details. That's why were scared of the story about Slenderman and Jeff. It was realistic. It is also why we're scared of scary pictures and movies. They're realistic. We know (or at least, fear) that those scenarios where Slendy tears you to bits, or Jeff will tell you to "Go To Sleep", they can actually happen. Now, like I was saying, deep down, we know those things are fake. We use reasoning. Another survival tool. Humans can use reason.
What's the closest object to your left? Let's pretend it's a calculator. Now, if I told you that calculator was about to pull out a rocket launcher and blow you to bits, you obviously wouldn't believe me. But, if I gave you decisive proof and reason to believe it, you would be petrified and smash that calculator into oblivion. So would I, and any other reasonable person.
Now, we dream about things. If our brain doesn't have details, It can't picture things. But with details, your worst Nightmare is real.
Now, mix details and lucid dreaming together. What do you get? Lucid nightmares. Now, if this dream would never end... Dreams can last ten seconds, then wake you up. Or last half an hour. Now, the average person sleeps for at least eight hours. Imagine an eight hour long lucid nightmare.
According to different sources, a supreme shock to your body can give you a heart attack, killing you. Now, I believe an eight hour long lucid nightmare is enough shock to kill anyone. And remember, lucid dreaming is exactly like real life. Also, what you think about before you sleep determines your dream. Heh heh. Now, people think dying in your sleep is peaceful. I highly doubt it.
When you're older, your immune system goes down terribly. Now, before, as a kid, it requires a huge shock to the system to do damage. As an elder... It takes the slightest shock for a heart attack. Maybe, just maybe, when people die in their sleep, they've just been in a lucid nightmare. They've experienced their own personalized version of Hell.
Now, my main point is that the most likely thing to kill you isn't a gun. Or a knife. Or another person's fist. It's your own mind. Speaking of minds, they say the human brain is the most advanced one. Now, while having an advanced brain, you must care for it. Like a nuclear weapon. One false move, boom. Everyone falls down. (And never gets back up.)
If it malfunctions, or goes haywire, (if you go insane) imagine what you could do. The sheer amount of possibilities you could do with a weapon such as the most advanced mind in the world... No, the galaxy. Now, add an insane mind, a few blades, maybe even a gun. What do you get? Murder.
Anyway. Insane people say the "voices told them to do it". The voices that were, perhaps, in their lucid nightmare? It takes something pretty realistic to scare someone so bad, they would commit murder. Something like a lucid nightmare. Wouldn't you agree?
You shouldn't worry about those fake monsters on television, or on Creepypasta. Or even murderers, come to think of it. You should worry about yourself. About your mind. After all, it's advanced enough.
Why do you think people commit suicide? Their emotions took them on a ride.
Down the wrong track.