Nightmare

Overview
Nightmares have a rare chance to happen everytime you try to sleep in minecraft. A cave sound along with a transparent skull "jumpscaring" you will instantly wake you up, you cant sleep until its daytime again, trying to do so will result in a message displaying

"You Cant sleep, the fear stops you from doing so"

Nightmares will sometimes give you a 5 minute hunger, slowness or mining fatigue. They have a 5% chance to happen, but chances can increase depending of your previous activities The only way to decrease the chances is from drinking any potions or not doing any risky situations right before going to bed, Sleeping with lights nearby also works.
 * If you fought a monster 7 minutes ago, the chance increases by 20%
 * If you were in a closed dark place (Ex. a cave) 5 minutes ago, the chance increases by 10%
 * If an adopted pet of yours died, the chances increase to 15%
 * If you've been in the nether/end before, its guaranteed
 * It will also increase depending of your level of Fear