The scariest shiiiit I ever experienced was during my sleep. If anyone ever experienced this, they'll tell u it scares the living hell outta u. Ur in bed sleeping away, then all the sudden it feels like someone is holding u down by ur chest and u would try screaming but nothing would come out of ur mouth. You want to move so bad but you cant, it's like your body is possessed. And you even get the feeling that ur body is levitating/floating. Ur brain is awake so you feel these sensations but your body is asleep so u cant control ur movement or yell for help. I experienced this twice, but thankfully there is a scientific explanation for this. It is called Sleep Paralysis.