"A great horror movie infects our imaginations. It has us double checking the locked door and peeking under our beds before we turn out the lights, just to make sure there are no signs of Freddy or Michael in sight. And just to be safe, we like to keep our feet underneath the covers at all times.
This is the price that horror fanatics have to pay. Often on a nightly basis.
But body horror movies have a much more invasive affect on their audience. After all, how do you defend against something that's happening inside of you? These types of movies take advantage our all-too-real fears of sickness, death, and mutilation. They don't just have us closing our eyes for fear that Jason is going to jump out in the next frame. Instead, they have us clutching our bodies in self-preservation while we watch the characters suffering on screen."