Fear of the unknown

Misplacements, distorcion, confusion.

The obscurity.
Your mind always tries to associate something that isn't sure of what it is, to something alike, yet if your mood is frightened, it can often be associated with horrors, demons, which cause even more fear.

Only strong minds can think more logically and seperate the two things, but its hard when your brain can't regonize a object, as your brain gets stressed, or this moods affect you it gets harder and harder, and the horror starts.
Not to mention that strong minds normally have more imagination, which means more associations with darkness and horrors are possible.

Panic is when such things like this happen, but normally at a very fast rate, you lose the control of your own mind, and you are at horror's mercy, that weakness leads you to do things unwanted, mostly to escape from that place, even though you normally don't pick the best way out because you are not able to think, you just want scream your way out of it, no matter what.

"Time to run, time to scream, time to die..."