As a child, I had terrible insomnia and was a little afraid of the dark. I was very fearful of demons. Now I know it is all nonsense, but I still struggle with chronic social anxiety and frequent insomnia. I have gotten a good deal of relief through therapy and anti-depressants, though.
The Great Tribulation was not as scary an idea (oddly enough) as was demonization. I was truly frightened of that. I often hid under my blankets and suppressed my breathing to "hide" from demons at night. It's a wonder I didn't suffocate.
I was also very afraid of getting caught masturbating, LOL! That was a huge worry cuz I did it a lot.