I realized that no one ever taught me that there were monsters coming into my bedroom at night

At least, that you can remember. I had recurring nightmares about the chase scene from The Shining during my childhood and adolescence even though I’d never seen it, then saw the film again as a teen and it all made sense. I can only assume I watched it with my dad at a point when I was still young enough that I wasn’t forming long-term memories, so that terror hung out in my subconscious.