I don’t know if you remember this old horror movie, but we were living in California in 1959 or 60 when “Thirteen Ghosts” came out. I was 8 years old and that movie gave me nightmares for WEEKS!
I’ve seen a later version of that movie several times on SyFy. I didn’t know there was an earlier version. That’s one creepy movie and I watch it every time I know it’s on.
Seeing it at such a young age WOULD give a kid nightmares for a while.
“The Mummy”, with Boris Karloff, gave me nightmares for weeks when I was a kid. I grew up on horror movies and it was hard to scare me, but that one sure did.