I have these too and I always just thought I was nuts and the only one it happened to. This makes me feel not so alone. My first one was when I was about six I thought there was a snake in my bed. Then they started again when I was a teenager. I saw a black hooded figure like a grim reaper, a little girl with a bonnet walk across my room, a noose hanging from the ceiling, and countless spiders and spiderwebs (I still see those a lot). Sometimes I see these twig-like wiggling worms in my bed. Once I saw a demonic small old woman standing over me like she was yelling but I couldn't hear any noise.
Id like to know why so many people see spiders. I believe it could be just a dream continuing as I'm waking up BC I lucid dream a lot and have a lot of anxiety, but I don't think a spiritual explanation out of the question either.