Stephen King Fans discussion

Looking for a recommendation of a good Stephen King novel with a specific theme (I’ll even take Novellas or Short Stories):

I’m currently in the middle of Bag of Bones (don’t spoil it just yet!) and really like the idea of the narrator being unsure of what he’s experiencing. It reminds me a lot of The Shining where the main character slowly descends into madness. I’m sure with a career as long as King’s, these aren’t the only two novels where the main character slowly goes mad (and you the reader aren’t quite sure if you should follow him down or stay above it all and watch him lose everything.)

I have a feeling Insomnia is probably my best bet for something along these lines, but if there are other recommendations, I’d love to hear them!

Thanks in advance.

Gerald's Game gets trippy and psychological. It starts to get hard to see what is real.

I would suggest 1922; novella in Full Dark No Stars that has the vibe you are looking for.
Insomnia is a hard one that's connected to the Dark Tower.
The Dead Zone doesn't have the madness but the story is in his top 10. The number one best is either IT or The Stand; your choice.

Thanks for the feedback! Got some good books to check out soon :)

Two Past Midnight: Secret Window, Secret Garden and The Dark Half are more along the lines of what you are looking for.