What fear is oneirophobia?

Oneirophobia is the fear of dreams.

The term comes from Greek: "oneiro" is "dream" while "phobos" means "fear."

Frightening dreams (aka nightmares or night terrors) may cause sufferers to avoid sleep. The condition may particularly afflict those with PTSD (post-traumatic stress disorder) where dreams can represent the re-experiencing of trauma. A flow-on effect can be self-medication with drugs or alcohol.

https://en.wikipedia.org/wiki/Oneirophobia