Fan Casting Plagued by Nightmares in Sort by Tropes

A character may be suffering from trauma or from the supernatural. They may be dreaming of the same thing every night or having a variety of them. They may never explain what these nightmares are about, or we'll get a full description of them. They may even result in the character becoming a willing insomniac. What stays consistent is that the nightmares don't stop. They affect the character on a consistent or near-consistent basis, and act as a sign of some psychological issues or things outside of their control. Even if the audience isn't sure what the issue is, it's obvious that the character is suffering and has something very wrong with them.