You should definitely read The Shining before picking up Dr. Sleep. This is because Dr. Sleep is a direct sequel to The Shining, and it heavily relies on the events and characters introduced in the first book.
Reading The Shining will give you a deep understanding of Danny Torrance's past, his psychic abilities, and the trauma he experienced at the Overlook Hotel. This background information will enhance your enjoyment of Dr. Sleep, as you'll be able to connect with Danny on a deeper level and appreciate the complexities of his journey as an adult.
Dr. Sleep is a standalone novel, meaning you can read it without having read The Shining, but doing so will significantly diminish the impact of the story. You'll miss out on crucial backstory and thematic connections, making the reading experience less satisfying.
While The Shining is the only essential prerequisite for reading Dr. Sleep, you may also find it beneficial to read other Stephen King novels, such as It or Misery, as they deal with themes of trauma, childhood, and the supernatural, which are also prominent in Dr. Sleep.
