As is the case with pretty much every book-to-film adaptation, Stanley Kubrick’s 1980 horror film The Shining left out things that were present in Stephen King’s original 1977 novel. So when it came time to adapt Doctor Sleep, Stephen King’s sequel novel to The Shining, for the big screen, director Mike Flanagan saw a unique opportunity. Specifically, Doctor Sleep will include parts of The Shining that didn’t make it into Kubrick’s movie. In Flanagan's own words,
My strategy was to honor what Kubrick did, and to approach this like an authentic sequel to the film that he made, while also trying to honor themes from the novel The Shining that didn’t make it into the film.
Although The Shining didn’t have a sequel novel in 1980 (Doctor Sleep was first published in 2013) and Stanley Kubrick is no longer around to direct the follow-up film, Mike Flanagan approached Doctor Sleep as a true continuation of that legendary director’s classic movie. He wanted it to feel of a piece of Kubrick’s The Shining in his adaptation, but also wanted to address certain things that were missing from Stephen King's source material.
As he explains in a new featurette for Doctor Sleep, Mike Flanagan wanted to incorporate the themes from Stephen King’s novel that were not present in Stanley Kubrick’s adaptation. As a sequel, Doctor Sleep afforded him this opportunity. That being said, Flanagan does not explicitly say what he is bringing from the original into the sequel, so we’ll just have to see it to find out.
This is likely more incentive for fans of Stephen King’s novel to see Doctor Sleep, because it provides an opportunity to see themes of the story that were previously lost in translation or changed in the Kubrick film. There are always going to be differences with adaptations, and it's common to watch an adaptation of a beloved book and cringe in frustration when something we cherish from the source material was left out or adapted poorly.
That is the tight rope Mike Flanagan had to walk with Doctor Sleep. He wanted to honor Stanley Kubrick’s cinematic classic, while also doing right by his hero, Stephen King. To do that he embraced King’s novels and their characters, stories and themes, while still committing to the significant changes made by Kubrick and his fellow filmmakers in the making of the 1980 version.
Just as the director of a television pilot establishes the tone and aesthetic of the series to which predecessors can adhere, Mike Flanagan made sure that he made Doctor Sleep in the style of Stanley Kubrick, using the cinematic language of that original movie, as well as significant elements of the production. A big part of that was bringing back The Overlook Hotel for Doctor Sleep. So you should be able to watch the two movies back to back and feel like they fit together, which is pretty cool.