Stephen King had 'sleepless nights' after writing disturbing scene for book being turned into a movie

Stephen King admitted a scene he wrote for his own book was so disturbing, it gave him 'a few sleepless nights'.

The acclaimed author is behind a number of cult classics, many with unsettling scenes that stick with us since that first read - or watch.

Need I remind you of that death in Pet Sematary, or the violence of Henry Bowers in It?

Well, the book behind King's latest adaptation - dystopian movie The Long Walk - featured a scene that kept the 77-year-old awake for nights on end.

The film, directed by The Hunger Games' Francis Lawrence, transports us to a dystopian version of the US, where each year 100 teenage boys are selected for the walk.

It's a challenge unlike any other; they must keep a steady pace of at least three miles per hour for the longest time possible.

If they drop below that speed, then after three warnings they are 'ticketed'. In other words, brutally taken out on the spot by armed soldiers.

In the original book - penned by King as a college freshman - the contestants had to walk at four miles per hour.

But even the King of Horror himself thought that it was too torturous and decided to lower it to three miles per hour for the film.

While walking for three miles an hour continuously could take a major toll on the body, one character in the book dies in a pretty horrific way you don't quite see coming - in the book, at least.

And ahead of The Long Walk's release, the author took to Reddit to answer fans' burning questions - including his plans for retirement.

Warning - the rest of the article contains a major spoiler for The Long Walk. If you've already read the book and know what happens, then proceed...

One curious fan asked: "Hey Stephen. Long time fan. My question is this: when you're writing a book like The Long Walk, are there ever times when you're writing a scene that even you have to put the pen down because it gets too dark?"

King responded: "There was a scene in the book where Gary Barkovitch ripped out his own throat. That gave me a few sleepless nights."

Yikes. We're not surprised!

Barkovitch is depicted as one of the more antagonistic and, perhaps, abrasive participants in The Long Walk.

He’s notorious for taunting and provoking the other boys, often boasting that he will be 'the last one left'. Famous last words...

His incessant cruel remarks and aggressive personality have others fantasizing about murdering him themselves.

Despite his overconfident attitude, Barkovitch eventually breaks down under the immense psychological and physical strain of the Walk.

In the book, his death is particularly brutal and self-inflicted: he goes insane, screams and ultimately tears at himself in a frenzied, self-destructive outburst.

The soldiers then finish him off once he can no longer continue walking.

Whether his death will be quite so brutal in the movie is yet to be seen...

The Long Walk hits theaters on Friday (September 12).