Have you ever experienced real horror? That’s what a taxi driver said to me. It was in the wee hours after a horror film festival. As he told me about his cousin, an Afghan chief, I expected it to be my last night on earth. It wasn’t (obviously). Real life can often be much more terrifying than fiction. Anyone who’s ever experienced sleep paralysis will understand this. It’s an incredibly scary experience and something you’d not wish on your worst enemy.

Sleep paralysis is a phenomenon where a person either falling asleep or in the process of waking up is unable to move, speak or react. That’s a terrible thought in itself but it’s often accompanied by extremely vivid hallucinations. In Rodney Ascher’s (himself a sufferer) documentary, The Nightmare, he interviews eight people who suffer from the condition. He augments these segments by recreating their experiencing, meshing the traditional documentary format with a darker horror aspect.

On the one hand, The Nightmare is an insightful investigation into a truly terrifying condition which afflicts many people. On the other, the reconstructions feel more like something from a horror film. Ascher argues that many of the most famous genre tropes are a result of their creator’s sleep paralysis. Putting them on screen, in films like A Nightmare on Elm Street or Insidious, perpetuates the condition for a whole new generation of people. At times, The Nightmare manages to play this genre blurring brilliant;y, providing jolts and scares, but it can get pretty repetitive after a while.

The Nightmare is released on DVD by Altitude Films and is out now.