Have you been sleeping well? If so, that might be about to change. It was announced on Friday that Room 237 director Rodney Ascher‘s new documentary The Nightmare will be released in theaters on June 5. The film concerns sleep paralysis, a condition in which people dream they are visited by terrifying shadowy figures.

According to co-producer Tim Kirk, it initially proved difficult to find interviewees, but once word got around about the project, the pair were overwhelmed with sleep paralysis sufferers who wanted to talk about the condition. “We reached out through Reddit and Facebook and suddenly people were coming to us,” the producer told EW at least week’s Stanley Film Festival, which screened both The Nightmare and Kirk’s directorial debut, Director’s Commentary: Terror of Frankenstein.

In addition to interviewing victims of sleep paralysis, The Nightmare also features dramatizations of their nightmares, with actors portraying the sufferers. “What was really great was Forrest, who is one of the [interviewees], he actually visited the set and met ‘Forrest'” says Kirk. “He was there for the Bay of Fundy sequence which was this crazy experience—sort of half-dream, half-reality—that changed his life. So, that was really strange for him to be on set and experiencing that.”

You can see the trailer for The Nightmare, below.