If there are few things less interesting than hearing other people talk about their dreams, then director Rodney Ascher has pulled off something uniquely impressive, if still somewhat overstretched, in “The Nightmare,” an intriguing documentary-horror hybrid centered around the experiences of eight individuals who have suffered from the mysterious phenomenon of sleep paralysis. Mixing talking heads, surreal bedtime re-creations and shamelessly assaultive scare tactics, Ascher’s playful, visually inventive sophomore feature isn’t at the same level as “Room 237,” his brilliant 2012 inquiry into the mystique of Stanley Kubrick’s “The Shining.” But it shares with its predecessor a warped affection for eccentric storytellers and a desire to give vivid cinematic form to their darkest imaginings, if that is indeed what they are.

World premiered as a midnight entry at Sundance, “The Nightmare” won’t be any independent distributor’s idea of a commercial dream, but could amass a following on the fest circuit and as a specialty theatrical/VOD pick, if marketed with an emphasis on its more overt horror elements. At one point, the movie cheekily suggests that simply describing your night terrors to someone might be enough to ensure that they start experiencing them as well; Ascher’s film could conceivably benefit from a similar word-of-mouth domino effect, given the unusual prevalence of sleep paralysis (full disclosure: this critic is no stranger to it himself) and the wealth of online blog posts, videos and forums devoted to the topic.

As described by all eight camera subjects (identified here by first name and last initial), the condition is one that seems to suspend the sleeper in a not-quite-dream state, in which they are awake and cognizant of their surroundings, but otherwise completely immobilized — a feeling that has led some to wonder if they’re having an out-of-body experience, or suffering a panic attack, a stroke or the initial throes of death. That premise established, however, the tales become very different and in some cases a whole lot weirder, as individuals describe not only awakening to find themselves stiff as a board, but also bearing witness to all manner of ghostly intruders which they are then unable to physically ward off.

Los Angeles resident Forrest B. recalls early childhood visions of two smiling, big-eyed, alien-like creatures approaching his crib. Korinne W., from Covington, Ky., says she remembers her small plug-in nightlight somehow tinting her entire room an ominous shade of red. The most commonly reported visitations involve black silhouetted figures referred to here as “shadow men,” who loom over their victims lying helpless in bed. Other accounts play like spooky variations on this theme: New Yorker Chris C. recalls seeing a towering red-eyed giant, whispering “You are going to die” — a vision that was all the creepier for mirroring a similar vision experienced by his girlfriend as she slept beside him. At one point, a common theme of sexual violence begins to emerge. One woman describes sensing that she was being raped by some evil being, bringing Barbara Hershey’s ordeal in “The Entity” (1982) to mind; a man recalls waking up in a cold sweat after suffering a castration nightmare, while another describes a bizarre vision rooted in adolescent sexual panic.

All these demons are conjured onscreen in nighttime re-enactments in which the paralyzed subjects (played by actors) are terrorized by some combination of dark-robed extras and/or sparely deployed visual effects — i.e., a spider suddenly jumping onto the screen in skin-crawling closeup, to cite but one of the film’s many admittedly cheap but effective scares (accentuated by Jonathan Snipes’ disquieting music and sound design). Those jolts aside, Ascher’s film is less an outright scarefest than an eerie immersion in a nocturnal dreamscape, one where the various intruders we see are almost deliberately stylized in such a way as to suggest they’re mere figments of the imagination. (One cleverly designed sequence, in which we see a shadow man leave one bedroom, cross a hallway and enter another bedroom, resembles something out of a live-action, adult-skewing “Monsters, Inc.”)

It’s no surprise to learn that Ascher was inspired to make the film by his own bouts of sleep paralysis, a fact he tacitly acknowledges by sometimes appearing on camera while interviewing his subjects. (The moodily underlit cinematography is by Bridger Nielson.) Ascher edits “The Nightmare” in a roving, almost circular fashion, moving from one interviewee to the next as they recount their specific terrors, then starting all over again, and allowing them to deepen and elaborate on their stories in different ways. Despite its repetitive structure which could conceivably have worked just as well in a shorter format, the film impresses to the degree that it sustains such a seemingly narrow topic of inquiry over the course of its 90-minute running time. For a movie not entirely set within the waking world, it’s never somnambulant.

Ascher has no real interest in explaining, demystifying or debunking its subject; the significant amount of research that has been done on sleep paralysis is acknowledged, but never really delved into. What excites him, as in “Room 237,” is the chance to assemble a vivid collection of smart, friendly, slightly unhinged voices and following them to the brink of their obsessions and beyond. To that end, he seems less interested in the causes of sleep paralysis than in its effects on the psyche and even the soul: Chris, who has sought any number of forms of professional treatment, claims that he stopped being an atheist after one particularly vivid attack, while Connie Y., from Costa Mesa, Calif., describes how her sleep paralysis enabled her conversion to Christianity — and have left her alone ever since.

Just as “Room 237” reveled in the crazy dissertations on Kubrick’s work that have proliferated in a Web-enabled fan culture, so “The Nightmare” shows how the Internet has enabled the rise of an apparent sleep-paralysis cottage industry, where the legions who have wrestled with it worldwide can share stories, swap tips and generally contribute to each other’s paranoia. Ascher is particularly fascinated by the hold that movies maintain on the popular imagination in this regard: Excerpted films here include “A Nightmare on Elm Street,” “Jacob’s Ladder,” “Natural Born Killers” and the largely forgotten 1989 Christopher Walken alien thriller “Communion” — all of which deal in imagery similar to what his subjects have seen in their visions. Whether it is the movies that have shaped our dreams or our dreams that have shaped the movies, it’s safe to assume that “The Nightmare” will find its place in that eternally recurring cycle.