It’s often said that truth is stranger than fiction, and while that may be accurate in some cases, it’s also true that truth can be a lot scarier than fiction. As creepy as Halloween, The Exorcist, or Psycho may be, the viewer can always take a bit of solace from the fact that, well, it’s all make-believe.

Such is not the case when it comes to non-fiction films, and here are five of the scariest:

The Nightmare (2015): Rodney Ascher, the director of the creepy and controversial Room 237 (well, it’s controversial among film geeks), returns with a novel, eerie, and altogether disconcerting documentary about sleep paralysis. More of a freaky collection of oddly similar anecdotes than a traditional A to B analysis of the malady, The Nightmare may prove to be a bit comforting to those who suffer from paralyzing night terrors, but it may also prove horrifying to those of us who don’t. Either way, just don’t watch it with the lights off.

Cropsey (2009): What begins as a documentary about a Staten Island urban legend gradually transforms into a true crime story that’s as shocking and creepy as any scripted horror film. Filmmakers Josh Zeman and Barbara Brancaccio start out by telling us about local legend “Cropsey,” but also manage to draw some direct connections between fiction and reality once they start poking through ominous forests and abandoned mental asylums.

Jesus Camp (2006): This fascinating and quietly disturbing documentary takes us on a tour of an evangelical Christian summer camp that, frankly speaking, does little more than brainwash children into becoming creepy little parrots who recite precisely what they’re taught. Religious extremism of any stripe can be a sobering thing to witness; doubly so when its purveyors focus on forcing their beliefs upon innocent (and frequently ignorant) minors.

Titicut Follies (1967): This heart-wrenching 1967 exposé of a horrific Massachusetts mental asylum was held up in litigation for years, and was unavailable for public viewing until 1992. Debut feature from celebrated documentarian Frederick Wiseman, the film is named for a “talent show” in which many of the inmates participated, and it still stands as a horrific indictment of America’s mental health facilities. Despite the fact that the film was unavailable for about 25 years, this shocking and terrifying documentary may have had a direct impact on American culture; you simply won’t find any facilities like this one anymore — and for that we should be extremely grateful. [Editor’s note: It is now available on DVD via Wiseman’s company, Zipporah Films.]

The Look of Silence (2014): Few things are as horrifying as a visit with true evil. And we get several of those over the course of this tragic, chilling documentary. Joshua Oppenheimer’s follow-up to the equally fascinating (and Oscar-nominated) The Act of Killing, The Look of Silence features interview segments with several of the men who participated in the Indonesian genocide of 1965 — and who exhibit nothing in the way of remorse, regret, or basic human morality.

Honorable mentions: Room 237 (2012), The Cove (2009), The Act of Killing (2012), Killer Legends (2014), Capturing the Friedmans (2003), Jonestown: The Life and Death of Peoples Temple (2006), Grizzly Man (2005).