For anyone unfamiliar with the very real sleep disorder, Night Terrors, it can be defined as nightmares that occur in deep, non-REM sleep, in which the sufferer is overcome with extreme feelings of fear. During a night terror, which may last anywhere from five to twenty minutes, the person is still asleep, although the sleeper's eyes may be open. My reason for offering up an explanation for Night Terrors is twofold: (1) I have personally experienced them in the past, and (2) "They," directed by Robert Harmon, is an unsettling horror film that does an applause-worthy job of showing just how truly terrifying Night Terrors are to experience. Harmon and screenwriter Brendan William Hood could definitely use a crash course in how to develop strong characters and stories, but from a visceral standpoint the film powerfully burrows its way underneath your skin.

Julia Lund (Laura Regan) is a graduate student working against a deadline to complete her Psychology thesis. Her stress level raises significantly when she witnesses longtime friend Billy (Jon Abrahams) commit suicide after he erratically warns her that the night terrors they suffered from as children have come back to get them for good. Julia is understandably skeptical at first, but when she and two acquaintances, Sam (Ethan Embry) and Terry (Dagmara Dominczyk), start re-experiencing the violent and horrifying night terrors that plagued them years ago, and seem to be linked by a similar wound on their bodies, their fear for their lives grows.

If a horror movie's primary goal is to frighten and disturb, then "They" works spectacularly well. Director Robert Harmon deftly understands that the scariest things are often those that are mostly unseen, lurking just out of frame or in the moodily lit shadows. The monstrous images he creates, with the aid of some surprisingly plausible special effects and René Ohashi's atmospheric cinematography, are some of the eeriest to find their way to the screen this year. A climactic sequence set on a deserted subway is a near-masterpiece of genuine terror that may also make you jump out of your seat (it did me).

Where "They" loses some of its momentum is in the exposition scenes. Save for protagonist Julia, played with an undeniable freshness by Laura Regan (2001's "Someone Like You"), the rest of the characters are sorely one-dimensional, and the relationships that form between them are slight, at best. As fellow night terror victims, Ethan Embry (2002's "Sweet Home Alabama") and Dagmara Dominczyk (2002's "The Count of Monte Cristo") are quite good—too good to be stuck in such unrewarding roles. Marc Blucas (2002's "We Were Soldiers") rounds out the main cast, steadfastly playing Julia's devoted boyfriend, Paul, who has little more to do than stand around and try to comfort the unhinged Julia.

The staple horror movie formula of having a character going off alone and being terrorized in dark, lonely places in between every scene of dialogue is also too often relied upon, creating a predictable repetitiveness. What lessens the blow, however, are some actual good scares. "They" could have been better on a number of levels, but it is, nonetheless, a shiver-inducing, nerve-rattling ride, with a shockingly grim final scene that may offer up as valid a reason as any for keeping the lights on at bedtime.

©2002 by Dustin Putman