Halloween—the season of costumes and candy, jack-o-lanterns and haunted houses—is nearly upon us. Everywhere you look, someone is trying to rustle up a good scare. The “Thriller” video will no doubt get a bump in views on YouTube. Frankenstein and Dracula will be repeated on cable until Thanksgiving, and horror-movie fans are gearing up for a fresh round of frightening flicks to hit the big screen. Zombies, blood, chain saws, creepy music—oh, my!

Why do some of us love to be terrified by movies? Simply put, it’s the thrill. Getting scared delivers the same kind of adrenaline rush that people get from activities like skydiving or surfing, experts say. A recent German study found that when people watched menacing moving scenes, brain scans showed the areas involved in both physical and psychological arousal were activated.

For those of us hard-wired to seek thrills, getting them from a movie is certainly safer than jumping out of a plane. But the very ability of these images to convince your brain that something real and terrifying is happening can make scary experiences a negative psychological event for some people—especially children.

“Most of us have a fright reaction that’s very similar to what we’d have in a scary situation in real life,” explains Joanne Cantor, Ph.D., professor emerita at the University of Wisconsin-Madison and president of Your Mind on Media. Your nervous system gets all revved up; adrenaline is released, your heart rate and blood pressure go up, your palms get sweaty and your muscles tense, all of which put you on the edge of your seat. “On some level, the brain can recognize the difference between what’s happening onscreen and what’s happening in real life,” says Cantor, “but the lower levels of the brain—especially the amygdala—act in a way that doesn’t distinguish.” Even though we know intellectually there is no real danger, our fight-or-flight response still gets activated, which gives the thrill seekers among us a buzz to love.

Meanwhile, when a character onscreen looks terrified as a gruesome ax-wielding psycho chases her through an attic, the mirror neurons in your brain get triggered, which can make you feel almost as terrified as if you were being chased with an ax. In addition, the way a story unfolds can also affect your reaction in surprising ways, through a process called “transfer of arousal.” If you’re primed with fear while watching that horror flick, and there’s a happy ending as the heroine escapes from the clutches of the ax-wielding maniac, you’ll experience your next emotion (such as relief or euphoria) even more intensely than you would have if you hadn’t felt scared out of your wits earlier, explains Glenn Sparks, Ph.D., a media effects researcher and professor of communication at Purdue University. In other words, the first powerful emotion you feel heightens the intensity of the one that follows.

So enjoy ’em if you like ’em. But horror movies aren’t fun for everybody. Some people feel deeply disturbed by horror movies, which can actually result in enduring effects like anxiety, insomnia, bad dreams or even changes in your behavior (like staying out of the attic). “These films can induce very intense emotional reactions that tend to linger after the films are over,” says Sparks. After all, what child of th ’80s didn’t think twice about becoming a camp counselor after Friday the 13th?

To investigate this point, Cantor had 530 students at the University of Wisconsin-Madison write about their exposure to scary movies or TV shows before they were age 14 and how it affected them in the long term. She found that 58 percent experienced enduring sleep disturbances after seeing those frightening screen scenes and 58 percent began avoiding specific situations, like swimming or being alone. “Kids can literally be traumatized by a movie and it can be very hard for them to get over this fear,” Cantor says. Until it’s been firmly established that your child doesn’t experience these negative side effects, it may be wise to downplay the fright-fest side of Halloween; it’s also wise to vet the content of scary movies before letting your child watch them, Cantor says.

When it comes to your own viewing pleasure (or horror), treat yourself to a frightening flick if you enjoy a good scare. If not, don’t be afraid to speak up about your preference. “A lot of women watch scary movies not because that would be their first choice but because it’s the man in their life’s choice,” Cantor says. “If you know you don’t sleep well after watching a scary movie, lobby for something else.” But if you aren’t bothered by lingering effects, go ahead and enjoy the emotional ride and the euphoric aftermath.