Hereditary. V/H/S. Raw. The last few years of horror films have gotten scarier, gorier, and more intertwined with frightening current events than ever before. They’ve caused viewers to scream, jump, experience racing hearts, and even throw up. I mean, there are a lot of creepy things that happen to your body when you watch a scary movie.
At the Toronto Film Festival screening of Raw, a movie that features some pretty graphic cannibalism, The Guardian reported that paramedics had to be called because moviegoers were fainting. The 2012 release of V/H/S caused fainting incidents at Sundance and later in a theater in Los Angeles, too, noted Gizmodo.
When Hereditary was first released, the company behind the film, called A24, held special screenings where moviegoers were asked to record their heart rates during the movie using the health app on their Apple Watches. As Buzzfeed News reported, viewers had recorded heart rates as high as 164 beats per minute, which is pretty high for a healthy adult who isn’t exercising at the moment.
While this “heart rate challenge” was just a marketing move for the film, it showed that watching scary movies can actually affect the human body. And those effects aren’t limited to a racing heart. Even if horror flicks don’t cause you to pass out, your body is still reacting to what you’re seeing — in ways you may not even realize.
1. Your Fight-Or-Flight Response Is Triggered
Dr. Katherine Brownlowe, MD, psychiatrist at The Ohio State University’s Wexner Medical Center wrote that watching a scary movie causes the body to respond by going into fight-or-flight mode without the viewer even realizing it. It starts with stress hormones flooding the brain.
“They allow the body to continue in this ‘fight-or-flight’ status for as long as possible. When you hear of people performing incredible feats of strength in crisis, like lifting a car off an injured person, thank cortisol and adrenaline for that."
2. Your Heart Races, & You May Even Burn Some Calories.
Those stress hormones get your body ready to either fight for your life or make a break for it, and to do that, your body directs blood and oxygen out to the muscles by pumping harder and faster.
Grunge.com cited one study where horror film viewers’ heart rates increased by 25.3 percent on average, as though they were engaging in light exercise. They also burned approximately 113 calories per viewing. The movies that caused hearts to race the fastest? The Shining, The Exorcist, and A Nightmare on Elm Street, of course.
3. You Get Eerily Still
Re: predators, Brownlowe noted that freezing in place makes prey less visible to them. Just like the girl hiding in the closet onscreen, you may feel yourself tense up and freeze in your theater seat while her killer searches the room, and your body tries to make it seem like there’s nothing to see here, move along, thank you very much. That tension also preps your body to make a sudden move if needed.
4. Your Senses Are Heightened
When you feel like prey, your body responds like there’s a real predator in the room, not just on the big screen. This means your senses may be sharper than usual — your hearing will become more sensitive, and your vision will perceive colors as being brighter than usual, wrote Brownlowe. As your mind hones in on all the sensory details of your environment, it's getting you ready to spot a threat and make a break for it.
5. You Might Get Nauseous Or Need To, Well, Excuse Yourself To The Restroom
Centuries ago, when early humans were constantly threatened by predators, this kind of reaction might have helped them make a quicker escape. If you feel some bowel pressure coming on, or maybe an intense bout of nausea, your body may be smashing the ‘purge system’ button to get rid of excess waste and run away, according to Brownlowe. Or, gory movies may just not be your thing.
6. Your Immune System Works Harder
A study from Coventry University compared the amount of white blood cells levels of a normal, not-totally-frightened control group to the levels of a group watching The Texas Chainsaw Massacre for the first time. After watching the movie, viewers had more white blood cells in their blood, higher blood pressure, and higher hemoglobin concentrations, which suggests the immune system is in overdrive trying to protect your body while stressed.
7. You Actually Leave Feeling… Pretty Good?
Brownlowe explained that dopamine is released as the brain comes down from all those stress hormones, which of course feels warm and fuzzy after an hour and a half of fear. But for some people, experiencing a sense of risk actually improves their outlook on their own lives.
“There is a psychological benefit to experiencing something that seems scary or risky and then coming out the other end safe and well,” she wrote. “It challenges our beliefs about risk and, in some ways, can ‘reset the thermostat’ for people so that things that had seemed intimidating may be easier to deal with in the future. After watching two hours of a Halloween scare-fest, it’s not as worrisome to ask your boss for a raise, face a budget shortfall, or prepare to give a public speech.”