Horror movies affect everyone differently. Some people can sit through an entire marathon and it's no big deal, while others will be left with some very real feelings of fear and distress. While horror movies are made to scare you, there should be some comfort in the fact that the images you see on screen aren't real. So why do scary movies still give some people nightmares? According to a therapist and a dream expert, there are a couple of theories to explain why.

Nightmares are terrifying dreams that can wake you up and keep you awake the rest of the night. They usually occur in in the later hours of rapid eye movement sleep. According to the National Sleep Foundation, it's more common in children, but about 50% of adults still get nightmares too.

There are many different things that can cause nightmares such as eating right before bed, drinking alcohol, and taking certain medications. But stress, anxiety, and trauma, are usually the root causes behind bad dreams. If watching a horror movie makes you feel scared and anxious, it may play out in your dreams as well.

"We're wired to develop some anxiety in response to a threat," Sunny Volano, LPC, licensed therapist who specializes in anxiety, tells Bustle. "While movies are not a real threat, they create the same fear in your brain, and it has trouble telling what's real versus imaginary. Scary movies can cause someone to have nightmares because it triggers the fight or flight response."

According to Volano, it's why people with anxiety or trauma are more prone to getting nightmares. If you're someone who's always slightly on alert, it can make you more sensitive to scary images like blood, gore, and violence. "These images can get stuck in your head and can lead someone with anxiety to feel fearful over what could happen to them or someone they love," she says.

If you don't have anxiety or trauma, there's another reason why you may get a nightmare after watching a horror movie.

It's Your Brain's Way Of Processing Emotions

"Dreams are stories created by our minds to help us express and expel complicated emotions," Pam Muller, dream expert and author, tells Bustle. "In fact, noted dream researcher Ernest Hartmann, M.D. said that dreams contextualize our emotions. It's our biological attempt at learning from our heightened emotional experiences."

When you have a "sudden spike" in an emotional response, like getting scared from a terrifying image on screen, your brain takes note of that experience and sees it as a learning opportunity. After a scary movie, your brain tells itself that there's something here worth paying attention to.

"Nightmares after horror films are our mind's attempt to feel the full extent of the emotions that arose during the screening, specifically emotions that we didn't allow ourselves to fully realize or feel at the time," Muller says. It's your brain's way of working out the scary experience so you can avoid having another negative response like that again in the future.

How To Avoid Getting Nightmares After Watching A Horror Movie

If you're someone who likes the horror genre but hates the effect it has on you, there are some things you can do to avoid getting nightmares. For instance, Muller suggests having a discussion about the movie with someone before you go to bed. Talk about the scariest parts of the film and what you were thinking and feeling as it happened.

"Make a conscious effort to fully express negative emotions so that there's less repressed energy of that negative feeling for your dreams to work with," she says. If you go to bed with less feelings of anxiety and fear, it's less likely to show up in your dream in some way.

Another thing you can do is to watch something funny or lighthearted right before bed. According to Volano, you don't want to end the day with a scary image in your mind. So try reading or watching something else with positive messages and imagery before falling asleep. You can even try watching a scary movie earlier on in the day so that it's not the last big thing you have on your mind.

Horror movies are made to scare you, and some can leave you awake at night. If you're someone who easily gets nightmares because of scary movies, these are some reasons why.

Experts

Sunny Volano, LPC, licensed therapist

Pam Muller, dream expert, author of 33 Ways to Work with Your Dreams