Researchers believe that three core elements influence the kind of fear I'm talking about: disturbing images, a lack of control, and a perception of imminent fear.
When it comes to scary Halloween scenes like those from TV and movies, these should be defined as "fake fear"; you're not under actual threat yourself. However, that doesn't stop your body from thinking you are.
A thing in your brain called the amygdala is triggered here. This is the part of our lower brains that, as neanderthals, would have helped us get away from an angry wooly mammoth.
You've probably heard of the "fight or flight" response before: this is kicked off by the amygdala as hormones surge through your body, and it's also connected to your hippocampus, which stores your memories and will remind you to feel fear again in the future.
When we're scared, the amygdala isn't telling us what or how to think. It controls our reaction to threat, and it struggles to differentiate between "real" threats and "fake" ones. Moreover, every previous time you've been scared may be subconsciously tapped into by your hippocampus, almost as if you have PTSD.
So when that burn of fear is crawling over your body whilst watching Making a Murderer, or you jump up when vigilantes make surprise visits in The Purge, your brain is remembering past feelings of being scared all over again. They could be memories of being chased in the schoolyard, or watching the original It for the first time.
The feeling of fear, as an emotion, is one of the most powerful and long lasting. It can make an impact for days, weeks, months, and years after an experience. Unfortunately, your brain lacks the true ability to tell yourself, "there's nothing to be afraid of".
This is often mentioned in discussion of the effect on society-at-large of the 1975 film Jaws: just think of how many people are afraid of the water because of a movie, even though it poses them no real danger.
There's also another good reason why our bodies feel scared when watching movies like those mentioned. This is something horror filmmakers tap into every time, almost without fail. It's the banal setting of suburbia. AKA where most of us live.
Inserting unrealistic scares into situations we are very familiar with in daily life (taking a shower, going to school, walking on a quiet footpath...) helps to bundle up the way your amygdala and hippocampus entice anxiety.
The resulting experience when you feel afraid, whilst presented with a scenario familiar to real life, is a compounding dichotomy of familiarity and impossibility. It's a feeling of "it could happen to me" that you struggle to shake off.
Granted, lots of things that scare us on the small screen aren't well-known to our realities at all. I've certainly never been to an asylum or a spaceship, but that doesn't stop me fearing the murderous nurses of American Horror Story or the alien from Alien.
Nevertheless, after spending the month of October indulging in horror from the comfort of my living room, I think everything I see now scares me a little less.
It feels almost like exposure therapy that's evolving my brain. As if I'm being conditioned, perhaps, that "there's nothing to be afraid of" after all.
