There are two types of people: those who hate horror movies, because they're scary, and those who love horror movies... because they're scary. You can hardly blame those who avoid horror movies like the plague, because researchers have found that what goes on in your brain when you're watching one is remarkably similar to what goes on in your brain when you're about to go out like our girl Drew Barrymore up there. RIP. Turns out fear has the same chemical make-up, regardless of whether you're in actual danger or not, says the episode of Reactions above.

But what exactly is fear? At the most basic level, fear is a cognitive response to a threat that sets in motion a bunch of chemical processes that gear our bodies up to remove ourselves from danger. Our central nervous system is the first to respond, and it sends a signal to a region in the brain called the thalamus, which then passes this on to the amygdala via a neurotransmitter called glutamate.

The glutamate is also responsible for transmitting fear signals to the hypothalamus and the periaqueductal grey. Also known as the central grey, the periaqueductal grey is involved in our response to things like pain, fear, and anxiety, and when it's activated, it sends you into a state of hyper-alertness in an effort to get you ready to flee. The hypothalamus, on the other hand, is responsible for helping you decide between 'fight' or 'flight', and kickstarts the production of the hormone adrenaline, which is handy regardless of whether you're running away or sticking around to defend yourself.

As the video explains, the release of adrenaline also kicks another major organ into gear - your liver, which will start producing a bunch of glucose that will give you an extra jolt of energy once it hits the bloodstream. The steroid hormone, cortisol, is also produced, and its role is to keep all of these 'fight or flight' responses up and running.

But what if neither of these responses end up getting you out of danger? At some point, you're probably going to release a blood-curdling scream, and it's called that for good reason. Research suggests that we perceive screams in a completely different part of the brain than other human vocalisastions. While language is perceived by the brain's temporal lobe, screams go directly to the amygdala, where our fear response is processed. This means that whether you're making the scream or just hearing it, your brain's response will be remarkably similar.

And here's when things get grim: what happens if you really don't get away from whatever axe-wielding maniac is trying to get you? I'll let the Reactions team handle that one, but let's just say there really is a chemical basis to clichés about 'seeing a light' and having your whole life flash before your eyes. Be safe out there this Halloween, your poor old brain will thank you.