In the past, Halloween has meant the end of the crop and the start of the dark, cold winter. People know this time of year as the "season of death." The Celts thought that the line between the living and the dead became less clear at this time of year. People thought that the ghosts of the dead came back to earth on the night of Samhain, which happened around October 31.

For Druids, their village would have big fires. As night fell, groups of people dressed in animal skins would meet to make sacrifices to their gods. Over the years, the scary holiday has turned into one of the busiest times of the year for businesses. It's now a time to celebrate fear.

Fear itself is deeply wired into our nature, having evolved to protect our ancestors from threats (to our integrity or existence). Similar to all animals, we often learn fear through our experiences, such as being attacked by an angry dog, or watching someone being attacked by an angry dog. However, an evolutionarily unique and fascinating mechanism through which humans can learn about fear is through instruction – we can learn from the spoken or written word. If a sign says ‘beware of the dog’ then approaching the dog is (more) likely to trigger fear. Making up scary stories was probably a good way for people in the past to teach kids about animals that were dangerous, like bears and wolves. But as we thought about what life and death were all about, our stories started to show how we were coming to terms with ourselves and our inner problems. In a way, the monsters are us; they show the scary side of us. And it's good to know about those demons and be scared of them. A lot of the time, the most important lessons in life can be found in scary stories.

People in our society like to think that they live in a safe and stable place, but we know that bad things still happen. Today, when things are better, we have turned fear into a commodity. You can now get your "frights" in packages that are easy to handle. Being scared can be thrilling (and addicting). We like new things that are different from what we normally do. It's all right, but have you read the directions on the package, please?

The reaction starts in the brain before spreading through the body making adjustments in anticipation of your ‘flight-or-fright’ response. Initiating in the amygdala, this almond-shaped set of nuclei in the temporal lobe of the brain is dedicated to detecting the emotional relevance and importance of stimuli. This primes the motor systems areas involved in our escape mechanisms. It also triggers the sympathetic nervous system and the release of stress hormones. Pupils dilate, the bronchi distend and breathing accelerates. Heart rate and blood pressure rise. Blood flow and stream of glucose to the skeletal muscles increase. Organs not vital in survival, such as the gastrointestinal system, slow down. The hippocampus and prefrontal cortex go into overdrive to help the brain interpret the perceived threat. These centres are involved in a higher-level processing of context, which helps a person know whether a perceived threat is real or not. Your ability to make rational decisions becomes impaired, fear turns off the exploratory and risk-taking functions of your brain so you’re only able to react defensively, preventing you from assessing all your options and making smarter decisions. This is why you should never force someone to make a big decision when they’re afraid or taken off guard; in this moment they aren’t capable of rationally thinking through their options.

Fear is deeply rooted in our minds, so it's not a surprise that it also has something to do with the fact that we are social animals. When we go through scary things with friends, our feelings are easy to share in a good way. The way we feel affects each other. When we can see that something isn't really a danger, we can reframe the experience and enjoy the thrill of it. At that point, we are "in control." So, when you look at your friend at the scary house, you can quickly stop screaming and start laughing. After that, we can get past the original "fight or flight" response and feel satisfied, safe, and more sure of our ability to face the things that scared us at first.

Many things, like social learning, setting, and distraction, can change how we feel afraid, but one thing that all of them have in common is our need to feel in control. It's important to remember that everyone has their own unique ideas about what is scary or fun. This can happen to people who love scary things. It depends on whether your reaction is "modulated by the cortical brain" or not. You can be mentally protected against vampires but still be scared of zombies. In the same way, an event can become predictable if it doesn't stir up your emotional brain enough or if it seems too fake to your thinking cognitive brain. As a clinical scientist, I can believe that taking the blood of fresh young "people" can make you live longer, but I don't find vampires interesting. But I don't understand how I get so excited about scientifically impossible zombies.

All fun aside, the abnormal levels of fear and anxiety experienced by one in four of us leads to more serious distress and dysfunction. For one thing, I know how fear can make it hard to enjoy life. Almost 1 in 10 people have had post-traumatic stress disorder (PTSD), and I was one of them. Phobias, social phobia, generalised anxiety disorder, separation anxiety, PTSD, and obsessive-compulsive disorder are all types of anxiety and fear disorders. These problems usually start when people are young, and if they aren't treated properly, they can last a long time and make it hard to do things. They can also be caused by a stressful event, like in my case. The good news is that we have treatments that work (for some lucky people).

Fear is ultimately linked with superstitions, exercises that can sometimes have a soothing effect, relieving our anxieties about the unknown by giving people a sense of control. This could be why superstitions have remained in our society, being passed from generation to generation, despite our scientific advancement. They are rooted in our prehistoric past when our ancestors could not understand the forces and whims of [the] natural world. By alleviating anxiety, superstition activities such as crossing our fingers can improve performance (and so we might assume our ability to survive). Research shows that repeating statements like “break a leg” or “good luck,” boosts our performance, amplifying our ability to master tasks, which in turn improves performance. At first sight there seems to be few downsides to superstition, quickly knocking on a wooden surface (when commenting that one has been in great health for years) is a small price to pay compared with the potentially devastating consequences of illness. However, research shows that an over-dependence on superstition-driven repeated behaviours can develop into an obsessive-compulsive disorder such as excessive hand washing, ritualized bathing or grooming, checking behaviours, mental rituals, need to repeat activities, re-reading text, hoarding behaviours, etc.

Our monsters teach us a lot about ourselves and have a cool part in making our societies what they are. Monster stories are a good way to see how different cultures have changed over time as people have moved around the world. Zombie stories come from West Africa, vampire stories come from Eastern Europe, and genii stories probably come from the Arabic world. We are always making up new monsters. Recently, films (or Netflix) give us a look into our shared fears and how, by getting over them together (hopefully with a happy finish), we all feel better. Movies these days abound where the human race battles evil robots and malevolent computers. Monsters often arise with the emergence of new technologies. A frequently cited example is the classic 1954 sci-fi film Godzilla (a dinosaur-like monster created by nuclear radiation) as a thinly veiled representation of Japan’s anxiety over the lingering effects of the atomic attacks during World War II?

No matter how much we love or hate being scared, we certainly respect it—we even celebrate it with a holiday at this time of year. Some of the chemicals that cause the panic reaction are also involved in feeling good emotions like joy and happiness. So it makes sense that the state of high alertness we feel during a scary event could also be seen in a better way. But what's the difference between having a "rush" and being scared to death? In the end, we're back to "reading the instructions" about the difference between the fears that haunt our daily lives and the "frights" that come in a package and use the basic parts of our brains for fun.

Even though zombies, vampires, and werewolves are all the rage in Hollywood, it seems like real horror is right in front of your eyes. According to polls, the things we fear most are heights, public speaking, bugs (especially snakes and other scary crawlies), drowning, and needles or bloodletting. The only one that really threatens life is drowning. But when we hear about them, we act as if they are a death sentence. A recent poll asked people what they thought about government corruption and cyberterrorism. Almost two thirds of those people said that corruption in the government was one of their biggest worries.