Humans and Health

Science of Fear: What Happens When You’re Afraid?

Megan Cuerden

When you think about it, what is it that gets you really scared? For me, it’s always been that scene in Harry Potter with the insane number of spiders. Paranormal activity can send me off to sleep like a lullaby, but one small spider and I’m off running for the hills.

Everyone has felt fear at some point in their life, and what’s unique about it is that there are so many different ways to feel fear, and everyone has a completely individual experience. Whether you’re scared of public speaking, claustrophobic or even have arachibutyrophobia (fear of peanut butter)!

We all know the classic symptoms, the racing heart, breathlessness, trembling hands. So why does all that happen?

It is adrenaline that kicks off that all too common fight or flight response

The notion of fear is rooted in a part of the brain called the amygdala. The amygdalae are clusters of neurons responsible for emotion and the reaction to emotion from the rest of your body. These clusters sit within the temporal lobe of the brain, connected to the hippocampus—the centre responsible for memory—which means the amygdalae can stimulate our bodies to become afraid when we come across a threat we’ve encountered before.

The activation of the amygdala stimulates the production of a multitude of hormones, such as adrenaline (epinephrine) and the sympathetic nervous system. It is adrenaline that kicks off that all too common fight or flight response. It’s activated in times of excitement as well as times of fear, depending on the context as to whether your body will feel good or bad about it.

Even when we fear something entirely unrealistic or that we know won’t happen (such as an entire horde of giant spiders coming to try and eat you) the conscious part of the brain, the forebrain, is unable to stop the physiological reaction from occurring, which may seem strange, but during evolution the amygdala came first—probably to protect us from actual predators—and now it’s a deep rooted part of all of us.

However, our brain can still slightly differentiate between types of fear. The response to watching a scary film for example, is called manufactured fear, which is obviously going to feel pretty different to genuine fear. The hippocampus and prefrontal cortex come into play here, helping the amygdala to understand the potential threat.

Organs that aren’t deemed necessary for survival will being to slow down

Adrenaline is the cause of many of the effects of being scared, it causes our bronchi to dilate and our breathing rate to increase which causes that rapid heart rate and high blood pressure. These are all coping mechanisms, and there are many other presentations too, like goosebumps, cold sweats and crying.

As well as the obvious stuff we’ve all noticed before there’s a lot of secret changes that occur when you’re scared that you don’t even notice—even your pupils dilate! Organs that aren’t deemed necessary for survival will being to slow down, such as the gastrointestinal system. The blood flow and movement of glucose to the skeletal muscles will increase—quite literally preparing for you to either fight or flight.

Generally, once the threat or perception of threat has dissipated, you’ll probably feel pretty knackered. This happens as the adrenaline levels reduce and you come to the end of that boost of energy plus, being scared is just pretty tiring!

So, whether you’re a Hocus Pocus lover, or a complete novice to anything spooky, maybe keep a light on when you go to bed this Halloween.

Megan Cuerden

Photo by Anthony from Pexels. Image licence found here. No changes made to this image.

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