We’ve all heard of the ‘fight or flight’ response, where your body reacts to stress or danger with a faster heart rate, increased blood pressure and several other physiological changes. But there are some lesser-known symptoms that help keep you alive when danger strikes, and they can be a little bit odd. From holding your breath for longer than you thought possible to shaking like a leaf after a scare, humans come equipped with a built-in survival toolkit. Here are some of the strange, clever and occasionally uncomfortable ways your body can respond to a life-or-death situation. (Picture: Getty Images)
1. Holding your breath
How long do you think you can hold your breath? 30 seconds? A minute? Actually, it might be longer than you expect. Cold water triggers the ‘mammalian diving reflex’, a physical survival response to being immersed in water. It slows your heart rate and redirects oxygen-rich blood to the heart and brain, limiting oxygen consumption by non-essential muscle groups. The diving reflex has been widely studied, and a scientific review by Godek and Freeman, published in 2022, explained that it was first described by British physician Edmund Goodwin back in 1786. They add that the dive response is activated with the immersion of the face, specifically the trigeminal nerve, in water. Other research, such as a 2021 study published in the journal Frontiers in Psychiatry, has found that activating the diver’s reflex can combat anxiety or stress, and you can feel these benefits by plunging your face into a bowl of cold water for 30 seconds. (Picture: Getty Images)
2. Bending time
You know how people talk about ‘time slowing down’ in certain moments? Well, when it comes to life-and-death situations, it’s sort of true. Researchers at the University of Iowa College of Medicine studied this phenomenon and found that out of 101 people who had encountered life-threatening danger, 70% experienced the sensation of time slowing down. Nobody knows exactly why this happens, but there are several theories. One of the most prominent is that the brain speeds up processing in high-pressure situations, making time feel like it’s slowed down. However, other studies, including one published in the research journal PLOS One, suggest that time is only slowed down in individuals’ memory of the event. This is because they remember the moment in greater detail, due to the brain taking on more information when afraid. Either way, the brain is working overtime to help keep you alive. (Picture: Getty Images)
Rehearsing danger
You’ve probably been told before that dreams, along with nightmares, have meanings. Many have experienced that common night terror of being naked on stage, and it’s widely thought to be a signal of something causing stress or anxiety in your waking life. But nightmares may do more than reflect your waking fears – they could actually help combat them. In 2019, university researchers in Switzerland and the US found that bad dreams improved the effectiveness of the brain in reacting to frightening experiences when awake. ‘Dreams may be considered as a real training for our future reactions and may potentially prepare us to face real life dangers,’ commented researcher Lampros Perogamvros. (Picture: Getty Images)
Pupils dilating
Human pupils dilate in the dark to let in more light and help us see better, and the same thing happens when we feel threatened, helping vision temporarily improve and therefore avoid the oncoming threat. A 2016 study published in the Journal of Trauma Stress found that individuals who met the criteria for PTSD showed more pupil dilation when showed threatening stimuli, while a 2004 study published in the International Journal of Psychophysiology found participants’ pupil dilation increased when completing a more complex task, suggesting a link between pupil dilation and mental strain. (Picture: Getty Images)
Blocking out pain
If you become injured in a threatening situation, you might not feel the pain until you’re out of danger, enabling you to fight, run or protect yourself. Dan Baumgardt, from the School of Psychology and Neuroscience at the University of Bristol, recently explained in The Conversation how the brain can ‘switch off’ pain. He says that the periaqueductal grey (PAG), a structure in the middle of the brain, contains neurons whose role is to alter incoming pain signals. He wrote: ‘Ever picked something in the kitchen that you suddenly realise is extremely hot? Sometimes that casserole dish or saucepan descends to the floor, but sometimes we are able to hold on just long enough to transfer it to the stove-top. This action may be underpinned by the PAG shutting off the sensation of clasping something too hot to handle, just long enough to prevent dropping it.’ (Picture: Getty Images)
Shaking uncontrollably
‘Shaking like a leaf’ is a phrase often used to describe people experiencing fear, but it’s not a sign of weakness. According to the Fixel Institute for Neurological Diseases, shaking from fear is all part of an ‘internal alarm system’ to help you react to a threatening situation. Adrenaline is released, increasing heart rate, tightening muscles, and redirecting blood flow from your skin to your larger muscle groups. This flood of energy can make your body tremble because it’s getting ready to move fast. (Picture: Getty Images)
Smelling fear
It’s often said that animals can ‘smell fear’, and while humans can’t consciously identify if someone is afraid just by taking a whiff of their musk, there’s some evidence to suggest that we can detect fear in a person’s sweat. For example, a 2008 study in the journal Nature Proceedings had novice skydivers wear absorbent pads on their first tandem skydive, and then later while running on a treadmill. New participants then smelled each of the sweat samples, and the researchers found that when sniffing the skydiver samples, the amygdala part of the brain was more active than in the group who smelled the treadmill samples. The study concluded that humans can subconsciously detect fear from the smell of sweat. (Picture: Getty Images)Add as preferred source