** Your body is a incredible machine, always working to keep you safe with automatic defences that kick in without you even thinking.
From a yawn that cools your brain to a sudden twitch before sleep, these reactions are your body’s way of staying strong and balanced.
In this article, we’ll look closely at these natural protectors, uncover how they work with fresh scientific details, and explore a few extra defences to show just how smart your body is.
Yawning: Cooling Your Brain and More
Yawning isn’t just about boredom or tiredness. Its main job is to cool your brain when it gets too warm from stress, heat, or long focus.
Yawning pulls in cooler air and boosts blood flow to lower brain temperature, keeping your thinking sharp.
Moreover, yawning also helps balance oxygen and carbon dioxide levels and may even play a social role, like signalling tiredness to others in a group.
A 2013 study showed yawning regulates brain temperature, especially in hot conditions, by acting like a radiator.[1]
Interestingly, yawning is more frequent in warm weather and less when it’s cold, supporting its cooling role. Staying hydrated and resting well can help your body use yawning effectively.
Sneezing: Your Nose’s Bouncer
Sneezing is your body’s way of kicking out unwanted guests like dust, pollen, germs, or even strong smells from your nose.
This explosive reflex shoots air out at speeds up to 100 mph, clearing your nasal passages to protect your lungs and prevent infections. It’s triggered when irritants tickle the nerves in your nose, signaling your brain to launch a sneeze.
Research confirms sneezing is a vital immune defence, removing harmful particles before they settle.[2]
Sneezing can also spread germs, which is why covering your mouth is key. Keeping your airways healthy with clean air and good hygiene supports this defense.
Morning Stretches: Your Daily Warm-Up
That instinctive stretch when you wake up is your body’s morning prep.
It activates muscles, boosts blood flow after hours of stillness, and loosens joints to prevent injury.
Stretching also releases endorphins, lifting your mood and energy. This reflex, called pandiculation, is seen in animals too, showing it’s a deep-rooted survival trait to ready the body for action.
Studies show stretching improves circulation and muscle flexibility, reducing strain risk.[3]
Regular stretching can also lower muscle tension from stress, helping you feel more alert and ready for the day.
Hiccups: A Quirky Digestive Fix
Hiccups are those annoying spasms when your diaphragm contracts suddenly, often from eating too fast, swallowing big bites, or drinking fizzy liquids.
The vagus nerve, which links your brain to your stomach, gets irritated, causing the diaphragm to jerk and produce that “hic” sound.
They might help release trapped air or reset digestion, though their exact purpose is still a bit of a mystery.
Medical research links hiccups to nerve irritation, often resolving on their own.[4]
Chronic hiccups, lasting days, can signal issues like acid reflux, so slow eating and smaller meals can help keep them rare.
Hypnic Jerks: Your Sleep Safety Switch
Ever feel a jolt just as you’re drifting off?
These “hypnic jerks” happen when your brain misreads your slowing breath and relaxed muscles as a fall or threat, firing a quick muscle twitch to snap you awake. They’re most common during the shift from wakefulness to light sleep and can be triggered by stress, caffeine, or fatigue.
About 70% of people experience these harmless jerks, tied to the nervous system’s transition to sleep.[5]
Research suggests they may echo an ancient reflex to prevent falling from trees. Calming bedtime routines can reduce their frequency.
Wrinkled Skin in Water: Built-In Grips
When your fingers and toes wrinkle in water, it’s not just soaking. It’s your body adapting to wet conditions.
The wrinkles, caused by blood vessels shrinking under the skin, act like tiny channels to drain water and improve grip, much like tire treads on a rainy road. This helps you hold onto slippery surfaces better.
A 2013 study found wrinkled fingers handle wet objects faster and more securely than smooth ones.[6]
This trait likely evolved to help our ancestors navigate wet environments, showing how clever our bodies are.
Goosebumps: Your Heat-Trapping Shield
Goosebumps pop up when you’re cold, scared, or emotional, causing tiny muscles to raise your hairs.
This traps air to create a warm layer, helping you stay cozy in chilly conditions. They also tie to hair follicle health, supporting warmth over time.
Emotional goosebumps, like from music, may strengthen social bonds by syncing reactions in groups.
A 2020 study showed goosebumps activate stem cells for hair growth, aiding long-term insulation.[7]
This dual role makes goosebumps a versatile defender against cold and stress.
Tears: Protecting Eyes and Easing Emotions
Tears do double duty: they shield your eyes by washing away dirt, germs, or debris, and emotional tears help you cope with stress or pain.
Crying releases chemicals like oxytocin, which can calm you down and ease emotional overload. It’s like your body’s way of hitting the reset button during tough moments.
Research suggests emotional tears lower stress hormones, offering relief.[8]
Reflex tears, triggered by irritants like smoke, keep your eyes clear and healthy, showing tears are both physical and emotional protectors.
Memory Suppression: Guarding Your Mind
After painful or traumatic events, your brain may blur or suppress memories to protect your mental health. This isn’t erasing memories but making them less vivid, helping you cope and move forward. It’s part of how your brain filters overwhelming emotions, though strong memories can still resurface.
Studies on trauma show the brain uses mechanisms like dissociation to soften painful memories.[9]
This process isn’t perfect and varies by person, but it’s a natural shield for your mind’s well-being.
Shivering: Your Body’s Heat Generator
When you’re cold, shivering kicks in; rapid muscle contractions that generate heat to warm you up.
It’s your body’s emergency heater, burning energy to raise your core temperature and protect vital organs.
Shivering can double your heat production, but it’s a sign you need to warm up fast.
Research explains shivering as a thermoregulatory reflex, critical for survival in cold environments.[10]
Wrapping up and staying active in cold weather supports this defense.
Coughing: Your Airway’s Gatekeeper
Coughing is like sneezing for your lungs, forcefully clearing mucus, germs, or irritants from your airways.
It’s triggered by anything from smoke to infections, ensuring your lungs stay open and functional.
Chronic coughing can signal issues, but occasional coughs are a normal defence.
Studies highlight coughing as a protective reflex to maintain clear airways.[11]
Good air quality and hydration help this mechanism work smoothly.
Bottom Line
From yawning to coughing, your body’s defences are a testament to its incredible design, always ready to protect you.
Understanding these natural systems can inspire you to support them with healthy habits like eating well, staying active, and resting enough.
Your body’s got your back; now you can have its too!
References:
1. Gallup, A. C., & Eldakar, O. T. (2013). The thermoregulatory theory of yawning: what we know from over 5 years of research. Frontiers in Neuroscience. Retrieved from https://pmc.ncbi.nlm.nih.gov/articles/PMC3534187/
2. Nonaka, M., et al. (2008). Sneezing reflex and its role in airway defense. Journal of Allergy and Clinical Immunology. Retrieved from https://www.jacionline.org/article/S0091-6749(08)00344-5/fulltext
3. Behm, D. G., & Chaouachi, A. (2011). A review of the acute effects of static and dynamic stretching on performance. European Journal of Applied Physiology. Retrieved from https://link.springer.com/article/10.1007/s00421-011-1879-2
4. Kahrilas, P. J., & Gupta, R. R. (1991). The pathophysiology of hiccups. Gastroenterology Clinics of North America. Retrieved from https://pubmed.ncbi.nlm.nih.gov/1918117/
5. Sleep Foundation. (2025). Hypnic Jerk: Why You Twitch When You Sleep. Retrieved from https://www.sleepfoundation.org/parasomnias/hypnic-jerks
6. Changizi, M. (2013). Science gets a grip on wrinkly fingers. Nature. Retrieved from https://www.nature.com/articles/nature.2013.12175
7. Harvard Health Publishing. (2020). Wondering about goosebumps? Of course you are. Retrieved from https://www.health.harvard.edu/blog/wondering-about-goosebumps-of-course-you-are-2020080320688
8. Gračanin, A., et al. (2014). Why crying does and does not relieve stress. Frontiers in Psychology. Retrieved from https://www.frontiersin.org/articles/10.3389/fpsyg.2014.00871/full
9. Loftus, E. F. (1993). The reality of repressed memories. American Psychologist. Retrieved from https://psycnet.apa.org/record/1993-28899-001
10. Castellani, J. W., & Young, A. J. (2016). Human physiological responses to cold exposure: Acute responses and acclimatization to prolonged exposure. Autonomic Neuroscience. Retrieved from https://pubmed.ncbi.nlm.nih.gov/26924539/
11. Chung, K. F., & Pavord, I. D. (2008). Prevalence, pathogenesis, and causes of chronic cough. The Lancet. Retrieved from https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(08)60595-4/fulltext