Welcome to a whirlwind tour of ten truly 10 mind blowing reflexes that your body (or other creatures) performs on autopilot, often without you even realizing it. From underwater sleepers to spooky post‑mortem movements, each of these involuntary actions showcases nature’s clever shortcuts and, sometimes, its downright creepy side.
10 Mind Blowing Facts About Reflexes
10 Hippos Have a Reflex That Lets Them Sleep in Water Without Drowning
While humans often think they reign supreme in reflex wizardry, the animal kingdom boasts a parade of specialized automatic responses, and the hippopotamus is a star performer. These massive mammals spend most of their lives immersed, yet they cannot breathe underwater, so they’ve evolved a neat trick to stay afloat while snoozing.
When a hippo drifts beneath the surface, it can hold its breath for roughly five minutes before surfacing for air. This brief underwater nap is powered entirely by a reflex that forces the animal to rise, inhale, and then sink again, all without conscious thought.
The cycle repeats as the hippo’s brain automatically cues the next breath, allowing it to doze beneath the waves while remaining perfectly safe from drowning.
9 The Rectoanal Inhibitory Reflex Can Determine the Difference Between Gas and Stool
Our bodies host countless reflexes that act as quiet guardians, handling tasks too urgent for conscious oversight. One such unsung hero is the rectoanal inhibitory reflex, a subtle system that helps us tell the difference between a harmless puff of gas and an actual need to visit the bathroom.
When you’re asleep, this reflex springs into action: muscles in the rectum sense whether a simple release of air or solid waste is imminent. By distinguishing the two, it preserves continence and spares you from unnecessary nocturnal trips to the restroom.
Without this reflex, everyday life would be far messier, as the body would lack a rapid, automatic decision‑maker for such intimate matters.
8 The Arnold Reflex Causes You To Cough When the Ear Canal Is Stimulated
Coughs can spring from a myriad of sources—viruses, allergies, irritants—but there’s an obscure trigger that many never consider: the Arnold reflex. This reflex fires when the vagus nerve that passes through the auditory canal is irritated.
Imagine a stray cotton swab or a stubborn earwax buildup nudging that nerve; the brain interprets the signal as a need to clear the airway, prompting a cough. Even a brief, gentle poke inside the ear can set off a lingering cough that persists for weeks if left unchecked.
Simple ear irrigation or careful cleaning often resolves the issue, proving that a tiny stimulus in the ear can have a surprisingly loud respiratory response.
7 The Glabellar Reflex Allows You To Get Used to Being Tapped on the Forehead
Here’s a quirky reflex you can try on a willing friend: the glabellar reflex. Lightly tap the space between a person’s eyebrows, just above the nose, and watch them blink with each tap. After a few taps, the blinking stops—your brain has habituated to the repeated stimulus.
This seemingly trivial reaction serves a diagnostic purpose. In healthy adults, the reflex fades quickly; however, if someone continues to blink despite repeated taps, it may signal early neurological issues such as dementia or Alzheimer’s disease.
Thus, a simple forehead tap can become a window into brain health, offering clinicians a quick, non‑invasive screening tool.
6 Prune Fingers Are a Reflex Action
Ever emerged from a long soak only to discover your fingertips looking like tiny raisins? It’s not just excess water; it’s a reflex governed by the autonomic nervous system. When the skin’s blood vessels constrict after prolonged exposure to water, the surface skin wrinkles, creating a “prune” appearance.
Scientists believe this isn’t a random quirk. The tiny channels formed by the wrinkles improve grip on wet objects, allowing you to hold onto a slippery spoon or a wet rock more securely. Experiments have confirmed that people with wrinkled fingers perform better at gripping wet items than those with dry, smooth skin.
The reflex disappears if the nerves controlling the vessels are damaged, underscoring its reliance on neural signaling rather than mere water absorption.
5 The Bulbocavernous Reflex Can Test for Spinal Cord Injury
While the classic knee‑jerk test is a staple of medical check‑ups, some reflexes require a bit more… hands‑on investigation. The bulbocavernous reflex, for instance, helps doctors assess potential spinal cord damage.
To evaluate it, a clinician inserts a finger into the rectum to locate the bulbocavernous muscle. Then, using the opposite hand, they gently pinch the patient’s genitalia. If the muscle contracts, the reflex is intact; if not, it may indicate a spinal injury.
Although the procedure sounds uncomfortable, it provides crucial diagnostic information that other, less invasive tests might miss.
4 Goosebumps Are a Vestigial Reflex Action
When you shiver from cold or feel a sudden fright, those tiny bumps that rise on your skin are called goosebumps. Each bump results from an arrector pili muscle contracting beneath a hair follicle, a reflex inherited from our furry ancestors.
In animals, puffing up hairs creates an insulating layer against the cold or makes the creature appear larger to deter predators. In modern humans, the reflex persists even though we lack a dense fur coat, making the reaction more of a nostalgic reminder of our evolutionary past.
Thus, goosebumps remain a vestigial reflex—a harmless echo of a time when such a response could mean the difference between warmth and a predator’s attention.
3 REM Atonia Suppresses the Reflex Action That Causes Sneezes
On average, most people sneeze about four times a day. Yet you’ll never recall sneezing in the middle of a deep sleep. The reason? REM atonia—a temporary paralysis that occurs during rapid eye movement sleep, effectively silencing many reflexes, including the sneeze response.
This built‑in shutdown prevents the brain from sending motor signals that could cause you to act out your dreams, protecting you from potentially dangerous movements while unconscious.
Occasionally, the atonia can fail—think sleepwalkers or rare cases where a sneeze triggers an abrupt awakening. But under normal circumstances, REM atonia keeps you sneeze‑free while you’re dreaming.
2 Nerve Impulses Can Cause The Severed Head of a Dead Snake to Bite You
Survival experts warn that even after you decapitate a venomous snake, the detached head can still pose a danger. The nerves within the head remain alive for several hours, and when stimulated—by touching or moving the head—they can trigger a bite, injecting venom despite the lack of a body.
Instances of people being bitten by severed snake heads are not unheard of in regions where venomous snakes are common. The lingering reflex underscores the importance of handling even a headless snake with extreme caution.
1 The Lazarus Reflex Causes Braindead Patients to Raise Their Arms
Perhaps the most unsettling reflex of all belongs to the realm of horror movies: the Lazarus reflex. In rare cases, patients declared brain‑dead can still exhibit a brief, involuntary movement where they raise their arms and cross them over the chest, mimicking a vampire‑like pose.
This phenomenon, sometimes called the Lazarus sign, has been documented only a handful of times. In two recorded instances, patients survived more than 100 days after being pronounced brain‑dead, though the movement itself is purely a nerve‑driven spasm without any cortical involvement.
After the arms complete the eerie gesture, they simply flop back to the sides, leaving clinicians and onlookers equally fascinated and unnerved.