I Can’t Sleep - Whiskers | Gentle Bedtime Reading for Sleep

Episode Date: September 22, 2025

Relax with calm, bedtime reading to help you drift into a peaceful sleep and ease insomnia. In this episode we explore whiskers—special tactile hairs (vibrissae) many mammals have—and how they work to let animals feel their surroundings, hunt, and avoid danger. You’ll learn about the anatomy of whiskers, how they move, and why they’re different from regular fur. Benjamin’s voice will guide you softly as you discover facts without any whispering or hypnosis. Great for restless nights, curious minds, and finding calm. Press play and let yourself drift off. Happy sleeping! Read with permission from Whiskers, Wikipedia (https://en.wikipedia.org/wiki/Whiskers), licensed under CC BY‑SA 4.0. Learn more about your ad choices. Visit megaphone.fm/adchoices

You're listening to a Glassbox Media podcast. What if I told you that most of the modern day self-help advice you've been hearing could actually make you worse? The key to a better life isn't about feel-good gimmicks that sound catchy. The Mentally Stronger Podcast gives you access to a licensed therapist who shares science-backed tools that will actually change your life. Hi, I'm Amy Morin, psychotherapist, mental strength trainer, and international best-selling author. In each episode, we cover research-back strategies, like how to stop relying on willpower and start creating habits for lasting change. And the five mental strength-building exercises you can do from your couch. I also speak to world-class experts like Dr. Nicole Kane, who shares how to permanently heal anxiety by addressing the root cause.

With over 200 episodes in our catalog, this podcast is for you if you're ready to crush self-doubt, conquer challenges, become stronger than ever with therapist-approved strategies that can change your life. Listen to Mentally Stronger with Therapist Amy Morin, wherever you get your podcasts. Welcome to the I Can't Sleep podcast, where I help you drift off one fact at a time. I'm your host, Benjamin Boster, and today's episode is about Whiskers. Thanks to Nick Saunders for sponsoring today's episode. Whiskers, also known as Vibrissi, are a type of stiff, functional hair used by most Therian mammals to sense their environment. These hairs are finely specialized for this purpose, whereas other types of hair are coarser as tactile sensors.

Although whiskers are specifically those found around the face, Vibrissi are known to grow in clusters at various places. around the body. Most mammals have them, including all non-human primates, marsupials, and especially nocturnal mammals. Monotremes, however, lack them. Whiskers are sensitive tactile hairs that aid navigation, locomotion, exploration, hunting, social touch, and perform other functions. This article is primarily about the specialized sensing hairs of mammals, But some birds, fish, insects, crustaceans, and other orthopods are known to have similar structures, also used to sense the environment. Vibrissi, from Latin Vibraré, to vibrate, from the characteristic motion seen in a small rodent

that is otherwise sitting still. In medicine, the term also refers to the thick hairs found inside human nostrils. The last common ancestor of all extant mammals had Vibrissi. all other extant mammal species besides great apes retain the same ancestral layout of the whiskers along with the special facial muscles that move them fibrici are anatomically distinguished from other hair they are easily visually identified since they are longer stiffer significantly larger in diameter and stand above the surrounding fur by a considerable amount in addition they have well well-intervented follicles and an identifiable representation in the somatosensory cortex of the brain. The largest number and the longest are found among the small social arboreal and nocturnal mammals. Whiskers of aquatic mammals are the most sensitive.

During foraging and complex dark habitats, whiskers are rapidly moved in a cyclic way, tracing small circles, at their tips. This motion, called whisking, can occur at speeds of 25 hertz in mice, which is one of the fastest movements that mammals can make. Small animals use whisking to position their front paws during locomotion. Vibrisi typically grow in clusters. These groups vary somewhat in form and function, but they are relatively consistent among land mammals. Between land and marine mammals, there is less consistency, though commonalities are

certainly present. Many land mammals like rats and hamsters have four typical whisker groups on their heads called a cranial vibranial, which might vary among animals due to different lifestyles. These cranial groups include above the eyes, superorbital, on the cheeks, genal, where the mustache would be, moustacheal, under the snout, mandibular. The moustacheal whiskers can be roughly identified as macro-vibrisy, long whiskers for feeling the space around the head, and micro-vibrisy, small down-pointing whiskers for identifying objects. Not only are these two types hard to distinguish on an animal's face, there are similarly weak distinctions on how they are used, though the distinction is nonetheless referred to ubiquitously in scientific literature

and is considered useful in analysis. Many land mammals, including domestic cats, also have vibrancy on the underside of the leg, just above the paws, called carpal vibrancy. While these five major groups are often reported in studies of land mammals, several other groups have been reported more occasionally. For instance, nasal, angular, and submental whiskers. Marine mammals can have substantially different arrangements of their vibrancy. For instance, whales and dolphins have lost their snout whiskers

and gained vibrancy around their blowholes, whereas every single one of the body hairs of the Florida manatee may be a vibresa. Other marine mammals, like seals and sea lions, have head vibrancy just like those on land mammals, although these groups function quite differently. Vibrousal follicles have evolved other functions in dolphins, such as electroreception. The vibrousal hair is usually sicker and stiffer than other types of polysophil follicles, have evolved other functions in dolphins, such as electroreception. halagic hair. But like other hairs, the shaft consists of an inert material keratin and contains no nerves. However, Vibrisi are different from other hair structures because they grow from a special

hair follicle incorporating a capsule of blood called a blood sinus, which is heavily innervated by sensory nerves. Vibrisi are symmetrically arranged in groups on the face, and supply the trigeminal nerve the mustatial macro vibrasy are shared by a large group of land and marine mammals and it is this group that has received by far the most scientific study the arrangement of these whiskers is not random they form an ordered grid of arcs columns and rows with shorter whiskers at the front and longer whiskers at the rear in the mouse gerbil hamster rat guinea pig rabbit and cat each individual follicle is innervated by one hundred to two hundred primary aphorant nerve cells these cells serve an even larger number of mechanoreceptors of at least eight distinct types accordingly even small deflections of the vibrousal hair can evoke a sensory response in the animal Rats and mice typically have approximately 30 microvibrisy on each side of the face, with whisker lengths up to around 50 millimeters in laboratory rats,

30 millimeters in laboratory mice, and a slightly larger number of microvibrisy. Thus, an estimate for the total number of sensory nerve cells surveying the mustatial vibristle array on the face of a rat or mouse might be 25,000. Natural shapes of rats' mustatial pad vibrisi are well approximated by pieces of the euler spiral. When all these pieces for a single rat are assembled together, they span an interval extending from one coiled domain of the euler spiral to the other. Marine mammals may make even greater investment in the vibrousal sensory system than rats and mice.

seal whiskers, which are similarly arrayed across the mustatial region, are each served by around ten times as many nerve fibers as those in rats and mice, so that the total number of nerve cells innervating the mustatial vibrisy of a seal has been estimated to be in excess of 300,000. Manatees, remarkably, have around 600 vibrisy on or around their lips. Whiskers can be very long in some species. The length of a chinchilla's whiskers can be more than a third of its body length. Even in species with shorter whiskers, they can be very prominent appendages. Thus, whilst whiskers certainly could be described as proximal sensors, in contrast to, say, eyes, they offer a tactile sense with a sensing range that is functionally very significant.

The follicles of some groups of vibrisi and some species are motile. Generally, the superorbital, genal, and macrovibrisi are motile, whereas the microvibricy are not. This is reflected in anatomical reports that have identified musculature associated with the macrovibrisi that is absent for the microvebrisci. A small muscle sling is attached to each microvibrisa and can move it more or less independently of the others. While its larger muscles in the surrounding tissue move many or all of the macrovibrisi together. Amongst those species with motile macrovibrisi, some rats, mice, flying squirrels, gerbils, chinchillas, hamsters, shrews, porcupines, apocytes, apocytes. move them back and forth periodically in a movement known as whisking.

While other species, cats, dogs, raccoons, pandas do not appear to, the distribution of mechanoreceptor types in the whisker follicle differs between rats and cats, which may correspond to this difference in the way they are used. Whisking movements are amongst the fastest produced by mammals, and all whisking animals in which it has so far been measured. These whisking movements are rapidly controlled in response to behavioral and environmental conditions. The whisking movements occur in bouts of variable duration, and at rates between three and 25 whisks per second.

Movements of the whiskers are closely coordinated with those of the head and body. Generally, vibrici are considered to mediate a tactile sense, complementary to that of skin. This is presumed to be advantageous in particular to animals that cannot always rely on site to navigate fortified food. For example, nocturnal animals or animals which forage in muddy waters. Whiskers can also function as wind-detecting antennae, such as the superorbital ones in routes. sensory function aside movements of the vibrisi may also indicate something of the state of mind of the animal and the whiskers play a role in social behavior of rats the sensory function of vibrisi is an active research area experiments to establish the capabilities of whiskers use a variety of techniques including temporary deprivation either of the whisker's sense or of other senses animals can be deprived of their whiskers sense for a period of weeks by whisker trimming they soon grow back or for the duration of an experimental trial by restraining the whiskers with a flexible cover like a mask

the latter technique is used in particular in studies of marine mammals such experiments have shown that whiskers are required for or contribute to object localization orientation of the snout Detection of movement. Texture discrimination. Shape discrimination. Exploration. Sigma taxis. Locomotion. Maintenance of equilibrium.

Maze learning. Swimming. Locating food pellets. Locating food animals. And fighting. Whisking, the periodic movement of the whiskers, is also presumed to serve a tactile sensing in some way. however exactly why an animal might be driven to beat the night with sticks as one researcher once put it is a matter of debate and the answer is probably multifaceted

scullerpedia offers since rapid movement of the vibrescy consumes energy and has required the evolution of specialized musculature it can be assumed that whisking must convey some sensory advantages to the animal likely benefits are that it provides more degrees of freedom for sensor positioning that it allows the animal to sample a large volume of space with a given density of whiskers and that it allows control over the velocity with which the whiskers contact surfaces animals that do not whisk but have motile whiskers presumably also gain some advantage from the investment in musculature anecdotally it is often stated that cats use their whiskers to gauge whether an opening is wide enough for their body to pass through this is sometimes supported by the statement that the whiskers of individual cats extend out to about the same width as the cat's body but at least two informal reports indicate that whiskers length is genetically determined and does not vary as the cat grows thinner or fatter in the laboratory rats are able to accurately discriminate the size of an opening so it seems likely that cats can use their whiskers for this purpose however reports of cats particularly kittens with their heads firmly stuck in some discarded receptacle are common in place, indicating that if a cat has this information available, it does not always make best use of it. Pinnipeds have well-developed tactile senses. Their mastaceal vibrisi have ten times the

innervation of terrestrial mammals, allowing them to effectively detect vibrations in the water. These vibrations are generated, for example, when a fish swims through water. detecting vibrations is useful when the animals are foraging and may add to or even replace vision, particularly in darkness. Barber seals have been observed following varying paths of other organisms that swam ahead several minutes before, similar to a dog following a scent trail, and even to discriminate the species in the size of the fish responsible for the trail.

Blind seals have even been observed successfully hunting on their own in Lake Sima, likely relying on their vibrancy to gain sensory information and catch prey. Unlike terrestrial mammals such as rodents, penipeds do not move their vibrescy over an object when examining it, but instead extend their movable whiskers and keep them in the same position. By holding their vibrisy steady, pinnipeds are able to maximize their detection ability. The vibresi of seals are undulated and wavy, while sea lion and walrus vibrisy are smooth.

Research is ongoing to determine the function of any of these shapes on detection ability. The vibrisse's angle relative to the flow, and not the fiber shape, however, seems to be the most important factor. Most cetaceans have whiskers at birth, but they are typically lost during maturation. The follicles in any vestigial hair

sometimes function as touch or electrical sense organs. A large part of the brain of whiskers' specialist mammals is involved in the processing of nerve impulses from fibricis. A fact that presumably corresponds to the important, position the sense occupies for the animal. Information from the vibrisi arrives in the brain via the trigeminal nerve and is delivered first into the trigeminal sensory complex of brainstem. From there, the most studied pathways are those leading up through parts of thalamus and into

beryl cortex. Though other major pathways through the superior caliculus and midbrain, a major visual structure in visual animals, and the cerebellum, to name but a couple, are increasingly coming under scrutiny. Neuroscientists and other researchers studying sensory systems favor the whisker system for a number of reasons, not least the simple fact that laboratory rats and mice are whisker

rather than visual specialists. The presence of mustatial vibrisi in distinct lineages, with remarkable conservation of operation suggests that they may be an old feature present in a common ancestor of all therian mammals. Indeed, some humans even still develop vestigial-vibrous muscles in the upper lip, consistent with the hypothesis that previous members of the human lineage had mastaceal vibrisi. Thus, it is possible that the development of the whiskers sensory system played an important role in mammalian development more generally. Researchers have begun to build artificial whiskers of a variety of types,

both to help them understand how biological whiskers work and as a tactile sense for robots. These efforts range from the abstract through feature-specific models to attempts to reproduce complete whiskered animals in robot form, ScratchBot and Shrewbot, both robots by Bristol Robotics Laboratory. A range of non-mammals possess structures which resemble or function similarly to mammalian whiskers. Some birds possess specialized hair-like feathers called rectal bristles are on the base of the beak, which are sometimes referred to as whiskers.

The whiskered ocklet has striking, stiff white feathers protruding from above and below the eyes of the otherwise slate gray bird, and a dark plume which swoops forward from the top of its head. Whiskered ocklets sent through a maze of tunnels with their feathers taped back, bumped their heads more than twice as often as they did when their feathers were free, indicating they used their feathers in a similar way to cats. Other birds that have obvious whiskers are kiwis, flycatchers, swallows, night jars, whip-pour-wills, a cacopoe, and the long whiskered alid. Some fish have slender, pendulous, tactile organs near the mouth.

These are often referred to as whiskers, although they are more correctly termed barbels. Fish that have barbels include the catfish, carp, goatfish, agfish, sturgeon, zebrafish, and some species of shark. The pymelodity are a family of catfish commonly known as the long-whiskered catfishes. Anurognosid terasaurus had arugose, wrinkled jaw texture, that has been interpreted as the attachment sites for vibrisi, though actual vibrisi have not been recorded. More recently, a specific type of feathers has been found around anuragnosid

mouths. A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although in some cultures five human senses were traditionally identified as such, namely sight, smell, touch, taste, and hearing, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli, such as the sound or smell for transduction, meaning transformation into a form that can be understood by the brain.

Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior, and thought. In organisms, a sensory organ consists of a group of interrelated sensory cells that respond to a specific type of physical stimulus. Via cranial and spinal nerves, nerves of the central and peripheral nervous systems that relay sensory information to and from the brain and body. The different types of sensory receptor cells and sensory organs transduct sensory information

from these organs towards the central nervous system, finally arriving at the sensory cortices in the brain, where sensory signals are processed and interpreted or perceived. Sensory systems or senses are often divided into external, extroception, and internal interception sensory systems. Human external senses are based on the sensory organs of the eyes, ears, skin, nose, and mouth. Internal sensation detect stimuli from internal organs. and tissues.

Internal senses possessed by humans include spatial orientation, proprioception, body position, both perceived by the vestibular system located inside the ears, and nauseception, pain. Further internal senses lead to signals such as hunger, thirst, suffocation, and nausea, or different involuntary behaviors such as vomiting. Some animals are able to detect electrical and magnetic fields, air moisture, or polarized light, while others sense and perceive through alternative systems, such as echolocation. Sensory modalities or submodalities are different ways sensory information is encoded or transduced.

Multimodality integrates different. senses into one unified perceptual experience. For example, information from one sense has the potential to influence how information from another is perceived. Sensation and perception are studied by a variety of related fields, most notably psychophysics, neurobiology, cognitive psychology, and cognitive science. Non-human animals experience sensation and perception with varying levels of similarity to and difference from humans and other animal species. For example, other mammals in general have a stronger sense of smell than humans. Some animal species lack one or more human sensory system analogs, and some have sensory systems that are not found in humans.

while others process and interpret the same sensory information in very different ways. For example, some animals are able to detect electrical fields and magnetic fields, air moisture, or polarized light. Others sense and perceive through alternative systems such as echolocation. Recent theory suggests that plants and artificial agents such as robots may be able to detect and interpret environmental information. in an analogous manner to animals. Sensory modality refers to the way that information is encoded, which is similar to the idea of transduction. The main sensory modalities can be described on the basis of how each is transduced.

Listing all the different sensory modalities, which can number as many as 17, involves separating the major senses into more specific categories or submodalities of the larger sense. An individual sensory modality represents the sensation of a specific type of stimulus. For example, the general sensation and perception of touch, which is known as somatosensation, can be separated into light pressure, deep pressure, vibration, itch, pain, temperature, or hair movement, while the general sensation and perception of taste can be separated into submodalities of sweet, salty, sour, bitter, spicy, and umami, all of which are based on different chemical binding to sensory neurons. Sensory receptors are the cells or structures that detect sensations.

Stimuli in the environment activates specialized receptor cells in the peripheral nervous system. During transduction, the physical stimulus is converted into action potential by receptors, and transmitted towards the central nervous system for processing. Different types of stimuli are sensed by different types of receptor cells. Receptor cells can be classified into types on the basis of three different criteria, cell type, position, and function. Receptors can be classified structurally on the basis of cell type in their position in relation to stimuli they sense.

Receptors can further be classified functionally on the basis of the transduction of stimuli, or how the mechanical stimulus, light, or chemical change the cell membrane potential. One way to classify receptors is based on their location relative to the stimuli. An exoreceptor is a receptor that is located near a stimulus of the external environment, such as the somatosensory receptors that are located in the skin. An inter receptor is one that interprets stimuli from internal organs and tissues, such as the receptors that sense the increase in blood pressure and the aorta or carotid sinus. The cells that interpret information about the environment can be either one,

a neuron that has a free nerve ending, with dendrites embedded in tissue that would receive a sensation. 2. A neuron that has an encapsulated ending in which the same, sensory nerve endings are encapsulated in connective tissue that enhances their sensitivity. For three, a specialized receptor cell which has distinct structural components that interpret a specific type of stimulus. The pain and temperature receptors in the dermis of the skin are examples of neurons that have free nerve endings. Also located in the dermis of the skin are lamillated corpuscles, neurons with encapsulated nerve endings that respond to pressure and touch.

The cells in the retina that respond to light stimuli are an example of a specialized receptor, a photoreceptor. A transmembrane protein receptor is a protein in the cell membrane that mediates a physiological change in a neuron. Most often through the opening of ion channels, or changes in the cell, signaling processes. Transmembrane receptors are activated by chemicals called ligands. For example, a molecule and a food can serve as a ligand for taste receptors. Other transmembrane proteins, which are not accurately called receptors, are sensitive to mechanical or thermal changes. Physical changes in these proteins increase ion flow across the membrane and can generate an action potential or a graded potential in the sensory neurons. A third classification of receptors is by how the receptor

transduces stimuli into membrane potential changes. Stimuli are of three general types. Some stimuli are ions and macromolecules that affects transmembrane receptor proteins when these chemicals diffuse across the cell membrane. Some stimuli are physical variations in the environment that affect receptor cell membrane potentials. Other stimuli include the electromagnetic radiation from visible light. For humans, the only electromagnetic energy that is perceived by our eyes is visible light. Some other organisms have receptors that humans lack, such as the heat sensors of snakes, the ultraviolet light sensors of bees, or magnetic receptors in migratory birds. Receptor cells can be further categorized on the basis of the type of stimuli they transduce.

The different types of functional receptor cell types are mechanoreceptors, photoreceptors, photoreceptors, chemoreceptors, thermoreceptors, electroreceptors in certain mammals and fish, and nosocirceptors. Physical stimuli such as pressure and vibration, as well as a sensation of sound and body position, balance, are interpreted through a mechanoreceptor. Photoreceptors convert light, visible electromagnetic radiation, into signals.

Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli, such as an object state or smell, while osmo receptors respond to a chemical solute concentrations of body fluids. Nassusception, pain, interprets the presence of tissue damage from sensory information, from mechano, chemo, and thermoreceptors. another physical stimulus that has its own type of receptor is temperature which is sense through a thermal receptor that is either sensitive to temperatures above heat or below cold normal body temperature