Interoception: The Missing Piece Behind Anxiety That Makes No Sense

The Anxiety That Has No Name

Most of us grow up believing there are only five senses—sight, hearing, touch, taste, and smell. Yet science has uncovered a sixth, hidden in plain sight: a secret sense that constantly scans the inside of your body. Like a watchtower that never sleeps, it surveys the inner landscape, registering the pangs of hunger, the press of the bladder, the restless flutter of breath, the surge of your heart—all the signs of life unfolding beneath the surface. Sadly, a surprising number of people overlook these signals, or ignore them altogether, letting them blur into a vague sense of restlessness or unease. We are simply too busy dealing with the outside world or listening to our inner radio station transmitting a never-ending story—jacked with self-criticism, what-ifs, planning and organizing, as well as thoughts about the past and a future that may never come—to notice anything deeper.

Still, it’s there, the world beneath, waiting to be explored.

Science calls this hidden sense interoception—the body’s secret radar, forever scanning within. And herein lies a magnificent treasure—so powerful that once you learn to sharpen this sense and truly listen with clarity, chances are the grip of anxiety that has held you back for so long will begin to fade, or even loosen completely, giving rise to a sense of ease and control.

Julia turned over for the ninth, perhaps the tenth time, as though something inside her refused to rest, before letting her eyes drift toward the nightstand. She couldn’t fight it any longer—she had to know.

Across the phone’s screen, the digits glowed silently, like faint stars refusing to die out. 2:45 a.m. Stunned, she realized that more than 90 minutes had passed since she first woke in the darkness, seized by a wave of anxiety she could neither name nor trace. It felt almost like a familiar hangover dread, the kind that used to greet her after a night out with her friends, drinking. But that wasn’t the case tonight. She hadn’t touched alcohol in ages. Truth be told, she hardly drank at all anymore.

Still, the anxiety clung to her, tight and suffocating, like a wetsuit that refused to peel away. Confused, and in pursuit, she searched inward—through memories, through fragments of tomorrow—but nothing fit, nothing explained why she was suddenly wrapped in anxiety and sleeplessness. She wasn’t afraid of the coming day, not really, even if it involved boarding a plane and a quick trip with her colleagues. Flying had never frightened her; she almost welcomed the rhythm of travel. So it couldn’t be that. Nor did she find anything to worry about during the past week, not even the past month. Surprisingly, almost everything had flowed along just fine. It made no sense.

Even so, something wasn’t right. She must have missed a sign; anxiety couldn’t simply appear like this, out of the blue. In the middle of the night. She knew all too well what anxiety really was: a biological fire alarm deeply embedded in her mind, an ancient signal of imminent catastrophe, the kind of mechanism that had kept humans alive for millennia—hundreds of thousands of years, even. But tonight, there was no danger. No looming threat. Not even the echo of a frightening thought. Nothing. Only emptiness, however far she reached within herself for an explanation…

Worn down by the effort of trying to understand herself, her mind, and her emotions, she pushed back the covers, yanked the charger from her phone, and left the bedroom behind. She couldn’t stand tossing and turning anymore. It didn’t matter what time it was.

Since adolescence it had been like this. Not constant, but often enough. A few times each month — sometimes more, sometimes less. Anxiety that arrived uninvited, without reason, in the mornings, midday, evening, or even in the middle of the night. Just like that, as if it materialized inside her out of nowhere, lingering for hours, even days.

Devastated and torn, she had sought help more than once, tried medication and spoken with several psychologists. Yet, her inner guest always managed to slip away when she reached for treatment, only to return later, unannounced, once the sessions ended or the pills had worn thin. But that wasn’t the only problem. Seeking care weighed on her in other ways too. Doctors and therapists wanted to know the truth, and were always asking the same question, over and over: ‘Why are you anxious?’ ‘What are you afraid of?’ ‘What’s going on here?’ Questions she could seldom, if ever, answer. And that left her ashamed, wondering if she was broken at the core, missing an essential piece of herself. Surely a grown woman with a bachelor from MIT and a doctorate in aeronautical engineering from Caltech should be able to explain her own fear. But however she turned the puzzle pieces, no explanation ever fit. Which only deepened her sense of failure.

Whenever she found herself sinking into a soft armchair from yet another psychologist, a familiar feeling returned—of being foolish, childish, diminished. As if something inside her had been broken long ago, leaving her unable to grasp herself, her emotions, her own body—a world she could observe but never make sense of…

To explain her own fear felt like the bare minimum, something a child could do. Without that, how could anyone ever help her?

Her teenage years at Winchester College had been a quiet battle—to manage what she didn’t understand within herself, while also keeping any trace of it invisible to others. During her years in Hampshire, she had been too afraid to ask anyone for help. There was simply no one to turn to, no one who could truly understand her. In the end, she had no other option but to bite down hard and endure: through the nights, at school, on weekends and during holidays—always.

Once, when she couldn’t bear her inner storm any longer, she had cut herself on her wrist with a razor blade. Afterwards, the bed was drenched in blood, forcing her to wash everything between classes before the cleaning staff would discover what she had done to herself. And more than once, she had reached for alcohol, hoping to blunt the ghost inside her—the restless presence she couldn’t name or interpret. But fleeing never seemed to work, not for long. Quite the opposite, it made things worse. The moment she had cut herself, her mind was consumed by what might happen if someone found out—a thought that brought her more anxiety than anything else.

Unable to fall back asleep, she watched the hours slip away until the sky finally began to stir. Dark shadows dissolved into a faint blush of red—warm, alive, insistent, revealing the dawn of a beautiful day.

As she had done so many times before, she tried to mask the shadows beneath her eyes with makeup and walked with steady, resolute steps, wearing strength and agility like a costume. But that wasn’t all. Twice before boarding the plane, she stopped to refill her cup, as if freshly brewed coffee could patch the holes of a sleepless night.

Yet, nothing managed to veil the weight she was carrying. Her colleague saw straight through her—through the exhaustion, her facade and, of course, asked the obvious question. The simplest words, yet the hardest to answer: “How are you, really?”

Her thoughts spun. Was she going to hide it, deflect, lie? Or should she just speak the truth: “I’m anxious as hell. I’ve always been. But I have no fucking idea why.”

How Emotions Are Made: Top-down or Bottom-up

Strange as Julia’s story may seem, it is hardly rare. As a clinical psychologist, I can attest to that. The truth is that most people, at least to some extent, are struck by feelings they cannot clearly place or explain, sometimes several times a week. These mysterious phantoms simply rise up uninvited, offering no explanation, no context, leaving us with no clue why they appeared in the first place. Fortunately, most feelings drift past us like fading shadows, or burn out after a while without provoking an investigation or a second thought. In some cases, however, they linger, hours on end, strong as an ox, disrupting daily life through sleepless nights, confusion, avoidance, even self-destructive behaviors, just as in Julia’s case. Yet it doesn’t have to be this way—not if the right help is there to guide us.

Let me explain.

Our emotions—the ones that instantly come to mind, such as anxiety, fear, anger, joy, disgust, or sorrow—seem to arise like notes from a piano or colors on a painter’s palette. Feelings are just something that strike us, almost as if we were seated at a piano, playing along in a symphony. Whenever we press the C key, it yields the same note. The relationship seems to be fixed—at least as long as the instrument is in tune. We don’t need to give a single thought to the sound hidden within the keys; we already know exactly what sound will emerge the moment we touch the piano. In the same way, we know that a piano will never make a sound on its own, unless someone touches the keys. In other words, it doesn’t play without a pianist.

Intuitively, the same goes for our feelings. At least, that is how most people perceive the process and describe an emotional response. For example, heights, spiders, snakes, giving a presentation in front of your colleagues, or even darkness, may unleash fear and anxiety in many— just as a touch upon the keys awakens the voice of the piano. In the same way, sex or a delicious meal unleashes pleasure in most, almost as if there is some hidden one-to-one connection linking the two: stimulus – emotional response.

Sadly, however innate, and persuasive this idea may be, it is deeply misleading. Emotions don’t obey fixed keys or predictable notes, nor do they follow the same relationship that exists between a key and the corresponding note. In fact, most emotions are shaped and influenced by countless factors. To some extent, our emotions are made — or more precisely, assembled — like grand buildings, constructed from millions of tiny pieces, not merely triggered. And even if it doesn’t seem that way, this is where the real problem begins, within the process of constructing our emotions—where sensations are interpreted and shaped into feelings. For example, a disrupted process, or insufficient interoception, may give rise to profound suffering, especially anxiety, without leaving a single trace, just as in Julia’s case.

In plain terms, emotions emerge in two very different ways: top-down or bottom-up. Top-down emotions are born out of mental processes, such as thoughts, inner images or other forms of mental representations. For instance: picture yourself leaving the office late at night, when suddenly a sharp thought strikes your mind: Did I lock the door? Did I set the alarm? Sometimes this, or just a single image of an open window or a door, is enough to spark unease, even anxiety.

Anxiety emerging through top-down activity almost always occurs in conditions such as social anxiety, stage fright, phobias, or generalized anxiety disorder. For instance, people suffering from shyness or social anxiety often replay conversations they just had as mental representations in their minds, triggering catastrophic thoughts and ultimately anxiety. It is as if their own mind were conducting an interrogation, throwing out statements such as: “Should I have said something? Why didn’t I think of anything clever to say? Did I make a fool of myself?” Moreover, in stage fright, it’s not uncommon to picture the whole auditorium, the stage, the audience, the microphone, and the spotlights overhead in the mind. Images that are almost always enough to evoke anxiety.

In each of these examples, the anxiety is perceived as coherent and explainable. It makes sense. The mind knows where the threat lies. The threat may be exaggerated, even irrational, but we are not left in the dark.

Emotions arising from bottom-up processes, however, can throw everything off balance, as they lack a clear mental anchor. We are just standing there, or in Julia’s case, lying in bed, experiencing an emotion, without knowing why. It doesn’t matter how far we reach into the caverns of our own being; our bottom-up emotions can rarely be linked or connected to a thought, place, object or a mental image—at least not one we are conscious of. Instead, bottom-up emotions are assembled, or made, partly by a small region deep inside the brain called the insula, about the size of a thumb, which interprets bodily processes and sensations and relays these signals to other parts of the brain, where they’re given meaning, almost like an old-fashioned switchboard routing calls between body and mind. And here comes the kicker! Since the brain is primarily wired for survival, the insula is very eager to amplify and prioritize much of the incoming traffic from the body, making even faint signals stand out as if they carried urgent meaning, like a nervous air-traffic controller who mistakes every passing cloud for an incoming storm.

When the Brain Misreads the Body

Simply put, the insula operates according to a kind of default mode—better safe than sorry—which often results in vague, weak, or ambiguous signals arising within our own body, being interpreted as if something is wrong, which in turn gives rise to anxiety. A barely noticeable rise in heart rate, or slightly faster breathing, can, for example, be amplified and rerouted by the insula to the amygdala, which in many cases is enough to trigger anxiety—especially if the individual does not consciously notice the change in the body. Imagin the insula as the neighbor who always sits by the window, convinced that every shadow is a burglar. And, at the slightest movement on the street, he calls the police, “just to be safe.”

I know, this may sound odd, perhaps even counterintuitive, but the truth is that the brain is astonishingly quick to interpret the smallest variations in heartbeat, breath, and countless other processes as threats. And so it responds, not with calm, but with anxiety, or fear, without leaving us the slightest clue, which sadly is part of everyday life for many people.

A Night in a New Hotel — And Why You Couldn’t Sleep

To bring this process to life, picture yourself checking into a hotel in a foreign city, alone, with a task ahead of you—perhaps a work assignment, a job interview, or meeting a friend the following day. However, when you turn off the light and crawl into the sheets, listening to the city breathing outside, something begins to happen deep inside your brain and body—something you’re not aware of. As you fall asleep, a kind of safety protocol is activated, one that many researchers refer to as the First-Night Effect (FNE). This protocol tends to activate in most of us as we drift into sleep in an unfamiliar place, especially if we’re traveling alone.

To safeguard us from potential danger, our mind is forced to shift into a state of heightened vigilance. As a result, sleep becomes asymmetrical, with one hemisphere remaining more awake than the other, at least for the first couple of nights, until the FNE protocol has approved the hotel room and deemed it as safe. Moreover, falling asleep takes longer, rest is lighter, and awakenings occur more frequently. Muscle tension and stress hormones also tend to stay elevated as the sympathetic nervous system hums at higher speed. But that’s not all, your heart rate and breathing are likely to turn more erratic. All of this so that you can react quickly should anything threaten you in this unfamiliar environment.

But here’s the catch: many of these bodily adjustments also give rise to feelings. Put simply, the insula, together with other regions, interprets what’s happening in the body, the raised guard, and assembles an emotional state that mirrors this particular surge in activity. And just like that—voilà!—a bottom-up emotion is born. Unfortunately, at times, this state is interpreted as nothing other than anxiety. And to some extent, it makes sense—what emotion could possibly match a sudden surge in the sympathetic nervous system, in the middle of the night, better than anxiety itself?

Unfortunately, the less we understand or pay attention to what’s happening inside our bodies, the more likely we are to interpret it as anxiety—or at least as uneasiness. Hence, activity arising within the body can easily be classified as something abnormal and potentially threatening—especially when we don’t notice it happening. On the other hand: a cultivated interoception, the ability to notice what’s going on beneath the surface, reduces ambiguity and uncertainty, and with that, the likelihood that our bodily activity will give rise to anxiety or uneasiness. Consequently, your first night in an unfamiliar hotel—or for that matter, a haunted house—doesn’t have to end in anxiety or even discomfort. Your emotional experiences depend on how much you turn inward, on how well you can listen to your body’s quiet language. Frankly speaking, emotions are not prewritten; they are composed in real time.

Another example of bottom-up assembled emotions can be found in PMS or PMDD. Imagine the blur of a weekday morning—the alarm, the ceiling, the weight of another day beginning. Nothing in your life has changed: the same breakfast, the same route to work and the same people greeting you at the office. But inside your body, hormone levels have shifted dramatically in recent days. Estrogen has fallen, progesterone has risen and then begun to fall again, shifts that ripple through the brain’s chemistry, altering the balance of neurotransmitters such as serotonin and GABA. Still, however potent the shift may be, you never received the memo that your body has switched gears. In fact, all of this has unfolded in silence, beyond the reach of your awareness, busy tending to life: working, putting the kids to bed, and choosing pension funds.

Instead, you notice the chemical change when they reach your feelings: suddenly, the everyday noise at the office feels unbearable; a neutral text from a friend lands like rejection; and somehow, you’ve suddenly become terrible at your job. Meanwhile, the body is on high alert: your pulse quickens, sleep turns restless, and muscle tension builds.

Desperately, your insula—together with several other brain regions—makes its best guess at what’s going on. Should this state be interpreted as stress, anxiety, or even depression? Which one is it? Sadly, more often than not, our minds are eager to interpret the changes related to PMS and PMDD as irritability or outright anxiety, even though these shifts have nothing to do with any real threat or danger.

Just as with the First-Night Effect, the feeling isn’t primarily caused by something external but by an internal shift. The difference is that PMS is driven by an internal clock, while the First-Night Effect is triggered by environmental novelty—both, however, involve hormonal shifts in the brain and body that occur beyond our control. And since you can’t sense estrogen dropping, GABA faltering, or for that matter cortisol levels rising, the emotional experience becomes even more puzzling. What remains for the brain to do is to invent a story: something’s wrong, I must be in danger. And so, anxiety becomes the appropriate emotional state.

The same may happen with something as small as a change in breathing frequency. For example, some people are hypersensitive to fluctuations in carbon dioxide. A sigh, a yawn, or slightly faster breathing may expel enough CO₂ to disrupt the internal balance. As CO₂ levels drop, blood pH shifts. And so, the chemoreceptors in the brainstem register the change, and for some, even the tiniest shift is read as a threat to the body’s stability. The result: a sudden surge of anxiety or fear—even without feeling short of breath.

The insula is always at work, translating the body’s internal signals into emotions. It listens to the pulse, the gut, the breath, and turns those shifting patterns into feelings. Most of the time, this process runs quietly in the background. And here is where our troubles begin—especially when we remain unaware of what’s happening inside us, which is, more often than not, the case.

Of course, none of us are truly doomed, we don’t need to get caught up in this drama—we can actually do something about it! With that being said, we rarely have any real say over the processes that drive changes inside our bodies. Women, for example, can’t turn off their hormonal cycles or pause menstruation at will, even though certain medications—like birth control—can influence the process to some extent. Nor can we persuade our minds that it’s perfectly safe to sleep in a new place and simply switch off the First-Night Effect. Likewise, we don’t have any authority over our senses—what stimuli come in, how the amygdala, the brain’s built-in sentry, reacts to them, or how the thalamus and the sympathetic nervous system respond in return. These systems and most of the processes lie outside our control, and certainly outside conscious awareness.

Interoception: The Quiet Skill That Changes Everything

What we can influence, however— and here’s the turning point—is our own insight, which is a powerful card to play. More precisely, the way we notice and interpret what is happening inside our bodies. At first glance, this may sound like a faint consolation, a fragile remedy for deep and persisting anxiety. But it is not. Gaining insight into and understanding bodily processes has, in fact, been shown in several peer-reviewed reports to make a decisive difference when it comes to anxiety and distress, even in clinical settings such as Julia’s. For example, interoceptive training has been found to reduce panic-related fear of internal sensations, alleviate anxiety and depressive symptoms as well as improve emotional regulation.

Let me explain.

By learning to understand our own bodies—what’s really going on beneath the surface—and by putting words to our sensations as we notice them, and practice interpreting them, it’s possible to quiet the brain’s emotional default mode and open the door to a more nuanced understanding. On a neurological level, refined interoception allows the raw, automatic responses from the amygdala, the brainstem’s chemoreceptors and so on, to be complemented by prefrontal and insular networks. As a consequence, bodily signals are no longer interpreted as an undifferentiated threat but are instead processed and understood in a more nuanced way. For example, signals may be recognized as hunger, fatigue, or nervousness rather than pure danger.

Fewer False Alarms. More Emotional Clarity.

In addition, refined interoception increases activity in the ventromedial prefrontal cortex, an area at the very front of the brain tasked with regulating and dampening the amygdala’s threat response, which translates into fewer false alarms from the body, less anxiety, and a more balanced emotional landscape.

As a bonus, a more cultivated interoception also builds stress resilience, aids recovery, and makes the nervous system less reactive—an advantage spanning across several patient groups, not just in anxiety, but also exhaustion, sleep difficulties, and chronic fatigue. In fact, regular training of interoception has even been linked to lower levels of cortisol—the body’s primary stress hormone—and faster recovery after a stress response.

Still, that’s not all. If we manage to stop, or at least reframe, a bottom-up signal, transforming it from a threat into what it actually is, for example, a stronger heartbeat or a shallow breath, the likelihood of breaking the downward spiral that so often rests on misinterpretations of normal bodily changes rises sharply. As it happens, dramatic interpretations of physical reactions almost always lead to something more than just anxiety or fear; they provide the body with new instructions, which in turn generate further physical changes, such as an even harder heartbeat or an even faster breath—sensations once again interpreted by the mind as danger. And so, the cycle continues. In other words, dramatic interpretations have a strong tendency to reinforce themselves, bouncing back and forth between body and brain like an echo rolling through a canyon. Hence, breaking that cycle by cultivating interoception is nothing less than a quiet revolution within the self.