Anxiety: Causes, Symptoms & How To Retrain Your Brain® with Dr Elaine Ryan

There is nothing physically wrong with you, the symptoms of panic and anxiety are harmless if experienced appropriately. I’m a doctor of psychology and have experienced both anxiety and panic.  My purpose in telling you this, is to normalize your experience, as you may feel alone with what is happening. Anxiety, in one form or other, will be experienced by most of us at some stage. The problem is we do not speak about it – there is still stigma. I want to break down that stigma. In order to for me to ensure that you fully understand the symptoms that you are experiencing, I first need to explain your nervous system. It’s a bit long winded, but it is really important that you understand. 

Your Nervous System

The Autonomic Nervous System (ANS) is made up of The sympathetic nervous system SNS, and
The parasympathetic nervous system PNS.

You are normally not aware of the operating of the autonomic nervous system, ANS. It works away, in the background, away from your conscious thought. It works with no effort on your part, like a reflex, adapting and responding to your immediate environment.

It is useful to understand how it works, if you want to understand anxiety and the symptoms that you experience You may be more familiar with the sympathetic nervous system, being called, “fight or flight.” It activates when we perceive we are in some sort of danger.

The Autonomic Nervous System: Why Anxiety Feels So Physical

I’ve been a psychologist for over twenty years – and as someone who has personally experienced anxiety, I know how real and frightening the physical symptoms can be. Your heart races, your chest feels tight, your stomach churns, your head spins. It can feel as if your body is betraying you or that something is seriously wrong. But I promise, there is a biological reason for every sensation. It’s not “all in your head” – it’s your autonomic nervous system in action, triggering the well-known fight-or-flight response. In a way, your body is behaving exactly as it’s designed to when it thinks you’re in danger. Understanding this can be incredibly empowering: when you realise why these symptoms happen, they become a little less scary.

Fight-or-Flight: Your Sympathetic Nervous System on “Full Throttle”

When we perceive a threat (whether it’s a genuinely dangerous situation or just a high-pressure meeting at work), a tiny almond-shaped part of the brain called the amygdala sounds the alarm. Learn more about your amygdala and its role in anxiety.

Harvard Health notes your stress response starts in your brain once information comes via your eyes and alerts the amygdala, that something may be about to happen.

Think of the amygdala as your brain’s smoke detector – it’s always sniffing for danger. Once it detects a possible threat (even a false alarm), it instantly activates your sympathetic nervous system – the branch of your autonomic nervous system responsible for the fight-or-flight response. I often explain to my clients that this sympathetic system is like  putting your foot down on the car, all systems go. It sends a lightning-fast signal through your nerves to your adrenal glands (small glands atop your kidneys), telling them to pump out adrenaline (also known as epinephrine) and other stress hormones into your bloodstream and the brake, is like the parasympathetic system -, putting on the brakes to slow everything down again.

Adrenaline is like rocket fuel for your body – it produces a cascade of physical changes that prepare you to either fight for your life or run for the hills. Your heart pounds faster, sending blood rushing to your big muscles and vital organs. Your breathing quickens and your airways expand, pulling in more oxygen. Your blood pressure spikes to circulate that oxygen-rich blood efficiently. Extra oxygen even goes to your brain to make you alert.

Ever notice how you become hypersensitive to your surroundings when anxious? That’s because adrenaline literally sharpens your senses – eyesight and hearing become more acute (I joke that when I’m anxious I can hear a pin drop in the next room – my brain is on high alert, scanning for any sign of danger.) You might start sweating as your body anticipates intense activity and tries to cool you down. Sensory problems can be explained by this activation, as your pupils widen to let in more light, which can make your vision seem brighter or a bit unfocused (some people get blurry vision or “tunnel vision” during high anxiety) Essentially, your sympathetic nervous system has floored the accelerator – giving your body a burst of energy and reflexes to deal with a threat.

This response is amazingly helpful in true emergencies. If you nearly step in front of a bus, that surge of adrenaline and “supercharged” feeling might literally save your life by helping you jump back in time. The problem with anxiety is that the alarm often goes off when there’s no real danger – your body reacts to a stressor or even a worried thoughtas if you’re facing a predator. So you might be lying in bed or sitting in a meeting, and suddenly your heart is thumping and your hands are trembling as though you’re in great peril. It’s disconcerting, to say the least! I’ve had clients tell me, “I felt like I was having a heart attack while watching TV.” I reassure them (and myself when I feel it too) that this is just the sympathetic nervous system doing its job – albeit at the wrong time. Your internal “security system” has essentially triggered a false alarm, but the physical sensations are very real.

Why These Symptoms Happen (From Head to Toe)

Let’s break down some of the most common anxiety symptoms – and a few lesser-known ones – and explain how exactly the fight-or-flight response produces each one. As we go through them, you’ll see that everything you feel during anxiety has a purpose in the context of danger. Your body isn’t malfunctioning; in fact, it’s working beautifully to protect you (though it feels awful in a non-dangerous situation).

Heart Pounding / Palpitations and Chest Pain

One of the hallmark signs of anxiety is a racing, pounding heart. You might feel it hammering in your chest, fluttering, or skipping beats (palpitations). This can be terrifying – I’ve been there, lying in bed convinced I must be having a heart attack. In reality, this rapid heartbeat is your body’s way of delivering oxygen and energy where it’s needed. If you truly were in danger, a fast heart rate would help you run faster or fight harder by pumping blood to your muscles.

The trouble is, when you’re anxious at home, that pounding heart just feels scary. Sometimes the heart beating so hard can cause a sensation of chest tightness or pain. Anxiety-related chest pain is usually caused by a combination of muscle tension and breathing changes. When adrenaline hits, your chest muscles (and those between your ribs) may tense up as your body braces for action, or as Anxiety Canada aptly put it, to allow you to strike out. You might also start breathing very rapidly or hyperventilating without realising it. 

Hyperventilation (over-breathing) can cause chest discomfort in two ways: it can lead to muscle spasms in the chest wall and it causes your blood vessels to constrict, which can provoke chest pain. (It’s the same reason some people feel chest pain during a panic attack – it’s not a heart attack, but it feels awful.) The good news is that if your heart is healthy, anxiety chest pain is harmless and temporary. Once your breathing slows and your nervous system calms, that tight chest and thumping heart will pass. I find it helpful to remember that my heart is doing exactly what it’s supposed to in fight-or-flight mode – even if I don’t need all that blood flow right now. Sometimes I’ll even place my hand on my chest and think, “Okay, heart, thank you for trying to protect me. I’m not in danger, you can relax now.” This little acknowledgement can break the fear spiral and start to soothe my nerves.

Shortness of Breath & Dizziness

Along with a pounding heart, many people (myself included) experience shortness of breath or the feeling that they just can’t get enough air. You might take deep gulps, yawn a lot, or feel like you’re suffocating even though you’re actually breathing more than you need. This is usually due to over-breathing (hyperventilation) during high anxiety. Remember, your body is trying to supply extra oxygen for a fight or escape. Paradoxically, breathing too fast can make you feel breathless and light-headed. Here’s why: When you hyperventilate, you blow off too much carbon dioxide, which alters the balance of gases in your blood. Low CO2 causes blood vessels to narrow, according to my.clevelandclinic.org including those that supply the brain.

Less blood flow to your brain is what makes you feel dizzy, lightheaded, or faint – it’s like the woozy feeling after spinning around. I’ve had moments of acute panic where I suddenly go light-headed and my vision starts to dim at the edges; it’s scary, but it’s essentially because I was unconsciously over-breathing. The key thing to remember is that this dizziness and air hunger are not actually dangerous – you are not going to stop breathing or pass out (in fact, fainting from anxiety is uncommon because blood pressure is usually high, not low). Your body is actually getting plenty of oxygen; it’s just that the balance is off.

One trick I use is to slow down my breathing (for example, exhale slowly as if blowing out a candle, or breathe into cupped hands) to raise carbon dioxide back to normal – this often eases the dizzy, breathless feeling within a minute or two. Again, the symptom has a purpose: if you were about to sprint or fight, breathing fast is adaptive. But when you’re just sitting and worrying, it just makes you feel weird. Recognising that “Okay, I’m feeling dizzy because I’m anxious and my CO2 is low” can help you stay calm and ride it out until your body steadies.

Muscle Tension, Aches, and Trembling

Ever notice how tense your muscles get when you’re anxious? It’s as if your body is bracing for impact – which is exactly what it’s trying to do. Adrenaline prepares your muscles to spring into action. They tighten up to make you a smaller target and to ready themselves to either fight (think of a boxer tensing their muscles) or to run (a sprinter’s muscles primed to explode off the blocks).

This muscle tension can occur anywhere: you might clench your jaw (I personally get a stiff neck and jaw on stressful days), hunch your shoulders, or ball up your fists without noticing. Over time, this leads to soreness – I often hear people with anxiety complain of back pain, stiff neck, or headaches from chronically tight muscles. Sometimes the muscles shake or tremble, especially in the arms or legs. I’ve had clients describe their knees wobbling when they were anxious in a crowd, or their hands shaking during a panic attack. That trembling is a side effect of your muscles being flooded with adrenaline and energy. Think of a racing dog quivering at the starting line – so much energy is coursing through its muscles that it literally shakes. In anxiety, your body is ready to move now, but if you’re standing still, that energy has nowhere to go, resulting in visible shakes or internal jittery feelings. Again, it’s helpful to remember that this is normal: your body is behaving like a warrior gearing for battle. Once you start to calm down (or if you engage those muscles in actual movement, like taking a brisk walk), the trembling subsides as the excess adrenaline burns off. A useful tip: try progressive muscle relaxation or simply stretching/rolling your shoulders when you notice tension – this sends a signal to your brain that it’s okay to hit the brakes. Which brings us to…

“Rest-and-Digest”: The Parasympathetic System and Digestion

This is where you take your foot off the accelerator and hit the brakes. As I noted in the video at the start of this article, this occurs outside of your conscious awareness and is controlled automatically, but, fortunately for those of us with stress or anxiety, you can learn how to hit the brake yourself, and teach your body to calm down, but first I am going to explain what this ‘rest-and-digest’ system is.

 When your brain’s alarm is turned off, the parasympathetic system directs blood back to your internal organs, and digestion resumes its normal pace. But during anxiety, the brake is essentially off and the accelerator is floored, meaning digestion is not a priority. If you’ve ever had butterflies in your stomach before a big event, or an upset tummy when stressed, that’s fight-or-flight at work. The sympathetic response actually slows down your digestive process. Food might just sit there because, from your body’s perspective, why bother digesting lunch when you’re in danger? Better to save that energy for escaping. As a result, people with anxiety often experience nausea, indigestion, or stomach cramps. In my case, my appetite vanishes when I’m extremely anxious – my body effectively says “we’ll deal with food later.” On the flip side, some folks get increased acid production and heartburn (or reflux) because the stomach isn’t emptying normally. If the anxiety is severe enough (like a panic attack), you might even feel like you could vomit. It’s all part of the body’s way of clearing the decks for action.

Bowel and bladder

Along with stomach upset, bowel habits can change with anxiety. It’s not the most glamorous symptom, but it’s very common: stress can speed up bowel motility in some people, leading to urgent trips to the loo or even diarrhea. (There’s a reason for the old phrase “I was so scared I nearly s*** myself” – pardon the language – or having “the runs” from nerves.) On the other hand, ongoing anxiety can also contribute to constipation for some, since digestion is slowed; everyone’s gut response is a bit different.

And what about that classic nervous pee? Many of us find we have to urinate much more frequently when anxious. You might go to the toilet twice before an exam, or feel like a tiny bladder on a first date. This is an evolutionary quirk: in a real life-or-death scenario, emptying your bladder and bowels lightens your load so you can run faster. It’s truly a built-in survival mechanism – albeit an inconvenient one in modern life! The take-home point is that your churning stomach, knots in your gut, or sudden need to visit the bathroom are not random – they are direct results of your nervous system’s activation. As uncomfortable (and sometimes embarrassing) as these symptoms are, they make sense in light of the body’s strategy to protect you. When the danger (or rather, the false alarm) passes and your parasympathetic “brakes” kick back in, your digestion will normalize again – the butterflies calm down, nausea fades, and appetite returns.

Strange Sensations: Tingling, Numbness, Hot Flushes

Anxiety can produce some truly odd sensations. One common but often alarming symptom is a feeling of tingling or numbness, especially in the hands, feet, or face. The first time I experienced a full-blown panic attack, I remember my fingers went tingly and my face around my mouth felt almost numb – which, of course, made me panic even more. But here’s what’s happening: during fight-or-flight, blood is redirected away from your extremities (hands, feet, even skin) and sent to the big muscles and vital organs. This shunting of blood can cause a transient pins-and-needles feeling or numbness in the less critical areas.

Additionally, if you’re breathing rapidly, the changes in blood chemistry can contribute to that prickly sensation (people who over-breathe often get tingling in their fingers or lips). It’s actually the same mechanism as when your hand “falls asleep” from reduced circulation – anxiety is temporarily altering your circulation. Rest assured, it’s harmless and will reverse once you calm down and your blood flow normalises (in fact, tingling is often one of the first signs that you’re hyperventilating, and doing some slow breathing can help resolve it).

Anxiety can also play tricks with your body temperature. You might get sudden hot flushes (blushing bright red or feeling a rush of warmth to your face and neck) or, conversely, feel chilled to the bone with cold, clammy hands. The warmth and flushing come from adrenaline’s effect on blood vessels – in some cases, it causes them to dilate (open up) in your skin, leading to that wave of heat or redness (think of how some people’s faces turn red when they’re anxious or embarrassed – that’s adrenaline at work. On the other hand, blood being pulled to the core can leave your extremities cool, making you shiver or get goosebumps. I’ve had clients with social anxiety describe feeling their face burning with heat (blushing) during a stressful interaction, which only made them more self-conscious. It helps to know that this is a natural physiological response – your body is redirecting blood flow and pumping out heat as it revs up. Practically, if you’re dealing with this, using a cool cloth on your face or removing a sweater can provide relief for the hot flushes, and doing some jumping jacks can warm you up if anxiety gives you a chill. The main thing is: these sensations might feel bizarre, but they’re not dangerous. They are signs that your nervous system is in high gear.

Sight and hearing

Anxiety doesn’t only make you feel things more intensely in your body – it can also make the outside world seem louder, brighter, and harsher. This is another byproduct of adrenaline’s job of heightening your senses for survival. Vision changes are common: you might become sensitive to light, notice your surroundings look overly sharp or “too real,” or conversely experience a bit of blurriness. As mentioned, your pupils dilate during fight-or-flight to improve your vision in the dark or to spot movement easily. In a modern setting, that can mean indoor lights suddenly feel glaring or you see floaters or shadows that weren’t there before. Some people even get tunnel vision (where peripheral vision narrows) during panic – it’s the body’s way of focusing on the threat straight ahead. I’ve had times when anxiety made everything seem like it was in ultra-high definition, almost overwhelming my sight.

Similarly, hearing becomes more acute – your ears strain to pick up every sound of “potential danger.” This can make you jump when the phone rings or feel on edge about noises that normally wouldn’t bother you. On the flip side, some anxious folks report feeling distant or unreal, as if sounds are muted – this can be due to the mind dissociating a bit under stress, a way to tune out overwhelming input. But typically, it’s hyper-sensitivity. You’re essentially in hunter mode, like a deer perked up at every twig snap. While this sensory overload is uncomfortable (crowded places or bright stores might overstimulate you during high anxiety), remind yourself: my body is trying to protect me by boosting my senses. Once you relax, your pupils will constrict and your hearing will settle back to normal. Some find it helpful to wear sunglasses or noise-cancelling headphones in the throes of anxiety – a little trick to reduce input and signal to your frazzled brain that it’s okay to dial things down.

Insomnia and Restlessness 

One symptom that often gets overlooked in the moment (but we sure notice it at night) is difficulty sleeping when our anxiety has been high. After an anxious day, you might lie in bed utterly exhausted yet completely unable to fall asleep – your body and mind refuse to shut off. This is the classic fight-or-flight aftermath: your system is still flooded with adrenaline and cortisol (a longer-acting stress hormone), keeping you on alert. Stress hormones elevate your heart rate and body temperature, and stimulate your brain, making it hard to drift into sleep. In fact, the SleepFoundation notes studies have shown that stress and anxiety often lead to insomnia and other sleep problems. It becomes a vicious cycle because lack of sleep then makes you more anxious the next day, and so on.

I’ve had many nights where I’m tossing and turning because my body feels wired – my muscles are tense, I’m rehashing worries, and every time I start to drift, I get that jolt awake (sometimes called a “hypnic jerk,” which can be more frequent when you’re overstressed). This is essentially your nervous system having trouble shifting from the sympathetic (alert) state into the parasympathetic (relaxed) state. When we finally do fall asleep under high anxiety, the sleep might be light and filled with weird dreams, because our brain is still a bit on guard. If this happens to you, know that it’s very common. I often advise clients (and do myself) to practice a wind-down routine: dim lights, deep breathing exercises, maybe a calming herbal tea – basically, anything that tells your body “the danger has passed, you can power down now.” Over time, as you teach your body that it’s safe at night, your sleep can improve. And if you have an occasional rough night, remind yourself that even resting with eyes closed is helpful and that your body will eventually rebalance (I sometimes literally say to myself in the dark, “It’s okay, body, there’s no emergency now.” It sounds corny, but speaking to your anxious brain in a gentle, reassuring way can activate that calming parasympathetic response).

Feeling Empowered: Your Body’s Intention is Protection

That was a lot of information, but I hope walking through it this way helps you see a clear pattern: anxiety symptoms are the direct result of your body’s hardwired survival system. Every racing heartbeat, every bead of sweat, every jittery or queasy feeling – it’s all rooted in the fight-or-flight response that’s been with us since humans lived in caves. The range of symptoms is so wide because the autonomic nervous system touches nearly every part of the body (from your eyes to your gut to your skin). On the bright side, this means that these symptoms, as varied and upsetting as they are, are predictable and explainable by science. In my experience, both personally and professionally, understanding this brings a huge sense of relief. I vividly remember the first time I learned about the sympathetic nervous system in grad school – a lightbulb went off. So I’m not crazy, and I’m not dying – it’s just adrenaline and my anxious brain! This realization took away some of anxiety’s intimidating power over me.

Knowledge is power. When you notice your anxiety flaring up and your body revving into overdrive, try to remember: This is my autonomic nervous system trying to help me. It may be a false alarm, but my body doesn’t know that. Instead of feeling victim to your symptoms, you can almost take a curious observer stance: “Ah, my heart is racing and I have that lump in my throat – my fight-or-flight must have kicked in. Thanks, amygdala, but there’s no real danger right now.” It might sound funny to talk to your amygdala, but by responding to your symptoms with understanding (rather than panic), you’re engaging your thinking brain and telling the fear center that it can stand down. This compassionate self-talk can actually reduce the intensity of the symptoms. Remember, we also have that wonderful parasympathetic “brake” system. We can encourage it to activate through slow breathing, relaxation techniques, or even simple reassurances of safety. I often guide people through breathing exercises to stimulate the vagus nerve (a key nerve in the parasympathetic system) which helps calm the heart rate and relax the body. It’s pretty amazing – just as your body has a built-in way to rev you up, it also has built-in ways to slow you down. It might take some practice to fully tap into those, especially if your “alarm” has been oversensitive for a while, but it is possible.

Above all, I want you to take away that you are not alone in feeling these bizarre anxiety symptoms, and there’s nothing “weak” or “broken” about you for having them. I’ve worked with countless clients in Ireland and around the world who describe the exact sensations you do. And as someone who still wrestles with anxiety on occasion, I truly feel what you’re going through. These symptoms can be tough, but they are temporary and they will pass as your nervous system settles. By learning about the autonomic nervous system’s role, you’re equipping yourself with insight that can help you cope. Next time your heart is thudding or your vision goes funny from panic, you might remember this explanation and think, “Okay, this is uncomfortable but it’s my body’s natural response – I can ride this out.” In that moment, you move from fear to understanding, and from understanding to a bit more control. After all, what is anxiety itself but the feeling of not being in control? Explaining the science is one way to hand some control back to you. And from my 20+ years of experience, when you feel understood – even by yourself – and understand what’s happening in your body, the anxiety loses some of its grip. You’ve got this, and your body is on your side (even if it doesn’t feel like it at times).

In summary, the autonomic nervous system (through its sympathetic branch) orchestrates the wide range of anxiety symptoms we experience – from chest pain and dizziness to stomach upset and sleepless nights. It does so in an attempt to protect us, preparing our minds and bodies to face threats that often aren’t truly there. By recognising this and engaging the calming parasympathetic response, we can find ways to navigate anxiety with greater ease and self-compassion. Your body is not your enemy; it’s a guardian that sometimes sounds a false alarm. And with understanding, practice, and support, you can teach that guardian to be a little less jumpy, allowing you to reclaim calm and carry on with confidence.

Now that you understand what is behind all the symptoms you experience, I want to focus on, when and how you get anxious, as this information helps inform your treatment options.