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Knowledge Base » Mental Health » The Physiological Responses Associated with Anxiety

The Physiological Responses Associated with Anxiety

Approximately 1 in 4 people in the UK will experience a mental health problem each year, and the number of people who self-harm or have suicidal thoughts is increasing. 

According to Mental Health UK, a little over 1 in 10 of us will be living with an anxiety disorder at any one time. Anxiety is a feeling of unease, a feeling of worry or fear that can range from being mild to severe. Anxiety is usually experienced as a combination of physical sensations, thoughts and feelings. Anxiety can feel like you are constantly worrying about things, have a sense of dread and you may have difficulty concentrating. Feeling anxious occasionally is different to having an anxiety disorder. Feeling occasionally anxious is a normal part of everyday life. Many people worry about things such as their health, money worries, or family problems. However, anxiety disorders involve more than just a temporary worry or fear. For people with an anxiety disorder, the anxiety does not go away when the problem resolves and it can get worse over time. 

Signs and symptoms of anxiety disorder may include:

  • Excessive, intense and persistent worry that is not proportionate to the actual threat or situation.
  • It may feel difficult to control.
  • It will often interfere with your daily activities, work and relationships, and affect your overall quality of life.
  • It may lead to avoidance of certain situations or activities.
  • It will usually be persistent and chronic, lasting for six months or more.
  • The feeling of worry may be present even when there is no immediate cause for concern.
  • Feelings of dread, panic or ‘impending doom’.
  • Uncontrollable overthinking.
  • Changes in appetite over a prolonged period of time.
  • Dissociation, which is feeling like you aren’t connected to your own body, watching things happen around you without really feeling it.
  • It may not have an obvious trigger, or the trigger may be disproportionate to the situation and the level of anxiety experienced.
  • You may experience intense physical symptoms such as muscle tension, headaches, nausea, sweating, trembling and difficulty concentrating.
  • It may affect your ability to sleep.
  • It will often require professional intervention, such as therapy or medication, to manage the symptoms effectively.

There are several types of anxiety disorders, including:

  • Generalised anxiety disorder (GAD) – this is chronic anxiety that can last for months or years. There may be no particular cause for the anxiety.
  • Panic disorder – people with this type of anxiety have frequent panic attacks that can come on unexpectedly.
  • Social anxiety disorder – this involves intense fear of social situations in which a person may be watched or judged.
  • Phobia-related disorders – phobias relate to fear and aversion to specific objects and situations.
Fight-or-Flight Response

Fight-or-Flight Response

The fight-or-flight response, which is also known as the acute stress response, is a physiological reaction that occurs in response to a perceived harmful event, attack or threat to survival. It is a natural survival mechanism that prepares us to either confront the danger or flee from it.

When the brain perceives a threat, it triggers the release of stress hormones such as adrenaline and cortisol. These hormones increase your heart rate, blood pressure and breathing rate, while also redirecting blood flow to muscles, increasing energy levels, and sharpening focus and reflexes. These changes prepare the body for immediate action to either confront the threat or escape from it.

The fight-or-flight response evolved as a way for organisms to react quickly to dangerous situations, enhancing their chances of survival in the face of threats. While it’s an adaptive response in short-term situations, prolonged activation of the fight-or-flight response can have negative effects on health, leading to chronic stress-related disorders if not managed properly.

Impact on the Nervous System

Anxiety triggers the body’s fight-or-flight response, leading to the activation of the sympathetic nervous system. This results in the release of stress hormones like adrenaline and cortisol, which prepare the body to respond to perceived threats. These hormones increase heart rate, blood pressure and respiration rate, as well as other physiological changes.  

Anxiety can lead to a state of hypervigilance, where people become excessively alert and sensitive to potential threats and have a tendency to perceive even minor events as threatening. 

Other ways the nervous system can be impacted include:

  • Amygdala activation – the amygdala, a region of the brain involved in processing emotions, particularly fear and anxiety, can become hyperactive in people experiencing anxiety. This heightened activity can contribute to fear responses and difficulty in regulating emotions.
  • Hippocampal changes – chronic anxiety has been associated with structural changes in the hippocampus, a brain region involved in memory and emotional regulation. Prolonged exposure to stress hormones like cortisol can lead to a decrease in the volume of the hippocampus, which may impair cognitive function and increase vulnerability to further anxiety.
  • Neurotransmitter imbalance – anxiety is linked to alterations in neurotransmitter levels in the brain. Imbalances in neurotransmitters such as serotonin, dopamine and gamma-aminobutyric acid (GABA) are commonly observed in people with anxiety disorders. These neurotransmitters play crucial roles in mood regulation, and their dysregulation can contribute to the development and maintenance of anxiety symptoms.
  • Chronic stress – persistent anxiety can lead to chronic stress, which can have serious effects on the nervous system. This can impair cognitive function, mood regulation and stress resilience over time.
  • Somatic symptoms – anxiety can manifest with a range of somatic symptoms, such as muscle tension, headaches, gastrointestinal disturbances and fatigue. These symptoms often result from the physiological manifestations of the body’s stress response and can further exacerbate feelings of anxiety and distress.

Cardiovascular Effects

In some cases, anxiety can have significant effects on the cardiovascular system, both in the short term and over prolonged periods. Some of the cardiovascular effects associated with anxiety include:

  • Increased heart rate – anxiety triggers the release of stress hormones like adrenaline, which can cause the heart to beat faster than usual. This increase in heart rate is the body’s way of preparing for a perceived threat or danger.
  • Elevated blood pressure – the increase of adrenaline and other stress hormones can also cause blood vessels to constrict, leading to a temporary rise in blood pressure. Over time, chronic anxiety and stress can contribute to long-term hypertension, which is a risk factor for heart disease and stroke.
  • Irregular heartbeat (arrhythmia) – in some cases, severe anxiety or panic attacks can lead to irregular heart rhythms or palpitations. While these are often harmless, frequent or severe arrhythmias may require medical attention.
  • Increased risk of heart disease – prolonged exposure to stress and anxiety can contribute to the development of heart disease over time. Chronic stress may promote inflammation in the body, which is associated with hardening of the arteries and other cardiovascular conditions.
  • Reduced blood flow to the heart – during periods of intense anxiety, blood flow may be redirected away from non-essential organs, including the digestive system. This happens to prioritise oxygen delivery to the muscles and brain. This can sometimes result in reduced blood flow to the heart, potentially triggering chest pain or other cardiac symptoms.
  • Impact on blood clotting – stress and anxiety can influence blood clotting factors, potentially increasing the risk of blood clots forming in the arteries or veins. This can be particularly concerning for people with pre-existing cardiovascular conditions or a history of blood clots.
  • Worsening of existing cardiovascular conditions – for people with pre-existing heart conditions such as coronary artery disease or heart failure, anxiety can exacerbate symptoms and increase the risk of complications.
Respiratory Changes

Respiratory Changes

Anxiety can lead to various physiological changes in the body, including respiratory changes. Respiratory changes occur due to the activation of the body’s stress response system, primarily involving the sympathetic nervous system and the release of stress hormones like adrenaline and cortisol. 

One common respiratory change during anxiety is hyperventilation. This is where breathing becomes rapid and shallow and this happens because the body perceives that there is a threat or danger, and as a result, the sympathetic nervous system is activated. This leads to an increase in breathing rate to prepare the body for fight-or-flight response, supplying more oxygen to muscles and organs. 

Anxiety can also cause sensations of chest tightness or discomfort. This might be due to muscular tension in the chest area as a result of stress or the body’s attempt to increase oxygen intake rapidly through shallow breathing. The autonomic nervous system regulates involuntary bodily functions, including breathing. During anxiety, this system can become overactive, leading to irregularities in breathing patterns such as shortness of breath, sighing, or feeling like you can’t take a deep breath. 

These respiratory changes are part of the body’s natural response to perceived threats or stressors. While they can be uncomfortable or distressing, understanding the underlying causes can help people manage and alleviate anxiety-related respiratory symptoms through techniques like deep breathing exercises, relaxation techniques, and cognitive behavioural therapy.

Gastrointestinal Distress

When you’re anxious or stressed, your body enters a state of heightened alertness, triggering the release of stress hormones like cortisol. These hormones can affect digestion by slowing down the emptying of the stomach and increasing stomach acid production, leading to symptoms like heartburn, indigestion and nausea. Some other ways anxiety can contribute to gastrointestinal issues include:

  • Altered gut motility – anxiety can also affect the muscles in your digestive tract, leading to changes in gut motility. Some people may experience diarrhoea or constipation during periods of high stress or anxiety.
  • Sensitivity to symptoms – anxiety can make you more attuned to physical sensations in your body, including those related to digestion. This heightened awareness can make normal digestive processes feel more intense or uncomfortable, leading to increased anxiety.
  • Microbiome disruption – chronic stress and anxiety may disrupt the balance of bacteria in the gut, known as the gut microbiome. An imbalance in the microbiome has been linked to various gastrointestinal disorders, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).
  • Behavioural factors – when feeling anxious, people may engage in behaviours that can exacerbate gastrointestinal symptoms, such as overeating or consuming unhealthy foods, skipping meals, or neglecting self-care practices like exercise.

Muscle Tension

Muscle tension is a common physical symptom experienced by people dealing with anxiety.  Anxiety triggers the fight-or-flight response. As part of this response, muscles tense up in preparation for action. Anxiety can lead to increased muscle activation, causing muscles to contract and tighten. This heightened muscle activity can lead to chronic muscle tension, especially in areas like the neck, shoulders and back. 

It’s essential for individuals experiencing significant muscle tension and anxiety to seek support from a healthcare professional.

Impact on the Immune System

Impact on the Immune System

Anxiety can have a significant impact on the immune system, primarily through the dysregulation of the body’s stress response mechanisms – the release of stress hormones such as cortisol and adrenaline. These stress hormones, when released in excess due to chronic anxiety, can suppress certain aspects of the immune system while simultaneously activating others. The suppression of the immune system can weaken the body’s ability to fight off infections and other illnesses. 

Some other ways that anxiety can impact on the immune system include:

  • Inflammation – chronic anxiety can lead to low-grade inflammation throughout the body. While inflammation is a normal response to infection or injury, chronic inflammation can contribute to various health problems, including autoimmune disorders and cardiovascular disease.
  • Alteration of immune cell activity – stress hormones can influence the activity of immune cells such as lymphocytes, natural killer cells, and macrophages. These alterations can affect the body’s ability to recognise and destroy harmful pathogens.
  • Impaired wound healing – anxiety-induced stress can impair the body’s ability to heal wounds efficiently. This effect is due to the dysregulation of inflammatory responses and the suppression of immune cell activity necessary for the healing process.
  • Increased susceptibility to illness – people experiencing chronic anxiety may be more susceptible to infections such as colds, flu and other viral illnesses. Additionally, they may experience more severe symptoms and longer recovery times compared to those without chronic anxiety.
  • Exacerbation of autoimmune disorders – chronic stress and anxiety can exacerbate symptoms of autoimmune disorders such as rheumatoid arthritis, lupus and inflammatory bowel disease. This is due to the dysregulation of the immune system, which can lead to increased inflammation and tissue damage.

Skin and Hair Reactions

Anxiety can manifest in various physical ways, including affecting the skin and hair. Some common skin and hair problems that can be exacerbated by anxiety include:

  • Acne – stress and anxiety can trigger hormonal fluctuations that may lead to acne breakouts. Stress can exacerbate existing acne by increasing inflammation in the body.
  • Eczema and psoriasis – anxiety can exacerbate skin conditions like eczema and psoriasis, leading to flare-ups and increased itching and irritation.
  • Hair loss – chronic stress and anxiety can cause stress hormones to disrupt the hair growth cycle, leading to shedding and hair loss.
  • Dry skin and scalp – stress can impair the skin’s barrier function, leading to increased water loss and dryness. This can result in dry, flaky skin and scalp.
  • Hives and rashes – anxiety can trigger the release of histamine in the body, leading to allergic reactions such as hives or rashes.
  • Hair pulling (trichotillomania) – in some cases, anxiety can contribute to compulsive behaviours like hair pulling, known as trichotillomania. This can result in noticeable hair loss and bald patches.
  • Increased sensitivity – anxiety can heighten the body’s sensitivity to various stimuli, leading to increased skin sensitivity and reactivity.
Cognitive Impairment

Cognitive Impairment

Cognitive impairment due to anxiety can happen in various ways and can affect different aspects of cognitive functioning. While anxiety is primarily associated with emotional and psychological distress, it can also impact cognitive processes such as attention, concentration, memory and decision-making. Anxiety can make it difficult to focus on tasks affecting attention span. People experiencing anxiety may find themselves easily distracted by worrying thoughts or physical sensations associated with anxiety, making it challenging to concentrate generally.

Anxiety can also affect cognitive functioning in other ways including:

  • Memory – anxiety can interfere with both short-term and long-term memory. People may have difficulty remembering information, such as details of conversations or events, due to heightened stress levels affecting memory encoding and retrieval processes.
  • Problem-solving and decision-making – anxiety can impair cognitive flexibility and problem-solving abilities. When feeling anxious, people may struggle to generate effective solutions to problems or make decisions, as their thinking may be clouded by worry or fear.
  • Processing speed – anxiety can slow down cognitive processing speed, meaning that it can take longer for people to understand information. This can impact performance on tasks that require quick thinking or rapid information processing.
  • Working memory – working memory, which involves holding and manipulating information in the mind over short periods, can be negatively affected by anxiety. People may find it harder to juggle multiple pieces of information simultaneously, leading to difficulties in tasks that require multitasking or complex cognitive operations.
  • Executive functioning – anxiety can disrupt executive functions such as planning, organising and self-regulation. This can result in difficulties in setting goals, prioritising tasks and managing time effectively.
  • Verbal fluency – some people may experience difficulties in finding the right words or expressing themselves verbally when experiencing anxiety. This can impact communication skills and lead to feelings of frustration or inadequacy.

Everybody experiences anxiety from time to time; however, it is important to be able to recognise the signs of anxiety disorder. Some common signs may include:

  • Restlessness – being unable to relax, feeling on edge, or being easily startled.
  • Fatigue – feeling tired despite getting enough rest.
  • Tension in the muscles – persistent muscle tension, especially in the neck, shoulders and jaw.
  • Sleep disturbances – difficulty falling asleep or staying asleep, or experiencing restless sleep.
  • Sweating – excessive sweating or cold, clammy hands.
  • Trembling – shaking or trembling uncontrollably.
  • Experiencing gastrointestinal issues – stomach aches, nausea, diarrhoea or other digestive problems.
  • Excessively worrying – constantly and excessively worrying about everyday events or situations.
  • Irritability – feeling easily annoyed or irritated.
  • Difficulty concentrating – having difficulty focusing.
  • Worrying about the future – persistent fear or apprehension about the future, including what may or may not happen.
  • Avoidance – avoiding certain situations or places due to fear or anxiety.
  • Panic attacks – sudden and intense episodes of fear or terror, which can be accompanied by physical symptoms like chest pain, shortness of breath, or feeling dizzy.
  • Perfectionism – this can include setting extremely high standards for yourself and being overly self-critical.
  • Experiencing social isolation – withdrawing from social activities or avoiding social situations altogether.
  • Having difficulty with relationships – you may be struggling to maintain healthy relationships due to feelings of anxiety.
  • Feeling excessively self-consciousness – being overly concerned about how you are being perceived by others.

If you feel that you have symptoms of anxiety disorder or if you are struggling with your mental health at all, you should see your GP. 

If you have been diagnosed with an anxiety disorder, the NHS may offer you self-help methods, talking therapies or medication. 

Talking therapies include:

  • Cognitive behavioural therapy (CBT) – CBT is a type of talking therapy that helps you to understand the link between your thoughts, feelings and behaviour. It can help you to find ways to overcome your anxiety by challenging your negative thought patterns and beliefs. CBT is evidence-based and has been found to be effective for many mental health conditions, including anxiety disorders, depression and post-traumatic stress disorder (PTSD).
  • Exposure therapy – this type of therapy is particularly useful for someone who has specific phobias and certain types of anxiety disorders. Exposure therapy involves gradually facing and confronting the phobia, allowing people to become less sensitive to whatever is causing anxiety.
  • Mindfulness-based therapies – mindfulness-based approaches, such as mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT), teach people to be present in the moment and develop a non-judgemental awareness. These techniques can be beneficial for managing anxiety. When we become more aware of the present moment, this can help us to enjoy the world around us more and understand ourselves and other people better. When we become more aware of the present moment, we can sometimes appreciate things that we were taking for granted and find beauty in everyday experiences.

You may also be offered medication to help manage your anxiety. Some common medications for anxiety include:

  • Selective serotonin reuptake inhibitors (SSRIs) – these are antidepressants which are used to treat anxiety. Sertraline is the most commonly used to treat anxiety.
  • Beta-blockers – these can help with the physical signs of anxiety. They can help to lower a fast heartbeat and reduce shaking.
  • Benzodiazepines – these should only be prescribed if your anxiety is extreme or if you are in crisis as they are addictive and they become less effective if they are used long term.

Some useful contacts if you are struggling with anxiety are:

Anxiety UK 

Social Anxiety UK

No Panic UK

By addressing both the psychological and physiological aspects of anxiety, we can strive towards promoting holistic well-being and enhancing the quality of life for those affected.

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About the author

Claire Vain

Claire Vain

Claire graduated with a degree in Social Work in 2010. She is currently enjoying her career moving in a different direction, working as a professional writer and editor. Outside of work Claire loves to travel, spend time with her family and two dogs and she practices yoga at every opportunity!



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