What is long covid?

What is long covid and how is it related to the autonomic nervous system

What is the reason I have fatigue, palpitations, shortness of breath, insomnia, and anxiety in long Covid? What is autonomic dysfunction in long Covid? A long-hauler’s Covid recovery story.

In this blog, Dr Boon Lim, consultant cardiologist and the clinical lead for the Imperial syncope diagnostic unit based at Hammersmith Hospital London, writes about his experience seeing patients who have developed a multitude of varied symptoms, which are likely to be as a direct result of autonomic dysfunction in the post Covid recovery phase (aka long Covid or long-haulers). Click here for PDF .

The initial experience gained from performing tilt table testing on the initial cohort of patients coming through with a wide ranging group of symptoms, illustrated some of the physiology which underscores some of the varied symptoms in the long Covid including:

  • shortness of breath
  • palpitations
  • chest pain
  • fatigue
  • insomnia
  • temperature dysregulation
  • reflux and diarrhoea/constipation

The preliminary findings from the initial five patients undergoing tilt table testing were published on 1 January 2021 in an article, freely accessible on the link below:



Since this initial observation, many more patients have come through the Imperial tilt service, whose clinical presentation a very similar, with almost identical tilt table test findings, as can be seen in the article referenced above.

In summary, it is believed that some of the multiple symptoms which appear to be coming from different organ systems may have an underlying basis rooted in dysfunction of the autonomic nervous system, triggered by Covid.


What is the autonomic nervous system?

The autonomic nervous system is the subconscious nervous system that controls all the bodily functions we do not normally have to think about on a day-to-day basis. This is in contrast to the somatic (or conscious) nervous system, which governs all our conscious efforts, for example moving your hand to pick up a pencil to write, or indeed walk or control your vocal chords to speak. In contrast, the autonomic nervous system controls our bodily functions that we don’t normally have conscious control over such as: heart rate, respiration rate, depth of breathing, temperature regulation, bowel movements, and sweating.

One can imagine the subconscious nervous system is being heavily influenced by emotions, and one example of this experience, is the feeling of rising butterflies in your chest prior to giving a speech, or a attending a job interview or sitting for an exam. One might also feel the need to urinate or defecate several minutes before such an important event, which underscores how important it is that any emotional state of nervous tension, can have a direct influence on bodily functions and influence heart rate control and bowel movement.

So how does Covid affect the autonomic nervous system?

We don’t really know is the honest answer! However we see parallels between infections triggering another very similar condition, termed postural orthostatic tachycardia syndrome (POTS) which is a form of autonomic dysfunction, with symptoms triggered typically after a stressful event or a chronic infection (which need not be Covid). In fact, POTS has been known by several other names over the years including Soldier’s heart, post-traumatic stress disorder, Da Costa Syndrome (named after an American Civil War Dr who noticed a very similar constellation of symptoms presenting in soldiers returning from the front line in the American Civil War in the mid-1800s), Vietnam war syndrome.


The physiology that has been seen during tilt table testing, and reported in the journal article above, is very similar to that seen in a patient with very mild POTS, but with the explanation of symptoms, being almost directly applicable to the explanation of symptoms seen in patients with mild POTS.

Essentially, if the group of symptoms that you experience, are significantly exacerbated by standing upright, and relieved by lying down, then you may well have a degree of orthostatic intolerance. Orthostasis is derived from a Greek word meaning to stand upright and the term orthostatic intolerance simply means inability to tolerate standing upright due to worsening symptoms.

One plausible explanation for this, is that Covid has somehow readjusted the body’s response to orthostasis, and instead of a healthy response, with anti-gravity mechanisms in play to immediately correct the pooling of blood in the lower limbs on immediate standing, a patient who has developed autonomic dysfunction after Covid, may no longer be able to readily recover their blood pressure when standing up and when the blood pools down into the lower limbs due to gravity.

As a result, the body’s reaction is to engage a very strong fright or flight response, which releases stress hormones including adrenaline and cortisol which serve to increase heart rate, increased vasoconstriction (squeezing the blood vessels to return pooled blood to the heart), which would normally help to combat the slight drop in BP one would expect with standing upright.

However in autonomic dysfunction, the fright or flight response is very much enhanced, and the adrenaline and cortisol responses are maintain throughout much of the day, which eventually lead to the multiple effects described above including shortness of breath, fatigue, palpitations, dizziness, and insomnia. Think of it this way. Your body is constantly on fright of flight mode and without the ability to wind down and relax, you continue to dial up the adrenaline and manifestly side-effect profile from having a heightened adrenaline state throughout the daytime, as well as the night time, which can impair sleep, despite feeling extremely fatigued.

So how do you know if you have autonomic dysfunction in long Covid?

The first thing to recognise and to try and figure out is whether or not your long Covid symptoms are caused by autonomic dysfunction. One strong clue could be that you symptoms are very much worse when you stand up and improved when you lie down, particularly when you’re elevate your feet, for example placing your feet on the armrest of your sofa whilst lying down. By doing this, you are effectively returning blood to your heart from your lower limbs with the help of gravity.

If you frequently feel symptoms worsen whenever you stand up, you may well have a phenomena of autonomic dysfunction post long Covid in the next steps are as follows:

  1. Measure your blood pressure and pulse rate was seated in standing upright. This can usually be done simply by using an upper arm blood pressure cuff and taking repeated measurements in both sitting and standing stages. For example take measurements on three occasions whilst seated one minute apart, and take a further five measurements whilst standing up over 5 minutes, with your legs at shoulder with apart, without fidgeting and standing still.
  2. Assess your symptoms while seated on standing upright, in conjunction with the blood pressure changes
  3. If your blood pressure is low normal at rest (ie less than 120/80) and your heart rate accelerates (for example 70 beats per minute at rest seated, increasing to 110 bpm while standing), associated with symptoms, you may well have a degree of autonomic dysfunction with the heart rate rise being a marker of the stress response being initiated purely by standing. In this scenario, the blood pressure can either be stable a baseline values or attend decrease or even increase slightly with your symptoms.
  4. Finally, lie down after five minutes and assess if your symptoms are improve shortly after you lie down, particularly if you elevate feet above chest height


Top tips for improving autonomic dysfunction in long Covid

If you do have autonomic dysfunction in long Covid, and in particular if you have in low (<100/70) or low-normal blood pressure(<120/80), and symptoms which worsen significantly on standing, then considered the treatment strategies as below:

  1. Increase fluid intake aiming for 2 ½ to 3 L a day
  2. increase salt intake aiming for 1 to 2 teaspoons a day
  3. Consider wearing compression stockings which should be lower limb compression to the thigh or abdomen (grade 2)
  4. Consider wearing abdominal binders – (google medical hernia binders), which help maintain constriction to return blood pooling from the abdomen and intestines back into the heart – this can be particularly useful for patients who develop significant symptoms after eating large carbohydrate meals.
  5. Consider performing mindfulness-based meditation approach
  6. Store your breathing down aiming for 5 to 6 second breath in, followed by a 5 to 6 second breath out, was calming the mind in expressing positive emotion (think of this is doing the opposite of preparing for that nerve-wrenching job interview public speech or and its associated physical symptoms)

Other useful resources

Finally we do advise you to check out the resources as outlined below. In particular observing other patient stories and having some common threads to know that you are not alone, and there is light at the end of this tunnel may give you hope and expectation of recovery as you understand more and more why you may be experiencing some of these varied symptoms from different organs which are all driven by a disorder in the autonomic nervous system, triggered by long Covid.

  • Webinars from our StopFainting Long Covid series
    • What is Long Covid?    https://youtu.be/-F__jZNGEz8
    • Why does Long Covid affect the blood pressure?      https://youtu.be/9VYqvXpizoI
    • Our tips for preventing long Covid, if you are suffering from Covid infection currently https://youtu.be/6VXbVAjKaVo
  • https://www.longcovid.org/resources/patients

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