Dysautonomia Explained: Why Heart Rate, Blood Pressure and Digestion Go Haywire in ME/CFS and Long Covid

A racing heart on standing up, nausea after eating, constantly cold hands and feet even in a warm room – people living with ME/CFS or Long Covid often know a whole collection of seemingly unrelated complaints like these. In fact, they frequently share a common root: an autonomic nervous system that has fallen out of sync. This is known as dysautonomia. This article explains what lies behind it – without claiming that every symptom can be explained by it, and without replacing medical assessment.

What the autonomic nervous system actually does

The autonomic nervous system (ANS) is a kind of autopilot for the body. It controls everything that normally happens without our conscious involvement: heart rate, breathing and the width of blood vessels are part of this, as are digestion, sweating, bladder function and body temperature. Anatomically, the ANS is a complex network of brain, spinal cord and peripheral nerves, broadly divided into two opposing branches: the sympathetic branch, which activates the body ("fight or flight"), and the parasympathetic branch, responsible for rest, recovery and digestion ("rest and digest"). In a healthy state, both systems alternate in finely tuned response to the situation, without us having to consciously do anything. When this interplay is disrupted – for example because one branch responds too strongly or too weakly, or because both are no longer active at the right moment – this is called dysautonomia. It is not a single illness but an umbrella term for very different forms of autonomic dysregulation that can affect many different organ systems at once. Basic terms around such diagnoses are also summarised clearly in the Glossary of Long Covid, ME/CFS and POTS.

Dysautonomia in ME/CFS and Long Covid: a recurring pattern

Autonomic dysregulation is not a footnote in Long Covid and ME/CFS but a central and well-documented phenomenon. A review describes autonomic nervous system dysfunction as a key clinical and neurological overlap between ME/CFS and Long Covid, in which the ANS controls the heart, gut and bladder via sympathetic and parasympathetic pathways. A study on the clinical characterisation of dysautonomia in Long Covid patients also points to possible causes under discussion, including nerve involvement caused by the virus, tissue oxygen deficiency and inflammatory processes – though the exact mechanisms have not yet been conclusively established. That this topic has now reached large-scale research is shown by the RECOVER initiative of the US National Institutes of Health: it has launched clinical trials to investigate treatment approaches for autonomic nervous system dysfunction in Long Covid – an indication of how seriously this symptom area is now being taken, even though robust, everyday treatment recommendations are still a thing of the future.

Heart and circulation out of sync

The best-known effect is on the cardiovascular system: on standing up, the body is normally supposed to automatically adjust heart rate and vascular tone so that enough blood reaches the brain. When this regulation is disrupted, it can lead to a racing heart, dizziness or near-fainting – phenomena that are particularly pronounced in POTS (postural orthostatic tachycardia syndrome). How this shows up in everyday life, and what happens during a medical stand test, is described in detail in the article "Understanding POTS".

Digestion in a state of emergency

Less in the spotlight, but just as burdensome for many affected people: digestion. Since the parasympathetic branch of the ANS regulates bowel activity, dysautonomia can lead to slowed or irregular passage through the gastrointestinal tract. This can show up as a feeling of fullness after small meals, nausea, bloating, changing bowel habits, or a sense that the stomach has "come to a standstill". Such symptoms are often treated in isolation as a standalone digestive problem – yet they can be part of the same autonomic pattern that also affects heart rate and blood pressure. This makes it important not to jump to conclusions about symptoms, but to have them medically assessed.

Temperature, bladder, pupils: the quiet symptoms

Temperature regulation, sweat production, bladder function and even pupil response also depend on the autonomic nervous system. This explains why some people affected are constantly cold or sweating even though the room temperature hasn't changed, or why light sensitivity and altered thirst can occur. Viewed individually, these symptoms often seem trivial or unrelated – but in the context of dysautonomia, they form a more coherent picture.

What this means for pacing and everyday life

A disrupted autonomic regulation means that the body often responds disproportionately strongly or inappropriately to stimuli such as standing up, eating, heat or stress – and then only calms down slowly afterwards. This is one of the reasons why exertion is so hard to predict in ME/CFS and Long Covid, and why small everyday actions can sometimes feel like major efforts. Anyone wanting to learn the basic principles of energy management will find a good starting point in the article "Pacing Basics: What Pacing Is and Why It Helps with PEM". Since autonomic responses often fluctuate, looking at your own heart rate variability can also help identify patterns – more on this in the article "Understanding Heart Rate Variability (HRV)".

It's important to note: dysautonomia is a medical description, not a self-diagnosis. A racing heart, persistent digestive complaints or circulatory problems should always be medically assessed to rule out other causes and, if appropriate, to arrange targeted tests such as a stand test. mypacing can help make your own everyday patterns more visible, but it does not replace diagnosis or treatment by medical professionals.

Sources

• Autonomic Nervous System (ANS) Dysfunction in Long Covid and in ME/CFS
• Clinical characterization of dysautonomia in long COVID-19 patients
• NIH opens long COVID trials to evaluate treatments for autonomic nervous system dysfunction
• Dysautonomia | Autonomic Nervous System Disorders
• Dysautonomia International: Basics of the Autonomic Nervous System