Fatigue, brain fog, or heart palpitations after Covid? Learn what Long Covid is, why symptoms persist, and how the nervous system may be key to it all.

Have you been stuck in a cycle of symptoms without clear answers? Fatigue. Brain fog. Dizziness. Heart palpitations.

Maybe you’ve done every test your doctor can think of and they’ve all come back clear. Perhaps you’re even told it’s “just anxiety.”

If these symptoms began after a Covid infection, you might be dealing with Long Covid. 

What is Long Covid?

Long Covid, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), is the term used when symptoms continue for weeks or months after the initial Covid infection.

According to the World Health Organisation1, Long Covid is generally defined as symptoms that:

• Start within three months of the initial infection

• Last for at least two months

• Cannot be explained by another diagnosis

It can affect people who had severe illness as well as those who only experienced mild or even asymptomatic infections.

What are the symptoms of Long Covid?

Long Covid doesn’t look the same for everyone. In fact, more than 200 different symptoms have been reported, and they often fluctuate or change over time. 

Some of the most common symptoms of Long Covid include2:

• Fatigue that doesn’t improve with rest

• Brain fog (including difficulty concentrating, remembering, or finding words)

• Shortness of breath 

• Heart palpitations or rapid heart rate

• Dizziness or lightheadedness (sometimes linked to POTS)

• Sleep disturbances

• Muscle aches and joint pain

• Digestive issues

• Heightened sensitivity to noise or light

• Anxiety and low mood (often as a result of the ongoing illness)

For some people, these symptoms come and go. For others, they remain constant, affecting daily life, work, and relationships.

Why does Long Covid happen?

Researchers are still piecing this puzzle together, but at Freeme, we believe there’s one overlooked part of the puzzle: the nervous system.

Your autonomic nervous system (ANS) acts like the body’s autopilot, quietly regulating everything you don’t have to think about: heart rate, blood pressure, breathing, digestion, and temperature. It has two main branches:

• The sympathetic system, which works like the accelerator, triggering fight-or-flight and speeding things up: faster heart rate, higher blood pressure, sharper alertness.

• The parasympathetic system, which works like the brake, helping the body slow down, rest, digest, and repair.

In a healthy system, these two branches are constantly balancing one another, shifting smoothly depending on what the body needs. But after a major stressor like Covid, this delicate balance can be thrown off3,4. 

This is because the body’s “threat detection system” stays switched on even after the infection has passed. Imagine a smoke alarm that keeps blaring even when the fire is out. The result is an ANS that is stuck in high alert.

When this happens, the sympathetic branch can dominate, keeping the body in fight-or-flight mode. The parasympathetic “rest and repair” branch struggles to kick in. This imbalance can leave the entire system hypersensitive, meaning the heart races at small triggers, breathing feels shallow, digestion slows, and sleep feels light and unrefreshing.

It explains why symptoms can show up across so many different systems of the body, because the nervous system is so far reaching.