Doctor explains: Brain Fog and Sound Sensitivity: Neurological Strategies to Calm a Hyper-Reactive Nervous System
Updated: Aug 30
Brain fog and sensitivity to sound are surprisingly common in people living with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), Long COVID and some people with fibromyalgia. For some, ordinary background noise can become exhausting. A conversation, television, traffic or several people speaking at once may suddenly feel overwhelming.
These symptoms can be particularly difficult to understand because routine neurological examinations and standard blood tests may be normal.
As an ME/CFS specialist, I often discuss brain fog and sensory sensitivity with patients. One important point is that these symptoms are not simply a matter of "not concentrating hard enough". They can form part of a wider pattern of neurological and sensory dysfunction, often made considerably worse by Post-Exertional Malaise (PEM).
Post-Exertional Malaise (PEM) and sensory overload
Post-Exertional Malaise (PEM) is one of the most important features of ME/CFS. It describes a worsening of symptoms after physical, cognitive, emotional or sensory exertion.
Importantly, exertion is not limited to exercise.
For someone with ME/CFS, concentrating on a complicated task, having a long conversation, attending a busy environment or dealing with loud sounds can all contribute to the overall energy demand on the body.
During Post-Exertional Malaise (PEM), people may experience:
Increased brain fog
Difficulty finding words
Problems concentrating or processing information
Increased sensitivity to sound or light
Headaches or dizziness
Greater fatigue and weakness
Sleep disturbance
Increased pain
A feeling of being overwhelmed by normal surroundings
This is one reason why a person who appears to cope reasonably well one day may struggle significantly the next.
Post-Exertional Malaise (PEM): why does sound suddenly feel unbearable?
People sometimes describe sound sensitivity as if their "volume control has been turned up".
There may be no problem with the ears themselves. Instead, the difficulty may involve how the nervous system processes and filters incoming information.
Normally, the brain constantly decides which sensory signals require attention and which can be ignored. In a busy room, for example, you can usually concentrate on one person's voice while filtering out background conversations.
When someone is experiencing significant fatigue, brain fog or Post-Exertional Malaise (PEM), this filtering process may become much more difficult.
The result can be a sense that every sound is demanding attention simultaneously.
This can contribute to sensory overload, particularly when combined with bright lights, movement, conversation, smells or other stimulation.
Post-Exertional Malaise (PEM) and the "brain fog" connection
Brain fog is not a medical diagnosis in itself, but it is a very real symptom reported by most people with ME/CFS and Long COVID.
Patients may describe:
Forgetting familiar words
Losing their train of thought
Difficulty reading
Needing more time to understand information
Difficulty following conversations
Poor short-term memory
Feeling mentally "slow"
Difficulty making decisions
For some people, brain fog becomes substantially worse after activity and improves when they reduce demands.
This relationship with Post-Exertional Malaise (PEM) is clinically important.
Rather than treating brain fog as an isolated symptom, an ME/CFS specialist will usually consider it as part of the wider pattern of symptoms, activity tolerance, sleep, pain, autonomic symptoms and PEM.
Post-Exertional Malaise (PEM): reducing sensory demands
One of the most useful strategies is not to try to "train" yourself to tolerate increasing levels of stimulation.
Instead, the aim is to understand your limits and reduce unnecessary sensory demands.
This can include:
Creating a quieter environment
If background noise is exhausting, consider spending more time in quieter rooms. Turning off unnecessary television or radio can make a surprising difference.
Using headphones carefully
Noise-reducing or noise-cancelling headphones may help some people, particularly in unavoidable noisy environments. However, they should be used as a tool rather than a requirement to block all sound continuously.
Reducing competing information
Trying to read an email while listening to television and having a conversation may be much harder than doing each task separately.
Reducing multitasking can lower cognitive demand.
Planning recovery periods
If a busy environment cannot be avoided, building in quiet recovery time afterwards may help reduce the risk of worsening symptoms and Post-Exertional Malaise (PEM).
Post-Exertional Malaise (PEM): pacing cognitive activity
Pacing is not simply about how many steps you walk.
For people with ME/CFS, cognitive activity can be just as important.
A useful approach is to identify activities that repeatedly trigger worsening symptoms. These might include:
Long video calls
Extended computer work
Reading complicated documents
Shopping in busy environments
Driving
Social gatherings
Prolonged conversations
Try breaking demanding activities into smaller sections, with rest or low-stimulation periods between them.
The goal is to stay within your available energy rather than repeatedly exceeding it and triggering Post-Exertional Malaise (PEM).
Post-Exertional Malaise (PEM) and calming the nervous system
There is growing interest in how the autonomic nervous system and brain-body signalling may contribute to symptoms in ME/CFS and Long COVID.
Some patients find gentle techniques such as slow breathing, relaxation exercises, mindfulness or spending time in a quiet environment helpful.
These approaches should not be presented as a cure for ME/CFS.
Instead, they may help some people manage the additional stress and sensory stimulation associated with symptoms.
If a breathing exercise makes you feel dizzy, uncomfortable or worse, stop. There is no need to force yourself through it.
Post-Exertional Malaise (PEM): when should you seek specialist assessment?
Persistent brain fog and sound sensitivity can have many possible causes. ME/CFS is only one possibility.
A medical assessment may be appropriate when symptoms are persistent, disabling, unexplained or associated with characteristic Post-Exertional Malaise (PEM).
An online ME/CFS doctor can take a detailed history of symptom patterns, activity tolerance and previous investigations. This can be particularly useful for people who find travelling to appointments difficult because of PEM.
Specialist assessment may also be relevant for someone experiencing persistent fatigue and cognitive symptoms after an infection. A Long COVID fatigue clinic or post viral fatigue doctor may be able to help determine whether the overall pattern is consistent with Long COVID, ME/CFS or another condition.
Similarly, people with widespread pain, fatigue, poor sleep and sensory symptoms may benefit from assessment by a fibromyalgia specialist online, particularly where ME/CFS and fibromyalgia may overlap.
Post-Exertional Malaise (PEM), ME/CFS testing and current research
There is currently no single universally accepted blood test that can diagnose ME/CFS in routine clinical practice. Diagnosis remains primarily clinical, supported by appropriate investigations to consider other causes of symptoms.
However, ME/CFS research is progressing rapidly.
Researchers are investigating immune function, metabolism, autonomic nervous system regulation, inflammation, genetics and epigenetic changes. New approaches to ME/CFS testing are also being investigated, including blood-based biomarkers and molecular signatures.
These developments are important because better testing could eventually help doctors understand different biological subgroups of ME/CFS and identify more targeted treatments.
At the same time, patients should be cautious about commercial tests or therapies advertised as proven cures. ME/CFS therapy should be based on an individual's symptoms, risks, functional capacity and the best available evidence.
Post-Exertional Malaise (PEM): the key message
Brain fog and sound sensitivity are not simply signs that someone is "not trying hard enough".
When they occur alongside Post-Exertional Malaise (PEM), fatigue, sleep problems, pain, autonomic symptoms and other features of ME/CFS, they can form part of a complex illness affecting multiple systems.
The most useful approach is often to understand your individual triggers, reduce unnecessary sensory and cognitive demands, and avoid repeatedly exceeding your limits.
If symptoms are persistent or disabling, a specialist assessment can help put the whole picture together rather than treating each symptom in isolation.
For information about assessment and management, you can explore our ME/CFS and related conditions blog or book an online consultation. You can also learn more about Prof. Dmitry Pshezhetskiy and his clinical and research work.
If you would like specialist assessment, learn more about our online consultations.
Prof. Dmitry Pshezhetskiy, MBBS, PhD, MRCGP
GMC 7494518 — Registered Medical Practitioner (GP)
Medical Disclaimer: The information provided in this article is for general educational and informational purposes only and does not constitute personalized medical advice, formal diagnosis, or treatment planning. Reading this content or communicating via this website does not establish a doctor-patient relationship with Prof Dmitry Pshezhetskiy. ME/CFS affects every individual differently; strategies discussed may not be suitable or safe for your specific health situation. Always consult your GP, specialist healthcare team, or NHS 111 regarding your personal medical concerns. In a medical emergency, please dial 999 or visit your nearest Emergency Department immediately. For a full disclaimer, see Medical Disclaimer & Terms of Use in Terms and Conditions on the policies page.
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