5 Signs You Should Take a Chronic Fatigue Test

Samantha always prided herself on being the type of woman who could juggle it all—work, family, and her favorite weekend hikes. But somewhere along the way, her energy slipped away. It wasn’t just tiredness after a busy day. It was bone-deep exhaustion that no amount of sleep could shake. Friends suggested she was just “overdoing it” or “getting older,” but Samantha knew something more was at play.

If this sounds familiar, you might be wondering whether it’s time to dig deeper into your fatigue and take a chronic fatigue test. Below are five signs that it’s not just tiredness—it’s time to investigate.

Chronic Fatigue Sign #1 – Post-Exertional Malaise (PEM)

One of the hallmarks of chronic fatigue syndrome (CFS) is post-exertional malaise (PEM). This isn’t your typical tiredness after a workout. In fact, people with PEM often feel worse after any physical or mental exertion, and recovery can take days or even weeks. Imagine taking a walk around the block or focusing on a work project, only to find yourself in a full-blown crash of fatigue, brain fog, or even flu-like symptoms the next day. PEM is a critical sign that the body is not processing energy in a normal way. Studies show that over 90% of people with CFS report PEM as a core symptom .

If you’ve been noticing that even minor activity leads to disproportionate exhaustion or illness, it’s a clear red flag that your fatigue is far beyond ordinary.

Chronic Fatigue Sign #2 – Unrefreshing Sleep

Are you waking up feeling like you never slept at all? Unrefreshing sleep is a common but often overlooked sign that something more serious could be going on. No matter how many hours of shut-eye you get, the exhaustion stays with you. This isn’t just poor sleep; it’s as if your body can’t access the restorative benefits of rest. Research shows that over 80% of chronic fatigue patients experience non-restorative sleep.

For someone suffering from chronic fatigue syndrome, the problem isn’t just falling asleep but staying refreshed. Even after eight hours in bed, you can wake up feeling as if you pulled an all-nighter. This kind of relentless fatigue can be a major sign that your body is struggling to recover, no matter how much rest you give it.

Chronic Fatigue Sign #3 – Cognitive Difficulties aka: Brain Fog

Have you found yourself walking into a room and forgetting why you went there? Or maybe you struggle to find the right words in conversation or can’t focus on tasks the way you used to. This mental cloudiness, often called brain fog, is another key symptom of chronic fatigue syndrome. It can make it difficult to manage everyday tasks, and even the simplest activities can feel like mental marathons.

Studies have found that more than 70% of people with chronic fatigue syndrome report cognitive difficulties. This isn’t just a lapse in focus—it’s a pervasive and persistent issue that impacts daily life, from concentration to memory.

Chronic Fatigue Sign #4 – Joint and Muscle Pain Without Inflammation

If you’re experiencing joint and muscle pain but without the visible inflammation that comes with conditions like arthritis, it could be another clue pointing to chronic fatigue syndrome. The pain can be widespread and may feel like the flu, with aching muscles and tender joints, but without any swelling or redness.

This pain isn’t due to overuse or injury—it comes seemingly out of nowhere. Research suggests that 60-85% of people with chronic fatigue syndrome report experiencing muscle and joint pain. If you’re dealing with unexplained pain that doesn’t seem to fit with any other diagnosis, it could be time to look deeper.

Chronic Fatigue Sign #5 – Sensitivity to Light, Sound, or Temperature

Have you noticed that things like bright lights, loud sounds, or even mild changes in temperature bother you more than they used to?

Increased sensitivity to light, sound, and temperature is another under-discussed symptom of chronic fatigue syndrome. For some, the glare of a computer screen or the buzz of a crowded room becomes unbearable.

While this symptom might not scream “fatigue” to an outsider, it’s a sign that your nervous system is overwhelmed. Studies have shown that up to 50% of CFS patients report these heightened sensitivities. If your environment feels more irritating or draining than it used to, it’s another clue your body is out of sync.

What exactly is a Chronic Fatigue Test?

This is the part of the article where I tell you that there’s no single test that can definitively diagnose CFS. Diagnosing  CFS requires a careful process of ruling out other causes of fatigue and evaluating specific symptoms. The diagnosis usually begins with a general workup by a family doctor, followed by more specialized testing as necessary.

Here’s a breakdown of the tests commonly run in the workup for chronic fatigue syndrome, from the initial visit to more specific blood tests that might be ordered by specialists.

Initial Workup by a Family Doctor

When someone first presents with unexplained fatigue lasting more than six months, a family doctor will typically start with a general workup to rule out other potential causes. Common conditions like anemia, hypothyroidism, diabetes, infections, and autoimmune diseases often need to be excluded before CFS can be considered.

Here are the standard tests a family doctor might run:

1. Complete Blood Count (CBC)

A CBC is a common first step to check for infections, anemia, or other blood disorders that can cause fatigue. A low red blood cell count, for example, might point to anemia, while an elevated white blood cell count could suggest infection.

Source: Mayo Clinic, 2023.

2. Thyroid Function Tests (TFTs)

The thyroid gland plays a key role in metabolism and energy regulation. An underactive thyroid (hypothyroidism) can cause symptoms similar to CFS, such as fatigue, weight gain, and cold intolerance. A family doctor will typically run a TSH (thyroid-stimulating hormone) test, and if necessary, follow up with free T3 and free T4 levels.

Source: American Thyroid Association, 2023.

3. Basic Metabolic Panel (BMP)

A BMP checks for imbalances in electrolytes, blood glucose, and kidney function, all of which can contribute to fatigue. Dehydration, kidney disease, or poorly controlled diabetes could be revealed through abnormal BMP results.

Source: National Institutes of Health (NIH), 2023.

4. Liver Function Tests

Liver disease can also lead to significant fatigue. ALT (alanine aminotransferase) and AST (aspartate aminotransferase) levels help assess liver health.

Source: Cleveland Clinic, 2023.

5. Vitamin D and B12 Levels

Low levels of vitamin D or B12 can be common causes of fatigue. If a deficiency is found, supplementation can often alleviate symptoms.

Source: U.S. National Library of Medicine, 2023.

6. Inflammatory Markers (ESR, CRP)

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are general markers of inflammation in the body. Elevated levels may point to an inflammatory or autoimmune disorder rather than chronic fatigue syndrome.

Source: Cleveland Clinic, 2023.

More Specific Tests Run by Specialists

Once general conditions are ruled out, specialists such as rheumatologists, neurologists, or integrative health practitioners might be consulted to order more specific tests for CFS.

1. Natural Killer (NK) Cell Function Test

Research has shown that people with CFS often have reduced NK cell activity, which is a marker of impaired immune system function. This test is not routine in primary care but is often used by specialists to assess immune dysfunction in CFS patients.

Source: Journal of Translational Medicine, 2022.

2. Cortisol Levels and Adrenal Function

Adrenal dysfunction, including low cortisol production, has been observed in some people with CFS. A salivary cortisol test (which measures cortisol levels at different times of the day) or a 24-hour urine cortisol test can provide insight into adrenal function.

Source: Journal of Clinical Endocrinology and Metabolism, 2021.

3. Viral Antibody Testing

Many cases of CFS follow viral infections. Tests for Epstein-Barr virus (EBV), Cytomegalovirus (CMV), and Human Herpesvirus 6 (HHV-6) antibodies are sometimes done, especially if there is a suspicion of viral reactivation.

Source: Annals of Internal Medicine, 2022.

4. Lactic Acid Testing

Lactic acid buildup can result from poor mitochondrial function, a feature observed in some patients with CFS. Elevated lactic acid levels after light activity might indicate impaired energy production at the cellular level.

Source: Journal of Clinical Pathology, 2021.

5. Sleep Studies

While not a blood test, a polysomnography (sleep study) can help determine if the fatigue is related to an underlying sleep disorder like sleep apnea, which could mimic CFS symptoms.

Source: National Sleep Foundation, 2023.

Diagnosing chronic fatigue syndrome is not a simple process—it involves ruling out other potential causes and looking closely at your specific symptoms. A comprehensive workup begins with standard tests run by your family doctor and can be expanded with more specialized testing by experts familiar with CFS. These tests not only help in confirming a diagnosis but can also reveal potential coexisting conditions like CIRS, which may require a different treatment approach.

Could It Be Something Other than Chronic Fatigue?

If you’re nodding along with any of these signs, it might be time to take a chronic fatigue test. But there’s more: these symptoms could also point to a deeper issue like Chronic Inflammatory Response Syndrome (CIRS), a condition that’s often misdiagnosed as chronic fatigue syndrome. CIRS can present with many of the same symptoms, including unrefreshing sleep and cognitive difficulties, but it’s caused by exposure to biotoxins such as mold. At Flourish Clinic, we specialize in identifying the root causes of your chronic fatigue and can help you determine if CIRS might be the culprit.

CIRS and Chronic Fatigue Testing

If there’s suspicion of Chronic Inflammatory Response Syndrome (CIRS) as a possible underlying cause, specific tests may be done, such as the Visual Contrast Sensitivity (VCS) test, genetic HLA-DR typing, and innate immune system inflammatory markers to measure chronic inflammation. At Flourish Clinic, we often see CIRS masquerading as chronic fatigue, especially in patients exposed to biotoxins like mold.

Source: Surviving Mold, 2020.

Chronic fatigue syndrome is more than just being tired—it’s a complex, life-altering condition that deserves serious attention. If you’re experiencing these five symptoms, it’s time to take action. Whether it’s chronic fatigue syndrome, CIRS, or something else, the key is to get the right diagnosis and start a path toward healing.

Have you experienced any of these signs? Could it be more than just fatigue?