Introduction

Almost everyone feels tired from time to time. But when fatigue becomes persistent, overwhelming, and unrelieved by rest, it’s no longer just being “run down.” This is what we often describe in medicine as chronic fatigue.

Chronic fatigue is not simply about being tired. It is a medical condition that can stem from a variety of underlying causes—ranging from hormonal imbalances to mitochondrial dysfunction—and it can severely impact quality of life.

As a clinician, I often see patients who have been told their fatigue is “just stress” or “in their head.” In reality, fatigue is a symptom—and our job is to figure out what the body is signaling.

In this article, I’ll break down what chronic fatigue is, the medical and functional approaches to diagnosis, and strategies for treatment that can help patients reclaim energy and restore function.

What Is Chronic Fatigue?

Chronic fatigue refers to a state of prolonged, unexplained tiredness lasting for at least 6 months. It may worsen with physical or mental activity and is not relieved by sleep.

Some patients may meet criteria for chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), which includes additional features such as:

• Post-exertional malaise (worsening of symptoms after activity)
• Unrefreshing sleep
• Brain fog and difficulty concentrating
• Muscle and joint pain
• Dizziness or orthostatic intolerance

But many patients experience chronic fatigue without meeting full CFS criteria, often related to underlying metabolic, hormonal, or inflammatory issues.

Common Causes of Chronic Fatigue

Fatigue is multifactorial, and it’s rarely caused by just one issue. As a clinician, I look at several key systems that can contribute to energy depletion:

1. Sleep Disorders

• Sleep apnea: Interrupted breathing leads to low oxygen and poor sleep quality.
• Insomnia: Difficulty falling or staying asleep.
• Restless leg syndrome: Nighttime leg movements fragment sleep.

2. Hormonal Imbalances

• Low thyroid function (hypothyroidism)
• Adrenal dysfunction (cortisol imbalance)
• Low testosterone or estrogen imbalances
• Insulin resistance and blood sugar fluctuations

3. Mitochondrial Dysfunction

Mitochondria are the power plants of our cells. When they’re damaged—by chronic illness, toxins, infections, or aging—energy production (ATP) drops, leading to fatigue.

4. Infections and Immune Dysregulation

• Chronic viral reactivation (e.g., Epstein–Barr virus)
• Lyme disease or post-tick illness
• Long COVID and post-viral syndromes

5. Nutritional Deficiencies

• Low vitamin D, B12, or folate
• Iron deficiency (with or without anemia)
• Magnesium or zinc deficiency

6. Gut Health and Dysbiosis

The gut plays a central role in energy metabolism and immune regulation. Overgrowth of harmful bacteria, leaky gut, or food sensitivities can drive fatigue through inflammation.

7. Inflammation and Autoimmunity

Chronic systemic inflammation—whether from autoimmune conditions or metabolic syndrome—burns through energy reserves and interferes with cellular repair.

8. Psychological and Environmental Factors

Depression, trauma, toxin exposure (such as mold or heavy metals), and chronic stress can all contribute to fatigue through both physiological and psychological pathways.

How We Diagnose Chronic Fatigue

When a patient presents with chronic fatigue, I start with a comprehensive evaluation. This often includes:

1. Detailed history and symptom mapping – When did fatigue begin? What makes it worse or better? Are there associated symptoms like brain fog, muscle pain, or weight changes?
2. Physical exam – Looking for thyroid enlargement, lymph node swelling, neurological changes, or other physical signs.
3. Laboratory testing – Key labs often include:
   • Thyroid function (TSH, free T3, free T4, reverse T3)
   • Vitamin and mineral status (B12, folate, vitamin D, iron panel)
   • Inflammatory markers (CRP, ESR)
   • Hormonal panels (cortisol, testosterone, estrogen, DHEA)
   • Fasting insulin and glucose levels
4. Specialized testing (when indicated) – Sleep studies, mitochondrial function testing, microbiome analysis, or viral antibody panels.

The goal is always to identify the root cause, not just label the symptom.

Treatment Strategies for Chronic Fatigue

Treatment depends on the underlying drivers. While no two patients are identical, here are some of the strategies I use clinically:

Lifestyle Foundations

• Sleep hygiene: Regular sleep schedule, dark/cool room, limiting screens before bed.
• Nutrition: Anti-inflammatory diet, rich in whole foods, omega-3s, and antioxidants. Limiting processed foods and refined sugars.
• Movement: Gentle exercise such as walking, yoga, or resistance training to support circulation and mitochondrial function.
• Stress reduction: Meditation, breathing exercises, and mindfulness practices.

Medical and Functional Interventions

1. Address sleep disorders – CPAP for sleep apnea, iron for restless legs, cognitive behavioral therapy for insomnia.
2. Correct deficiencies – B12 injections, vitamin D supplementation, magnesium glycinate, zinc.
3. Hormone optimization – Thyroid hormone replacement, testosterone support, or cortisol balancing strategies.
4. Mitochondrial support – Supplements such as CoQ10, PQQ, NAC, and acetyl-L-carnitine. Red light therapy and PEMF can also support cellular energy.
5. Gut healing – Probiotics, prebiotics, and targeted antimicrobial protocols to rebalance the microbiome.
6. Anti-inflammatory therapies – Omega-3s, curcumin, and dietary changes to reduce systemic inflammation.
7. Infection treatment – Antivirals, antimicrobials, or immune-modulating therapies when chronic infection is identified.

The Role of Functional Medicine

Chronic fatigue is rarely solved with a single prescription. That’s why a functional medicine approach—looking at the interconnected systems of the body—often brings the best results.

By addressing mitochondrial health, gut function, hormonal balance, and inflammation simultaneously, patients often experience steady improvements in energy and resilience.

Practical Steps If You Struggle With Chronic Fatigue

If you’re experiencing chronic fatigue, here’s where to start:

1. Keep a symptom journal – Track sleep, energy, diet, and activity patterns.
2. Rule out obvious medical conditions – Thyroid disease, anemia, and diabetes are common contributors.
3. Prioritize rest – Don’t push through severe fatigue; it often makes symptoms worse.
4. Consider lab testing – A comprehensive workup can uncover hidden deficiencies or imbalances.
5. Start small changes – Consistent sleep, hydration, whole-food nutrition, and gentle movement are foundations of recovery.

Final Thoughts

Chronic fatigue is not a sign of weakness or simply “being out of shape.” It is a medical condition with real biological underpinnings that deserves thorough evaluation and treatment.

With the right clinical approach—combining medical evaluation, functional strategies, and personalized care—patients can experience meaningful improvements in energy, cognition, and quality of life.

If fatigue has taken over your life, know that there are answers. You don’t have to live exhausted.

‍