The Top 5 Causes of Chronic Fatigue

We’ve all had days where we feel drained after poor sleep, a stressful week, or an illness. But when fatigue becomes a daily struggle—lasting for weeks, months, or even years—it’s often a sign that something deeper is going on. At Sheen Vein & Cosmetics in St. Louis, many of our patients come to us with the same frustration: “I’m always tired, and no one can tell me why.”

That’s where a functional medicine approach can make a difference. Rather than just masking symptoms with caffeine or medications, we look for the root causes of fatigue. Here are the top five causes of chronic fatigue that we see most often in our clinic.

1. Mitochondrial Dysfunction

Your mitochondria are the “powerhouses” of your cells. They generate ATP, the molecule that fuels everything from brain function to muscle movement. When mitochondria aren’t working properly, energy production drops—and you feel it as persistent fatigue.

Causes of mitochondrial dysfunction include:

Oxidative stress from poor diet, toxins, or chronic illness
Nutrient deficiencies in CoQ10, B vitamins, magnesium, and carnitine
Chronic infections or inflammation

Patients often describe mitochondrial fatigue as “bone-deep exhaustion” that doesn’t improve with rest. Supporting mitochondria with proper nutrition, lifestyle strategies, and sometimes regenerative therapies such as red light therapy with PEMF can restore energy at the cellular level.

2. Hormonal Imbalances

Hormones act like chemical messengers that regulate energy, metabolism, and mood. When they’re out of balance, fatigue is often the first sign.

Thyroid dysfunction slows metabolism, leading to sluggishness, weight gain, and brain fog.
Low testosterone or estrogen can reduce muscle mass, energy, and motivation.
Adrenal dysfunction (burnout from chronic stress) leaves patients feeling “wired but tired.”

We frequently see patients who were told their labs were “normal,” yet when we dig deeper with functional medicine testing, we uncover subtle imbalances that explain their fatigue.

3. Nutrient Deficiencies

Your body can’t make energy without the right raw materials. Deficiencies in certain vitamins and minerals are surprisingly common and often overlooked.

Iron deficiency reduces oxygen delivery to tissues, leaving you short of breath and exhausted.
Vitamin B12 and folate deficiencies impair red blood cell production and energy metabolism.
Magnesium is essential for ATP production and muscle relaxation.
Vitamin D deficiency not only affects bones but also energy, immunity, and mood.

At Sheen Vein & Cosmetics, we use advanced testing to pinpoint deficiencies. Replenishing nutrients often transforms how patients feel within weeks.

4. Gut Dysfunction and Dysbiosis

Your gut is often called your “second brain,” and for good reason. If your gut microbiome is out of balance, it can contribute to fatigue in several ways:

Poor absorption of nutrients needed for energy
Leaky gut, which promotes systemic inflammation
Overgrowth of harmful bacteria or yeast, producing toxins that drain energy
Immune activation, which diverts resources away from daily energy production

We see many patients whose fatigue improves dramatically once gut health is restored. Sometimes, addressing food sensitivities, infections, or dysbiosis is the missing piece of the puzzle.

👉 Learn more about how gut health impacts fatigue.

5. Chronic Infections and Inflammation

When your immune system is constantly “on,” it takes a toll on your energy. Chronic low-grade infections—such as Epstein-Barr virus, Lyme disease, or mold-related illness—can quietly drain the body for years.

The ongoing immune response leads to:

Mitochondrial damage
Hormonal disruption
Increased oxidative stress
Poor sleep and recovery

This creates a vicious cycle where inflammation worsens fatigue, and fatigue makes it harder to heal. Identifying and treating the underlying trigger is key to breaking this cycle.

A Functional Medicine Approach to Fatigue

The frustrating truth is that most patients with chronic fatigue don’t have just one cause—they have a combination of several. For example, mitochondrial dysfunction may coexist with thyroid imbalance and nutrient deficiencies. That’s why a one-size-fits-all solution rarely works.

At Sheen Vein & Cosmetics, we take a comprehensive approach by:

Running detailed lab testing to uncover hidden imbalances
Evaluating lifestyle factors such as stress, sleep, and nutrition
Creating a personalized plan that may include nutritional support, hormone optimization, gut repair, and regenerative therapies

Our goal isn’t just to help you feel less tired—it’s to restore your energy, focus, and quality of life.

Take the First Step Toward Restoring Your Energy

If you’ve been struggling with fatigue and haven’t found answers, you don’t have to accept exhaustion as your “new normal.” By identifying and addressing the root causes of chronic fatigue, you can reclaim your energy and vitality.

At Sheen Vein & Cosmetics in St. Louis, our team specializes in functional medicine and regenerative therapies designed to help you feel like yourself again.

👉 Learn more about our functional medicine services
👉 Schedule your consultation today

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