What are the most common causes of chronic fatigue?

Sleep apnea, thyroid problems, B12 or iron deficiency, and depression are among the most common and well-established causes, though a proper evaluation with bloodwork is needed to identify the specific cause in your case.

Could my fatigue be a sleep apnea?

Possibly, especially if you snore, gasp, or have been told you stop breathing at night — a sleep study, which your doctor can order, is the definitive way to check.

Is adrenal fatigue a real medical diagnosis?

Adrenal fatigue is a popular but not well-supported diagnosis in mainstream medicine — the underlying symptoms are real, but they usually trace back to more established causes like thyroid issues, sleep problems, or nutrient deficiencies.

The #1 reason Americans see a doctor →

Find the likely root cause of your fatigue.

Persistent fatigue can stem from many different causes — sleep, thyroid, nutrient deficiencies, or mood. Answer a few questions to identify the most likely explanations and appropriate next steps.

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Everything about fatigue, organized properly

From finding your likely cause to understanding thyroid, sleep, and nutrient-related fatigue.

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Find Your Cause

A root-cause analysis of your fatigue.

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Thyroid & Fatigue

An often-overlooked connection.

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Sleep Apnea

A common, underdiagnosed cause.

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B12 & Iron Deficiency

Nutrient gaps that cause fatigue.

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Fatigue and Mood

The depression connection.

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Adrenal Fatigue Debate

What the evidence actually says.

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Fatigue Root Cause Analyzer

Answer a few questions about your fatigue pattern, sleep, and lifestyle to identify likely causes worth exploring.

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The essentials

Fatigue is the #1 reason Americans see a doctor — and it has many possible causes

Fatigue tops the list of reasons Americans visit their doctor, yet it's also one of the most nonspecific symptoms, with causes ranging from sleep apnea to thyroid issues to simple nutrient deficiencies.

The pattern of your fatigue is informative

Morning fatigue, afternoon crashes, and constant low energy each point toward somewhat different likely explanations.

Sleep quality is often the overlooked piece

Sleep apnea in particular is commonly missed, since people experiencing it often aren't aware their sleep is being interrupted.

Fatigue and mood are deeply connected

Depression frequently presents with fatigue as a primary symptom, sometimes before mood changes become obvious.

Key takeaway

Fatigue's many possible causes — thyroid, sleep apnea, nutrient deficiencies, and mood — mean that paying attention to the specific pattern of your fatigue helps identify the most useful next step to explore with your doctor.

Helpful next steps

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🩺Get a telehealth consultationDiscuss bloodwork options for your fatigue 🛡️Explore energy-supporting supplementsB12, iron, and magnesium options

This content is for general educational purposes only and is not a substitute for personalized medical advice. Bloodwork ordered by your doctor is the only way to confirm the underlying cause of fatigue.

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The Chronic Fatigue Root Cause Guide

A free PDF covering the most common causes of fatigue — thyroid, sleep apnea, nutrient deficiencies, and mood — and what to explore with your doctor.

8+ common causes of chronic fatigue
How thyroid issues can cause fatigue
Recognizing sleep apnea as a hidden cause
B12 and iron deficiency, explained
The adrenal fatigue debate, honestly covered