What is fatigue?

Fatigue refers to an overwhelming sense of tiredness, lack of energy, and feeling of exhaustion. It can have both physical and mental components.

When does fatigue become abnormal? Persistent feelings of extreme fatigue that are not relieved by rest may indicate an underlying medical issue. If fatigue interferes with daily life over an extended period of time, it's a good idea to talk to your doctor.

There are a lot of potential causes behind abnormal and chronic fatigue syndromes, including:

Now to dig deeper into the physiology behind fatigue... What actually happens inside the body when we feel tired?

In simple terms, fatigue sets in when our cells run low in energy. The main cellular fuel source is ATP (adenosine triphosphate). ATP provides energy to power muscle contraction, nerve impulses, chemical reactions, and other vital cell activities.

ATP is continuously regenerated in cellular energy factories called mitochondria. Here, nutrients from food are converted to ATP through processes like:

Therefore, inadequate nutrient intake, mitochondrial dysfunction, or inborn errors of metabolism can all potentially disrupt ATP regeneration --> triggering feelings of exhaustion and muscle weakness.

"I'm so tired my mitochondria must be on strike!"

Other contributing factors to fatigue include:

As you can see, fatigue is complex with a wide array of potential interplaying causes. Getting to the root issue(s) requires a systematic, multi-modal analysis - blood tests, genetic testing, sleep studies, toxicity screens, hormone panels, and so forth.

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