With more people suffering from fatigue than ever before, there’s still not a universally accepted definition, let alone a thorough medical understanding of fatigue. Even worse, there’s still no standard practice of treating it.  Information on the topic is so conflicting that if you asked a dozen doctors, “What is fatigue?” you more than likely would receive a dozen different answers!

Defining fatigue

Fatigue can be defined as an overwhelming sustained sense of exhaustion and decreased capacity for physical and mental work at the usual level. It typically follows a period of mental or physical activity. Once fatigue sets in, your ability or motivation for work goes caput, your ambition plummets, and you may feel weary, sleepy, tired, exhausted, depressed, spacey, weak, or irritable.

When fatigue becomes chronic, your physical and mental health is in jeopardy.  You may know first-hand what it feels like to experience relentless, day-after-day fatigue. Over time, fatigue takes its toll on every aspect of your body and mind, zapping your health and your ability to cope with life, interfering at home, at work, and in your relationships.

In some ways, the answer to “What is fatigue?”  is fairly straightforward: fatigue is a lack of energy, and the generation of energy is a fairly well-understood biochemical process. The little energy factories in your cells, called mitochondria, burn the food you eat in the presence of oxygen to produce energy.  So, when the mitochondria are not working properly, the resultant loss of energy shows up as fatigue.

A complex condition

In reality, fatigue is much more complex and multidimensional. It is related not simply to improper functioning of the mitochondria, but with many other body systems, biochemical reactions, and psychological, environmental, and lifestyle factors.

It’s no surprise that practitioners of natural and integrative medicine tend to be more adept at recognizing these complex interrelationships among many diverse variables when it comes to fatigue.  And they recognize, as fatigue researchers are now starting to validate, that fatigue results from a complex set of interacting factors rather than a single cause.  In other words, everything that has ever happened to you collectively brings you to the place of feeling fatigued.

Some of these interrelated fatigue variables include:

• Hormone imbalances such as thyroid, testosterone, estrogen, and progesterone
• Hypothalamic Pituitary Adrenal axis (HPA-axis) dysfunction such as low cortisol and DHEA
• Stress and mood disorders such as depression and anxiety
• Poor sleep and sleep disorders such as sleep apnea and insomnia
• Nutrition and digestive issues such as nutritional deficiencies, excessive gut permeability, food allergies, and blood sugar dysregulation
• Sedentary lifestyle and deconditioning
• Chronic infections such as Lyme, hepatitis, Candida, Epstein Barr
• Mitochondrial damage or dysfunction
• Poor detoxification mechanisms or excessive toxic exposures such as heavy metal toxicity

So, while the answer to “What is fatigue?” may be complex, the good news is that there are natural solutions you can implement yourself to address every one of these fatigue-related underlying causes. Discovering the root cause of your fatigue will be your initial step to recovery.

This post originally appeared in 2013 and has been updated.