Fatigue

Symptoms

When should you discuss exhaustion or fatigue with a doctor?

If you have an infection or another diagnosed medical or psychological condition, some acute fatigue is to be expected. However, if you notice fatigue that is longer lasting or doesn’t have a clear physical/emotional cause, it’s probably wise to have a discussion with your healthcare provider.

All too often, clinicians see people with long-standing symptoms who could have benefitted from an earlier evaluation. Though fatigue doesn't always have an obvious cause, people tend to normalize it and delay discussing it.

Is there a duration of time or degree of fatigue that is medically concerning?  

Fatigue lasting more than a month inspires us to investigate further, especially if you don’t understand why it’s happening. Increased severity or new symptoms that all came about at the same time or feel connected to the tiredness also warrant discussion with a clinician.

Causes

What are some of the most common causes of fatigue?  

Lifestyle contributors include both lack of exercise and over-exercising, as well as poor diet/nutritional deficiencies,  inadequate sleep, chronic stress, and in some cases, chronic inflammation due to things like systemic metabolic problems or food intolerances.

Anxiety and depression are the most common mental health factors causing fatigue. One contributor in both conditions is sleep disruption, both in quantity and quality.  

In anxiety, your sympathetic nervous system (the fight-or-flight response) is more often triggered. That consistent release of adrenaline redirects energy to your brain at the expense of other body systems–and this shows up as exhaustion.  

Beyond sleep issues, the reason for fatigue in depression isn’t entirely clear. Some experts feel the increased energy it takes to function and accomplish tasks while depressed is the culprit.

The list of physical conditions that contribute to fatigue is extensive, but a few common ones are anemia, hypothyroidism, sleep apnea, diabetes, HIV, and mononucleosis. Side effects of medications make the list as well.

What are the most common nutritional deficiencies linked to fatigue and why do they make us tired?

Red blood cells carry oxygen throughout the body. A reduction in red blood cells or their capacity to function means less oxygen is distributed to body tissues–and this results in fatigue.

Vitamin B12 and B9 (folate) are necessary for red blood cell production, so low levels of either vitamin can lead to fatigue. Older people are particularly susceptible to low B12 levels due to gastric atrophy or pernicious anemia, an autoimmune condition that becomes more common with age.

Low iron is another common nutritional cause of fatigue. This can be caused by blood loss, reduced iron intake, or poor iron absorption. All of these things lead to low iron stores and eventually inadequate iron for the production of hemoglobin (the protein that carries oxygen within the red blood cells). Very low iron stores can cause fatigue even before anemia results.

Besides inadequate sleep, what other sleep problems cause fatigue?

Sleep apnea and insomnia are the most common culprits. Sleep apnea is an underdiagnosed condition that prevents normal restorative sleep due to interruptions in nocturnal breathing patterns.

Restless legs, narcolepsy, and circadian rhythm disorders can cause fatigue and all have unique symptomatology.

What’s the link between mononucleosis and fatigue?

Mononucleosis is usually caused by the Epstein Barr Virus and occasionally other viruses. One of the symptoms of infection with these viruses is severe fatigue.

Can age or gender help determine likely causes of fatigue?

Absolutely. Women are more likely to suffer from anemia (due to menstruation) and hypothyroidism, and they generally present with fatigue more often than men.  

Pregnancy-related fatigue is primarily due to hormonal changes in the first trimester. Third trimester fatigue is more often attributed to carrying extra weight and the sleep challenges that come with a changing body.

Advanced age increases risk for most causes of fatigue. Vitamin B12 deficiency, as mentioned above, is more common in older age. Chronic medical conditions–such as heart disease and medication use–also become more common as we age, leading to an increase in related fatigue.  

Stress and problems with sleep often fluctuate throughout one’s life, but these are probably more prevalent during stages where career and family life compete with personal health as priorities.

Diagnosis

Are there physical signs that point to certain causes of fatigue?

Thyroid problems can include a swollen neck, feeling unusually cold, unintentional weight gain, or a racing heart. Difficulty breathing or decreased exercise tolerance might point to anemia. We think about heart or liver problems if there is swelling in the abdomen or legs. A new heart murmur can point towards endocarditis (infection of a heart valve). Muscle weakness or other neurologic problems can be a sign of neurologic diseases. Swollen glands in someone with a history of cancer make us think about following up on their tumor.

What lab tests are most informative in a fatigue diagnostic work up?

A complete blood count (CBC) looks at white and red blood cells to rule out anemia and infection. Iron studies, B12 levels, and folate levels are the next things to measure when someone’s anemia is suspected to be due to a nutrient deficiency.  

Liver and kidney function, as well as electrolyte levels, help us evaluate those organs and look for signs of electrolyte imbalance.

Thyroid testing rules out thyroid dysfunction. HIV testing makes sense for those at risk and is recommended for all adults at least once in life. ESR or CRP, which are inflammatory markers, can be helpful to look at when we are concerned about specific inflammatory conditions.

A person with infectious symptoms, such as swollen glands and sore throat, may need testing for mononucleosis or other infections known to have prolonged recovery periods. If someone is behind on routine recommended screening (like colon cancer screening), that is useful as well.  

What is chronic fatigue?

Chronic fatigue is any fatigue lasting more than six months. Initially, medical and psychological reasons for fatigue should be evaluated and addressed, if present. If the fatigue persists despite that, and if it doesn’t fit the definition of Chronic Fatigue Syndrome (CFS), it is considered idiopathic fatigue–meaning the cause is unknown.

What about Chronic Fatigue Syndrome?

Chronic Fatigue Syndrome (also known as myalgic encephalomyelitis/CFS)  is a complex illness with specific diagnostic criteria and multiple possible causes. It is typically diagnosed in young-to-middle-aged adults, and in women more often than in men.

It usually presents as overwhelming fatigue (a kind that worsens with exertion), unrefreshing sleep, and other cognitive or physical symptoms. Diagnostic criteria are specific and the recommendations in the Treatment/Prevention section below do not apply to CFS.

Treatment & Prevention

What can you do if you think your fatigue is caused by depression, stress, or anxiety?

If fatigue coexists with one of these, it makes sense to address the depression, stress, or anxiety first and then track the fatigue as the mental health issue improves.

Astute clinicians will typically inquire about emotional health as a possible contributor to fatigue. If symptoms of depression are present, even though you may not meet all the diagnostic criteria for depression, treatment is recommended.

If no medical causes of fatigue are found, what can be done to help restore energy?

As a baseline, establish specific goals and meet regularly with a healthcare provider to review your progress.

Exercise is a great option that appears to have benefits for lessening fatigue. Start with light exercise that you can do at least 3x/week, increasing as tolerated. The improvement in energy is thought to be due to a direct effect on the central nervous system, independent of aerobic fitness.

Cognitive behavior therapy–which focuses on changing beliefs and behaviors that can affect symptoms and delay recovery–can be helpful as well. This does not mean that the fatigue is psychological, but rather that we can use CBT to optimize our psychological response and improve functioning.

Optimizing sleep can help, too. The specific approach will depend on the sleep challenge.

Eat a nutrient-dense diet high in fruits and vegetables, low in glycemic index, and low in sugar and caffeine to support your energy.  Adequate protein, but not too much, can help optimize your energy. It is digested slowly, which aids satiety and can reduce reliance on high carbohydrate foods as a short term energy source.  

Managing stress can be quite helpful, too. The optimal approach depends on the source of the stress, and resolving the primary stressor is the most successful approach. Short of that, journaling, meditation, and time in nature are just a few of the many options for stress relief.

A few herbs also show promise in mitigating the effects of stress leading to fatigue. Rhodiola rosea helps with attention, cognitive function, and mental performance. Schizandra chinesis and Eleutherococcus senticoscus support increased endurance and mental performance. Overarchingly, these adaptogenic herbs work to protect against stress through regulating molecular mediators of the stress response. They provide another tool to optimize our adaptation to stress, which should result in improvement in fatigue.

Useful Links

Diagnostic Criteria for CFS (Institute of Medicine)

Polysomnography in fatigue (Choosing Wisely)

Prevalence of fatigue and chronic fatigue syndrome (Archives of Internal Medicine)

Exercise as a cure for exhaustion (NY Times)

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