What Is Fatigue?

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What Is Fatigue?

Fatigue

Fatigue is ongoing exhaustion that can be both physical and mental, creating limitations in cognitive, social, emotional, and physiological functioning.

Adjectives such as tired, restless, drowsy, and exhausted are often used to describe fatigue. It is usually a result of lack of sleep or stress. Although fatigue is not a medical condition itself, it can be a symptom of a disease if it is chronic or the condition identified as Chronic Fatigue Syndrome (CFS).  

Fatigue is considered peripheral when it impacts the muscles, causing pain, soreness, and weakness. It is defined as central fatigue when it causes cognitive and psychological impairments. A person may experience either central or peripheral fatigue, but it is just as possible to be burdened by both. 

Fatigue dramatically impacts quality of life (QoL), affecting productivity and the ability to complete tasks, limiting functioning.

Between 30% and 50% of the population experiences fatigue. Although fatigue has a significant impact on many lives, healthcare professionals do not entirely understand fatigue and how to treat it. 

Types of Fatigue

The concept of fatigue is vague; it can occur in different forms and persist for various time lengths. Types of fatigue are somewhat tricky to decipher because symptoms are often the same, with differentiation in the duration and onset of the fatigue. Below you will find variations of fatigue.

Acute Fatigue

Acute fatigue is fatigue that usually resolves after rest and often occurs due to lack of sleep, stress, burnout, or overexertion of the muscles. It must only persist for one month or less for fatigue to be considered acute.

Prolonged Fatigue

This continuous fatigue persists for 1 to 6 months. This fatigue is not necessarily due to a chronic condition but possibly lifestyle habits or environmental stressors. Prolonged fatigue occurs for 1 to 6 months.

Chronic Fatigue

Chronic fatigue is fatigue that exists for six months or longer. It is usually a symptom of a chronic condition and is not relieved by rest.

Chronic Fatigue Syndrome (CFS)

CFS is a condition whose cause is unidentified. An individual is usually diagnosed with CFS when there is no other explanation for the occurrence of chronic fatigue.

Work-Related Fatigue

This fatigue is associated with stress due to work demands, called "burnout." Burnout is due to being overworked and not having enough leisure time or rest.

Causes

There are many possible causes of fatigue:

Fatigue's Impact On Chronic illnesses

Between 40% and 74% percent of patients with chronic diseases suffer from fatigue. Although all chronic diseases consist of different variations of symptoms and limitations, the experience of fatigue is usually similar across illnesses. Many patients reported fatigue as one of the most disabling aspects of their disease. 

Even though it is true that many individuals with chronic illnesses are affected by peripheral fatigue, however, central fatigue most commonly abides in every chronic disease. Central fatigue implies abnormalities in neurotransmitters within the central nervous system.In addition, it plays a significant role in chronic inflammatory conditions.

Inflammation is associated with almost every ailment; this includes cancers, autoimmune diseases like multiple sclerosis (MS), inflammatory bowel diseases (IBD), arthritis, fibromyalgia, irritable bowel syndrome (IBS), psychiatric disorder, and CFS.

Chronic inflammatory conditions are associated with large amounts of inflammation within the body. Inflammation is suspected to be a possible link to fatigue and mood disorders such as depression because they both present high inflammatory markers and often coexist.

When examining fatigue across five different chronic illnesses (heart failure, multiple sclerosis, rheumatoid arthritis, chronic kidney disease, and chronic obstructive pulmonary disease), researchers "found that fatigue was characterized by severe energy depletion."

When patients expressed their experiences with fatigue, "four common themes emerged: running out of batteries, a bad life, associated symptoms (e.g., sleep disturbance, impaired cognition, and depression), and feeling misunderstood by others, with a fear of not being believed or being perceived negatively."

Lifestyle Changes Can Help Those With Chronic Illnesses

For those with chronic illnesses, lifestyle interventions, like physical activity and healthy sleep hygiene can help with fatigue symptoms.

Pharmaceuticals prescribed for the condition may help with fatigue by treating the symptoms of the disease. However, It is also possible for the medication to cause fatigue.

When patients complain of fatigue, it is often disregarded. Although it significantly impacts an individual's daily functioning, physicians' ultimate goal is to treat the illness itself, causing fatigue to fade into the background.

Chronic fatigue is "misunderstood and inadequately acknowledged" by outside parties. It can be difficult for others to recognize the anguish that chronic fatigue is causing someone.

Comorbidity

Fatigue can be difficult to fully understand because it often coexists with many other intrusive symptoms, such as the following:

How to Manage Fatigue

Fatigue is the most common complaint reported to primary care physicians (PCP), but there is currently no straightforward treatment method.

Since fatigue doesn't necessarily appear to be a health risk, physicians do not often focus a great deal on these complaints once they rule out any major threats. Fatigue does, however, severely plummet quality of life, and many individuals are on the prowl for answers regarding this symptom.

Below you will find ways to manage fatigue.

Eat a Nutritious Diet

A well-balanced diet indeed contributes to energy levels. Over-consumption of unnutritious foods and not receiving an adequate amount of foods that offer nutritional value can trigger fatigue, especially for those with inflammatory conditions. 

Anti-inflammatory diets, which is a diet that consists of whole grains, omega fatty acids, and vegetables, were found to be beneficial for individuals with chronic illnesses and symptoms of fatigue. 

"Clinical studies demonstrate that a balanced diet with whole grains high in fibers, polyphenol-rich vegetables, and omega-3 fatty acid-rich foods might improve disease-related fatigue symptoms."

Practice Good Sleep Hygiene

Sleep helps revitalize the body and maintain its functioning. When sleep is disturbed, the body is affected in many ways, and fatigue is the most common sign that the body needs rest. 

A research study exploring the relationship between fatigue and quality of sleep in healthy postpartum women found less sleep to be associated with "higher levels of fatigue." In addition, the women who reported poor sleep quality or insufficient amounts of sleep were more fatigued.

Try Complementary Alternative Medicine (CAM)

Complementary alternative medicine (CAM) (e.g., meditation, yoga, acupuncture, massages, etc.) can aid in managing fatigue symptoms. 

Researchers sent a survey to 2,728 households in the United States. Of the 884 who completed the survey, 440 reported experiences of fatigue. A large amount of those individuals partook in CAM therapies, and prayer was the most popular.

Participants with fatigue indulged in mindfulness and relaxation techniques more often than the general population. More than any other group, individuals with chronic fatigue due to an illness mainly engaged in massages and chiropractic work, most likely because of physical fatigue and muscle pain. 

Make Time for Leisure

Not having enough relaxation and leisure time can cause burnout or stress-related fatigue. Researchers found stress-related fatigue to be associated with factors like work demands, "little vacations or leisure time," and working overtime.

It is essential to have a little downtime because stress can often lead to fatigue. Hobbies are excellent activities to engage in during downtime, like taking walks or reading a book. 

Get Exercise

A regular physical activity regimen is vital for maintaining health and can help with reducing fatigue. The World Health Organization (WHO) suggests adults engage in 75 to 150 minutes of physical activity throughout the week.

A meta-analysis reviewing the impact that physical activity had on fatigue symptoms in MS patients determined that physical activity significantly reduced fatigue.

Research also shows that physical activity positively influences sleep quality, decreasing fatigue due to better sleep.

Connect With Your Spirituality

Spiritual well-being can play a role in the management of fatigue symptoms as well. Researchers studying the influence that spiritual well-being and hope had on the fatigue of cancer patients undergoing chemotherapy, discovered an individual’s spiritual well-being contributed to their experience with fatigue greatly. 

"Participants with higher fatigue had lower scores for hope and lower scores for spiritual well-being.” Researchers believe that spiritual well-being may act as a mediator for hope and fatigue. Their theory is that spiritual-well being can increase hope, and hope can then help reduce fatigue symptoms.

A Word From Verywell

If you've been feeling fatigued for an extended amount of time, it might be due to a mental health or physical issue. See your healthcare provider so they can help you figure out what might be causing your fatigue.

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17 Sources
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  1. Lewis G, Wessely S. The epidemiology of fatigue: more questions than answers. J Epidemiol Community Health. 1992;46(2):92-97. doi:10.1136/jech.46.2.92

  2. Swain MG. Fatigue in chronic disease. Clin Sci (Lond). 2000;99(1):1-8.

  3. Son CG. Differential diagnosis between "chronic fatigue" and "chronic fatigue syndrome". Integr Med Res. 2019;8(2):89-91. doi:10.1016/j.imr.2019.04.005

  4. Rose DM, Seidler A, Nübling M, et al. Associations of fatigue to work-related stress, mental and physical health in an employed community sample. BMC Psychiatry. 2017;17(1):167. Published 2017 May 5. doi:10.1186/s12888-017-1237-y

  5. Rychnovsky J, Hunter LP. The relationship between sleep characteristics and fatigue in healthy postpartum women. Womens Health Issues. 2009;19(1):38-44. doi:10.1016/j.whi.2008.07.015

  6. Christie AD, Seery E, Kent JA. Physical activity, sleep quality, and self-reported fatigue across the adult lifespan. Exp Gerontol. 2016;77:7-11. doi:10.1016/j.exger.2016.02.00

  7. Black, C.D., O'Connor, P.J. & McCully, K.K. Increased daily physical activity and fatigue symptoms in chronic fatigue syndrome. Dyn Med 2005;4(3). doi:10.1186/1476-5918-4-3

  8. Louati K, Berenbaum F. Fatigue in chronic inflammation - a link to pain pathways. Arthritis Res Ther. 2015;17:254. Published 2015 Oct 5. doi:10.1186/s13075-015-0784-1

  9. Menting J, Tack CJ, Bleijenberg G, et al. Is fatigue a disease-specific or generic symptom in chronic medical conditions?. Health Psychol. 2018;37(6):530-543. doi:10.1037/hea0000598

  10. Jaime-Lara RB, Koons BC, Matura LA, Hodgson NA, Riegel B. A Qualitative Metasynthesis of the Experience of Fatigue Across Five Chronic Conditions. J Pain Symptom Manage. 2020;59(6):1320-1343. doi:10.1016/j.jpainsymman.2019.12.358

  11. Zielinski MR, Systrom DM, Rose NR. Fatigue, Sleep, and Autoimmune and Related Disorders. Front Immunol. 2019;10:1827. Published 2019 Aug 6. doi:10.3389/fimmu.2019.01827

  12. Torres-Harding S, Jason LA. What Is Fatigue? History and Epidemiology. In J. DeLuca (Ed.), Fatigue as a window to the brain. MIT Press. 2005. 3-11. 

  13. Haß U, Herpich C, Norman K. Anti-Inflammatory Diets and Fatigue. Nutrients. 2019;11(10):2315. Published 2019 Sep 30. doi:10.3390/nu11102315

  14. Jones JF, Maloney EM, Boneva RS, Jones AB, Reeves WC. Complementary and alternative medical therapy utilization by people with chronic fatiguing illnesses in the United States. BMC Complement Altern Med. 2007;7:12. Published 2007 Apr 25. doi:10.1186/1472-6882-7-12

  15. Piercy KL, Troiano RP, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320(19):2020–2028. doi:10.1001/jama.2018.14854

  16. Razazian N, Kazeminia M, Moayedi H, et al. The impact of physical exercise on the fatigue symptoms in patients with multiple sclerosis: a systematic review and meta-analysis. BMC Neurol. 2020;20(1):93. Published 2020 Mar 13. doi:10.1186/s12883-020-01654-y

  17. Jun SY, Ko IS. Cancer patients receiving chemotherapy, the spiritual well-being, hope the impact of fatigue. Korean J Adult Nurs. 2012;24(6):557–568. doi:10.7475/kjan.2012.24.6.557