Woman surrounded by cups of coffee with her head on her deskFatigue is a state of feeling extremely tired, exhausted, and weak. It differs from chronic fatigue syndrome (CFS), which is its own condition. Fatigue can be experienced physically, mentally, or as a combination of both. When someone is fatigued, they may not be able to function at their best. Working with a therapist helps many individuals discover and treat the cause of their fatigue.

What Is Fatigue?

While everybody feels tired from time to time, persistent and constant fatigue can become problematic. Extreme fatigue can be dangerous, because a decreased level of alertness could impair an individual’s ability to drive a car or operate heavy machinery. In some cases, fatigue can be extreme but short lived; this is most often the case when the cause of fatigue is immediate, such as when fatigue is due to a lack of sleep the night before. When fatigue lasts for months with no apparent cause, it becomes chronic fatigue. 

Individuals who experience chronic fatigue may have difficulty engaging in strenuous physical tasks or have muscle weakness and less physical strength than they are accustomed to. Chronic fatigue can also make it difficult for people to complete simple daily tasks or concentrate. As a result, they may find it harder to get through the day or that their productivity at work or in school decreases. Preparing meals, maintaining personal hygiene, and healthy social engagement may start to feel like too much work.

Fatigue Causes

There are many different physical and psychological causes of fatigue. Some common fatigue triggers include:

  • Underlying medical conditions such as kidney disease, diabetes, hypothyroidism or hormonal imbalance, anemia, heart disease, problems with the immune system, or pneumonia
  • Infections, including viral infections such as influenza or mononucleosis
  • Vitamin deficiency
  • Sleep disorders such as insomnia or sleep apnea
  • Pregnancy 
  • Chronic pain
  • Chronic fatigue syndrome
  • Mental health issues including stress, depression, or anxiety

Medications and treatments can also cause fatigue. For example, people who undergo chemotherapy treatment for cancer may experience chronic fatigue for years after the treatment has ended. Medications such as statins, antihistamines, and sedatives are also known to cause fatigue.

Chronic Fatigue Syndrome (CFS)

People may become confused by the many terms used to describe different types of fatigue. For instance, chronic fatigue is different from chronic fatigue syndrome, although the latter may also be referred to as chronic fatigue.

CFS is a medical condition also known as myalgic encephalomyelitis. It’s characterized by intense and persistent exhaustion and is often diagnosed when three main symptoms are present:

  1. Chronic fatigue that impacts daily life and activity levels and which has lasted more than 6 months.
  2. Activities that did not previously cause fatigue now make symptoms of CFS worse.
  3. Persistent sleep problems, including insomnia or feeling tired even after a full night of sleep.

CFS may be accompanied by loss of memory or impaired concentration, sore throat, enlarged lymph nodes, muscle pain, headaches, non-restful sleep, and joint pain. Chronic pain and trouble sitting upright may also affect those with chronic fatigue syndrome.

Fatigue and Mental Health

Both fatigue and chronic fatigue syndrome may be tied to mental illness. Some mental health conditions that may either cause or turn up as symptoms of fatigue include:

  • Addictions or substance abuse: Fatigue can be a symptom during the withdrawal process of many substances, including caffeine, alcohol, and opioids. 
  • Grief: Grief has been known to affect the body physically, often increasing a person’s risk for health problems. Symptoms of grief may mimic those of depression, and a common product of grief is fatigue. 
  • Depression: Depression and fatigue often co-occur, and fatigue can be a common symptom of depression. 
  • Anxiety: Fatigue caused by lack of sleep has been shown to worsen symptoms of anxiety, and anxiety may cause tiredness due to insomnia or fatigue from remaining in fight or flight mode.
  • Eating disorders: Obsessive thoughts related to food that accompany many eating disorders may cause fatigue. Unhealthy eating habits brought on by eating disorders, such as binging, purging, or starvation can also physically weaken the body or lead to weight loss or gain, causing fatigue.
  • Burnout: Having a high-stress or demanding career such as being a surgeon, pilot, or athlete may lead to burnout, which comes hand-in-hand with fatigue.
  • Stress: Situations that cause psychological stress such as moving, divorce, and becoming a new parent are also known to cause fatigue.  

The relationship between mental health conditions and fatigue is not always clear. In some cases, fatigue may subside when the mental health symptoms are treated, but in other cases, fatigue may be a separate issue that persists even when the mental health issue has been adequately addressed. Because CFS and depression share some common traits, doctors may misdiagnose chronic fatigue syndrome as depression. 

Just as mental health issues cause fatigue, so may chronic fatigue contribute to mental health symptoms. For example, people who often experience fatigue may have difficulty participating in activities that make them feel happy and fulfilled, which could lead to depression. In this way, fatigue and depression can become a cycle that may be difficult to disrupt. 

Dealing with any kind of fatigue on a regular basis can be frustrating, especially if it is particularly resistant to your treatment efforts. Working with a therapist can help people cope with the mental health effects of fatigue or CFS and learn new strategies for managing it.


  1. Chronic fatigue syndrome. (2017, October 5). Mayo Clinic. Retrieved from http://www.mayoclinic.org/diseases-conditions/chronic-fatigue-syndrome/basics/definition/con-20022009
  2. Myalgic encephalomyelitis/chronic fatigue syndrome: Symptoms. (2018, May 18). Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/me-cfs/symptoms-diagnosis/symptoms.html 
  3. Nall, R. (2017, July 5). Fatigue and depression: Are they connected? Retrieved from http://www.healthline.com/health/depression/fatigue#Overview1
  4. Nordqvist, C. (2017, August 15). Fatigue: Why am I so tired and what can I do about it? Retrieved from http://www.medicalnewstoday.com/articles/248002.php
  5. Romm, C. (2014, September 11). Understanding how grief weakens the body. Retrieved from https://www.theatlantic.com/health/archive/2014/09/understanding-how-grief-weakens-the-body/380006 
  6. Sleep and mental health: Sleep deprivation can affect your mental health. (2018, June 19). Harvard Health Publishing. Retrieved from https://www.health.harvard.edu/newsletter_article/sleep-and-mental-health 
  7. Study finds greater activation of biological fight or flight mechanism in chronic fatigue syndrome patients. (2016, May 18). Retrieved from https://www.news-medical.net/news/20160518/Study-finds-greater-activation-of-biological-fight-or-flight-mechanism-in-chronic-fatigue-syndrome-patients.aspx 
  8. The sleep effect: Combating fatigue during alcohol addiction treatment. (n.d.). Retrieved from https://www.clearviewtreatment.com/sleep-effect-combating-fatigue-alcohol-addiction-treatment.html 
  9. Williamson, R. J., Purcell, S. Sterne, A., Wessely, S., Hotopf, M., Farmer, A., & Sham, P. C. (2005). The relationship of fatigue to mental and physical health in a community sample. Social Psychiatry & Psychiatric Epidemiology, 40(2), p. 126-132. doi: 10.1007/s00127-005-0858-5