4 June 2020

What is fatigue?

Fatigue is extremely difficult to measure, and by extension manage. Read on to hear about classic definitions of fatigue, related areas of scientific interest, how it is measured, and how Cambridge Cognition plans to explore the issue.

What is fatigue?

Fatigue refers to whole-body exhaustion not proportional to recent activity, and often accompanied by decreased strength, weariness, sleepiness, and irritability, and cognitive problems [1,2]. These experiences often interfere with daily activities and social activities, and contribute to distress and low quality of life [3].

Persistent fatigue is recognised as an important, but subjective and clinically non-specific part of living with chronic long-term illness [4]. Fatigue is associated with many chronic diseases, including but not limited to multiple sclerosis, heart failure, liver disease, systemic lupus, cancer, rheumatoid arthritis and depression [5]. Qualitative research suggests that fatigue is overwhelming, but hard to describe [2]. This, along with its subjective nature and non-specificity may make it particularly challenging to assess and treat.

Who is researching fatigue?

In patients with chronic health conditions, fatigue is often rated as one of the most challenging and problematic aspects of their disease [6]. There has been a steep increase in scientific interest in the scientific and clinical community in the last four decades (figure 1). Scientific endeavour examines a range of affected conditions and associated problems, and uses a range of different types of research approaches to examine to fatigue (figure 2).

Figure 1: yearly number of records with the word ‘fatigue’ in the title, identified through Pubmed. PubMed is a free search engine accessing references and abstracts in the live sciences and biomedical research maintained by the US National Library of Medicine and the National Institutes of Health (

Figure 2: Word cloud of most frequent terms included in titles of research records which include ‘fatigue’ over the last 5 years from Pubmed search (2015-2020). CFS/ME = Chronic Fatigue Syndrome/myalgic encephalomyelitis

How do we measure fatigue?

There a range of different questionnaires to assess fatigue, and many have been developed to be used only in specific diseases [7]. These questionnaires often tap into various facets of fatigue, including for example, sensory, mood, cognitive, motivation, physical, and activity related impairments [5]. However, if fatigue differs from one patient population to another, measures developed for one patient group may not be as informative in another [7].

Research report: How do patients experience their fatigue?

Interested in how patients with long-term health conditions and severe fatigue experience and manage their fatigue, as well as their experiences with treatments, Cambridge Cognition recently completed a small-scale feasibility study. The study included a written survey and used open-ended questions. These asked about:

how patients with chronic health conditions experienced fatigue
what the most significant symptoms of fatigue were
how patients managed their fatigue
how patients selected treatments and therapies
downsides to treatments and difficulties accessing treatments
The results of the study are freely available on our eBook.

Who can I speak to?

If you have any questions about our research, please do get in touch:

If you are a person living with fatigue, and are looking for advice and support in managing your condition, we would encourage you to speak with your GP. You can also obtain more information from these charities:

If you live in the UK, you can also find Chronic Fatigue Syndrome services in your area here.


1. Louati K, Berenbaum F. Fatigue in chronic inflammation – a link to pain pathways. Arthritis Res Ther [Internet] Arthritis Research & Therapy; 2015;17(1):1–10. PMID:26435495

2. Whitehead LC, Unahi K, Burrell B, Crowe MT. The Experience of Fatigue Across Long-Term Conditions: A Qualitative Meta-Synthesis. J Pain Symptom Manage [Internet] Elsevier Inc; 2016;52(1):131-143.e1. [doi: 10.1016/j.jpainsymman.2016.02.013]

3. Bootsma TI, Schellekens MPJ, Woezik RAM, Lee ML, Slatman J. Experiencing and responding to chronic cancer‐related fatigue: A meta‐ethnography of qualitative research. Psychooncology 2019;(August):1–10. [doi: 10.1002/pon.5213]

4. Wilson L, Whitehead L, Burrell B. Learning to live well with chronic fatigue: The personal perspective. J Adv Nurs 2011;67(10):2161–2169. [doi: 10.1111/j.1365-2648.2011.05666.x]

5. Hjollund NH, Andersen JH, Bech P. Assessment of fatigue in chronic disease: A bibliographic study of fatigue measurement scales. Health Qual Life Outcomes 2007;5:1–5. [doi: 10.1186/1477-7525-5-12]

6. Swain MG. Fatigue in chronic disease. Clin Sci 2000;99(1):1–8. [doi: 10.1042/cs0990001]

7. Dittner AJ, Wessely SC, Brown RG. The assessment of fatigue: A practical guide for clinicians and researchers. J Psychosom Res 2004;56(2):157–170. [doi: 10.1016/S0022-3999(03)00371-4]

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Dr Caroline Skirrow

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