How Common Is Fatigue - Energy And Fatigue: Chronic Fatigue

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How common is fatigue?

One of the significant challenges facing contemporary scientists studying fatigue is how to measure its prevalence. Unlike diabetes, obesity, or other well-defined medical conditions, fatigue is very difficult to define because it has varied symptoms and, like pain, is both an objective and subjective state. Moreover, fatigue is part of the human experience and is, at times, entirely normal. In the absence of a clear-cut definition or objective "fatigue test," measuring how many people experience fatigue — and when it crosses the line from normal to abnormal — is imprecise at best. Despite these hurdles, researchers who have looked at the results of numerous epidemiological (population-based) studies of fatigue have been able to draw some conclusions about its prevalence.

The first is that fatigue is very common. In a comprehensive epidemiological health survey of more than 9,000 adults in Britain, for example, only headaches were more common than fatigue, which affected approximately 25% of respondents. A U.S. study reached similar conclusions, with 24% of those polled reporting excessive fatigue. While the statistics vary somewhat because of differences in how fatigue is defined, studies done in France, Algeria, Germany, Taiwan, Iceland, Mexico, and elsewhere lead to the same basic conclusion: Fatigue is one of the most common symptoms — and in some studies, the most common symptom — experienced by people in the general population.

Perhaps not surprisingly, fatigue is also one of the leading reasons people around the world visit primary care providers. One U.S. survey concluded that fatigue was responsible for more visits to primary care doctors than colds, rashes, headaches, or chest pains.

Numerous studies indicate that people who see their doctor about fatigue have generally experienced it for a considerable length of time — anywhere from six months to several years. In addition to being chronic, fatigue can be disabling. In one English study, for example, 26% of primary care patients who suffered from fatigue said it forced them to limit their usual activities. Another study found that people with chronic diseases such as diabetes and arthritis function better than people who are chronically fatigued.

The great majority of epidemiological studies conclude that fatigue is more common in women than in men. In the British study mentioned earlier, 30% of women said they were fatigued, compared with 19% of men. There are many theories as to why this might be so — from women's role in society and the biological differences between women and men, to the higher incidence among women of depression, which is associated with fatigue.

Studies conducted in various countries, including the United States, Britain, Australia, and France, have found that people in lower social classes are more fatigued than those of a higher social standing. For example, in the large British health survey, 22.5% of employers and managers reported "always feeling tired" during the previous month, compared with nearly 28% of semiskilled and unskilled manual workers. Low socioeconomic status is linked to unemployment and other adverse conditions, which might contribute to fatigue.

Studies have found that age, however, is not a factor in fatigue, with the exception of adolescence, when it is uncommon. Whether fatigue is more prevalent in old age is controversial; some studies say yes, while others say no. One complicating issue is the role of physical illness as a cause of fatigue among older adults.

Although fatigue is difficult to define and a challenge to measure, this much is clear: If you sometimes feel fatigued, you are certainly not alone. Fortunately your body is geared toward generating energy as well as expending it.

Last updated:	January 23, 2007