There are many reasons that could underlie extreme fatigue in women. Web MD lists some 7 factors that are the most common reasons for fatigue in women. Fatigue could be caused by anemia which causes hemoglobin deficiency and hence lack of energy.
Additionally hypothyroidism (underactive thyroid), an undiagnosed urinary tract infection, an overdose of caffeine, certain food intolerances, sleep apnea and an undiagnosed disease of the heart could be underlying causes of fatigue experienced by women.
Though these are the common causes, extreme fatigue in women could have these or other underlying causes as well –
Depression, anxiety, stress, lack of sleep – For women, who typically have to juggle home and professional commitments as well, stress is a reality of life – simply taking on too much to do can be a cause of fatigue.
Research has shown that women are particularly prone to anxiety and depression (twice as many women have depression as do men) and these can generate extreme fatigue in women.
Accompanying the fatigue could be other symptoms such as feelings of hopelessness or guilt, a greater desire to sleep, an unexplained weight gain, difficulty concentrating and so on.
Sometimes the fatigue could be caused by something as simple as lack of restful sleep, 
since insomnia and fatigue are closely linked. Indicators could be nodding off at inopportune times, being surprised by yawns when least expected, and general lethargy.
Certain underlying infection could cause extreme fatigue in women
While the actual cause-effect relationship between certain infections and extreme fatigue may be the subject matter of debate, it is true that there seems to be some connection between the two.
In some cases, the virus that causes pneumonia is known to be connected to extreme fatigue. Also, digestive problems such as constipation or diarrhea may cause fatigue.
It is possible that diarrhea leads to feelings of tiredness and fatigue due to the resultant dehydration and depletion of salts and vital nutrients from the body. Infections such as bronchitis that affect the lungs are also seen to cause extreme fatigue.
Some experts also believe that extreme fatigue in women could be caused by a liver problem called Hematochromatosis which may also have symptoms such as a grayish cast to the skin, and arthritis.
Lyme disease, an infection caused by ticks, is also implicated as being a cause for fatigue. This infection would also cause a typical kind of skin rash, muscle and joint pain, fever and so on.
Extreme fatigue among women is one of the main symptoms of certain conditions such as fibromyalgia, which is characterized by extreme but unexpected body pain as well.
Eating disorders could cause extreme fatigue in women
Anorexia, bulimia and similar eating disorders could mean that an insufficient amount of calories are being obtained for proper functioning. The lack of nutrients would mean feeling tired and drained of energy.
Also engaging in other harmful behaviors such as purging by taking diuretics or laxatives to lose weight can mean extreme fatigue. Rather like diarrhea, these can deplete the system of certain vital nutrients and salts so that the body is drained of energy and feels tired.
More resources:
Pros And Cons Of Taking Iron Supplements For Anemia
Are You Aware Of These Common Problems Which Are Stealing Your Sleep?
