Chronic fatigue can occur with a wide variety of disorders, ranging from cancer to sleep deprivation. Fatigue serves as a general warning signal, indicating a problem somewhere in the body. Common chronic diseases prove the most frequent causes of chronic fatigue. Examples include heart failure, chronic lung disease, anemia and sleep apnea.
Anemia
A deficiency in the number of circulating red blood cells or insufficient hemoglobin in the red blood cells characterizes the condition of anemia. Red blood cells carry oxygen to the body tissues; hemoglobin serves as the oxygen carrier within the red blood cells. Anemia decreases the oxygen level in the tissues, hampering optimal cell function and provoking fatigue. The National Heart, Lung and Blood Institute explains that anemia occurs due to inadequate production of red blood cells, premature destruction of red blood cells or blood loss. Acquired forms of anemia, such as iron deficiency anemia and anemia due to blood loss, often prove reversible with treatment of the underlying disorder. Genetic forms of anemia, such as sickle cell anemia, Fanconi anemia and thalassemia, provoke long-standing red blood cell deficiencies.
Chronic Lung Disease
Chronic lung diseases typically interfere with normal absorption of oxygen into the bloodstream. Insufficient absorption can lead to low-level oxygen deprivation in the body tissues and fatigue. Drs. Sean Stitham and Benjamin Medoff note in a Medline Plus entry that common forms of chronic lung disease include emphysema, chronic obstructive pulmonary disease, pulmonary fibrosis, cystic fibrosis and pulmonary edema. Medical interventions for chronic lung diseases that facilitate improved oxygen absorption often help reduce fatigue.
Heart Failure
Heart failure describes the condition wherein the heart cannot pump sufficient blood to meet the body's metabolic needs. The American Heart Association explains that the body prioritizes blood flow to the most vital organs when a failing heart leads to circulatory compromise. Blood flow to the muscles decreases, causing chronic fatigue. With mild to moderate heart failure, physical activity provokes fatigue. People with severe heart failure often have fatigue at rest. Common causes of heart failure and fatigue include coronary heart disease, hypertensive heart disease, valvular heart disease, congenital heart defects and heart muscle diseases.
Sleep Apnea
Breathing pauses during sleep characterize the chronic condition sleep apnea. Pauses vary in duration and frequency. Repetitive breathing pauses throughout the night interfere with normal sleep. According to the National Heart, Lung and Blood Institute, sleep apnea is a leading cause of tiredness. Most sleep apnea occurs due to intermittent airway obstruction; the tissues of the throat block the airway. Excess body weight and obesity increase the risk for obstructive sleep apnea. Central sleep apnea occurs when the breathing control center of the brain fails to send regular signals to produce uninterrupted breathing during sleep. Successful treatment of sleep apnea typically eliminates associated daytime fatigue.
