Persistent tiredness may be a symptom of anemia, thyroid disease, depression or diabetes. Frequent tiredness may also be a result of rheumatoid arthritis, sleep apnea or chronic fatigue, according to Prevention magazine.
Anemia can be a result of an iron or vitamin deficiency in the body, and the persistent tiredness it causes occurs due to a lack of red blood cells that transport oxygen from the lungs to tissues and cells throughout the body. Thyroid diseases that affect metabolic responses may also induce tiredness, reports Prevention magazine. Hyperthyroidism results in a surplus of thyroid hormone that can accelerate metabolism, and hypothyroidism involves a deficiency of thyroid hormone that slows metabolism. Depression often results in decreased energy, changes in eating or sleeping patterns, and negative emotional responses, which may all contribute to chronic tiredness. Diabetes impairs the body's ability to metabolize glucose and may also lead to persistent tiredness.
Rheumatoid arthritis is an autoimmune disease characterized by the immune system attacking healthy joint tissues in the body, explains Prevention magazine. Irreparable damage to cartilage and bones, fatigue, and low energy levels often accompany the disease, and anemia and thyroid diseases typically accompany rheumatoid arthritis and exacerbate tiredness. Sleep apnea, caused by breathing interruptions during sleep, may also result in persistent tiredness, despite how much sleep an individual may achieve during the night. Chronic fatigue syndrome, which has no known cause, may also produce intermittent bouts of fatigue and result in exhaustion despite little exertion.