Chronic fatigue syndrome
Though the causes of chronic fatigue syndrome (CFS) have long been unknown, researchers recently discovered a link between the debilitating condition and lower levels of certain thyroid hormones. In one study published in the journal Frontiers in Endocrinology, scientists concluded that patients diagnosed with chronic fatigue syndrome had lower levels of two key thyroid hormones—triiodothyronine (T3) and thyroxine (T4)—compared to those without the sleep-related syndrome. The researchers believe that these decreased hormone levels could be contributing to CFS symptoms.