sleep apnea
Stroke
Thyroid disease such as hypothyroidismFatigue may also be a side effect of certain medications (e.g., lithium salts, ciprofloxacin); beta blockers, which can induce exercise intolerance; and many cancer treatments, particularly chemotherapy and radiotherapy. Inflammation
Inflammation has been linked to many types of fatigue. Findings implicate neuroinflammation in the etiology of fatigue in autoimmune and related disorders. Diagnosis
One study concluded about 50% of people who have fatigue receive a diagnosis that could explain the fatigue after a year with the condition. In those people who have a possible diagnosis, musculoskeletal (19.4%) and psychological problems (16.5%) are the most common. Definitive physical conditions were only found in 8.2% of cases.If a person with fatigue decides to seek medical advice, the overall goal is to identify and rule out any treatable conditions. This is done by considering the persons medical history, any other symptoms that are present, and evaluating of the qualities of the fatigue itself. The affected person may be able to identify patterns to the fatigue, such as being more tired at certain times of day, whether fatigue increases throughout the day, and whether fatigue is reduced after taking a nap. Because disrupted sleep is a significant contributor to fatigue, a diagnostic evaluation considers the quality of sleep, the emotional state of the person, sleep pattern, and stress level. The amount of sleep, the hours that are set aside for sleep, and the number of times that a person awakens during the night are important. A sleep study may be ordered to rule out a sleep disorder.
Fatigue is different from drowsiness, where a patient feels that sleep is required.Temporary fatigue is likely to be a minor illness like the common cold as one part of the sickness behavior response that happens when the immune system fights an infection. Prolonged
Prolonged fatigue is a self-reported, persistent (constant) fatigue lasting at least one month. Chronic
Chronic fatigue is a self-reported fatigue lasting at least six consecutive months. Chronic fatigue may be either persistent or relapsing. Chronic fatigue is a symptom of many diseases and conditions. Some major categories of conditions that feature fatigue include:

Autoimmune diseases, such as celiac disease, lupus, multiple sclerosis, myasthenia gravis, Sjögrens syndrome, and spondyloarthropathy
Anxiety disorders such as generalized anxiety disorder
Blood disorders such as anemia and hemochromatosis
Cancer, in which case it is called cancer fatigue
Chronic fatigue syndrome (CFS)
Substance use disorders including alcohol use disorder
Depression and other mental disorders that feature depressed mood
Developmental disorders such as autism spectrum disorder
Eating disorders, which can produce fatigue due to inadequate nutrition
Endocrine diseases or metabolic disorders: diabetes mellitus, hypothyroidism and Addison’s disease
Fibromyalgia
Gulf War syndrome
Heart failure
HIV
Idiopathic chronic fatigue (ICF), which is chronic fatigue with no known cause that does not meet chronic fatigue syndrome criteria
Inborn errors of metabolism such as fructose malabsorption. Infectious diseases such as infectious mononucleosis or tuberculosis
Irritable bowel syndrome
Kidney diseases e.g. acute renal failure, chronic renal failure
Leukemia or lymphoma
Liver failure or liver diseases e.g. Hepatitis
Lyme disease
Neurological disorders such as narcolepsy, Parkinsons disease, Postural Orthostatic Tachycardia Syndrome and post-concussion syndrome
Physical trauma and other pain-causing conditions, such as arthritis
Sleep deprivation or sleep disorders, e.g.