<unk>  is a normal result of work, mental stress, anxiety, overstimulation and understimulation, jet lag, active recreation, boredom, lack of sleep or disease. Acute Causes of acute<unk>  include depression; chemical causes, such as dehydration, poisoning, low blood sugar, or mineral or vitamin deficiencies.<unk>  is different from drowsiness, where a patient feels that sleep is required. Temporary<unk>  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<unk>  is a self-reported, persistent (constant)<unk>  lasting at least one month. Chronic Chronic<unk>  is a self-reported<unk>  lasting at least six consecutive months. Chronic<unk>  may be either persistent or relapsing. Chronic<unk>  is a symptom of many diseases and conditions. Some major categories of conditions that feature<unk>  include: * Autoimmune diseases, such as celiac disease, lupus, multiple sclerosis, myasthenia gravis, Sjögren's 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<unk>  * Chronic<unk>  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<unk>  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<unk>  (ICF), which is chronic<unk>  with no known cause that does not meet chronic<unk>  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, Parkinson's 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. sleep apnea * Stroke * Thyroid disease such as hypothyroidism<unk>  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<unk> . Findings implicate neuroinflammation in the etiology of<unk>  in autoimmune and related disorders.
Fatigue
Altitude sickness
Sedation
Idiopathic chronic fatigue
Personality changes
Neurosis
Somnolence
Anorexia 