Most common causes
Obstructive sleep apnea
Depression, anxiety
Deconditioning
Drugs (see below)
Chronic fatigue syndrome, Fibromyalgia
Pregnancy
Anemia
Vessel (flow):
Cardiopulmonary -Obstructive sleep apnea, CHF, COPD, peripheral vascular disease, atypical angina
Myocardial infarction, Heart failure, myocarditis
Celiac disease
Pulmonary, hepatic, renal failure
Anemia
Pulmonary hypertension
Infections:
Endocarditis, tuberculosis, infectious mononucleosis, hepatitis, parasitic disease, HIV, CMV, pneumonia, mastitis, urosepsis, Lyme, Coccidiomycosis, Giardia
Botulism
Black widow spider bite
Neoplasm:
Cancer, lymphoma
Drugs and Diet:
Medication use (e.g., beta-blockers, clonidine, sedative-hypnotics, analgesics, antihypertensives, antidepressants, muscle relaxants, opioids, antibiotics) or
Substance abuse
Endocrine and Electrolytes:
Diabetes mellitus,
hypercalcemia, chronic kidney disease, hepatic failure
Hypothyroidism, hyperthyroidism
Adrenal insufficiency, Addison’s disease
Disturbance of calcium, phosphorus, magnesium
Hypokalemia, hyponatremia
Hypogonadism
Hypopituitarism/pituitary insufficiency
Autoimmune, autoinflammatory, Rheumatologic:
Systemic lupus erythematosus
Polyarteritis nodosa
Polymyalgia rheumatica/Temporal arteritis
Post-Lyme disease syndrome
Wegener’s granulomatosis
Rheumatoid arthritis,
Deficiencies and Excesses:
Vitamin D deficiency
Vitamin B12 deficiency
Environmental:
Carbon monoxide
Musculoskeletal:
Deconditioning
Ehlers Danlos syndrome
Chronic fatigue syndrome, Fibromyalgia
Neuropsychiatric:
Restless legs syndrome
Peripheral neuropathy (diabetes)
Multiple sclerosis
Guillain-Barré syndrome
Myasthenia gravis
Psychological: depression, anxiety, somatization disorder, dysthymic disorder
Disturbed sleep: Obstructive sleep apnea, gastroesophageal reflux disease, allergic or vasomotor rhinitis
Delirium
Parkinson disease
Further Reading
Am Fam Physician. 2008 Nov 15;78(10):1173-1179. http://www.aafp.org/afp/2008/1115/p1173.html