Some common physiological causes of fatigue include anemia, medication side effects, chronic pain, sleep disorders and thyroid dysfunction. Because of the large number of illnesses that can cause this symptom, a doctor should take a thorough history and physical to help make an accurate diagnosis, according to MedlinePlus.
When determining the cause of fatigue, additional symptoms should be considered. If a person wakes up full of energy in the morning and the fatigue occurs a few hours later, the diagnosis can be caused by decreased thyroid function. If the fatigue begins in the morning and continues throughout the day, the cause can be depression.
Because blood pressure pills, antihistamines, steroids, sleeping aids and diuretics can all cause fatigue, it's important for individuals to talk with the prescribing physician before making a decision to change or stop theses medication.
MedlinePlus recommends that a person seek immediate medical help if fatigue is accompanied by dizziness, blurry vision or changes in urination. In this situation, a doctor will check the heart, abdomen, thyroid and lymph nodes and order laboratory tests, such as blood work, to check for anemia and thyroid function.
If disease is not the cause of a person’s fatigue, lifestyle modification techniques can help increase energy. These include changing sleeping habits, eating healthy, exercising and avoiding tobacco and alcohol products, according to MedlinePlus.