Fatigue is a lack of energy or feeling of debilitating tiredness. It may be a normal physical response to factors such as:

• Lack of sleep
• Physical exertion
• Stress or anxiety
• Depression or grief
• Boredom
• Certain medications, such as for high blood pressure or cancer

Fatigue associated with these factors may last days, weeks or months. It often disappears after the patient becomes rested. It is also a common symptom of pregnancy, and of minor illnesses such as colds.

Fatigue can also be due to many serious or long-term diseases ranging from diabetes to fibromyalgia. This fatigue may not be relieved as easily.Such patients may experience chronic fatigue, often defined as lasting six months or longer . Chronic fatigue can impede on normal functioning and interfere with a patient's ability to:

• Concentrate at work or school
• Perform household tasks
• Maintain normal relationships
• Derive pleasure from favorite activities

Patients who have chronic fatigue and meet certain other diagnostic criteria may be diagnosed with chronic fatigue syndrome.

Recent research indicates that disabling short-term and long-term fatigue may have genetic roots and tend to run in families.

Fatigue can impair memory, trigger headaches, induce muscle pain and cause accidents. Even though fatigue can greatly affect patients’ lives, many individuals do not report it to healthcare professionals. Patients experiencing fatigue are encouraged to discuss the condition with their physician, who can determine the possible cause.