Fatigue is a symptom, not a disease, and it's experienced differently by different people. Fatigue from stress or lack of sleep usually subsides after a good night's rest, while other fatigue is more persistent and may be debilitating even after restful sleep. Harvard's Special Health Report Boosting Your Energy provides advice and information from world-renowned medical experts that can help you discover the cause of your fatigue and find the right treatment or lifestyle changes. Anthony L. Komaroff, M.D., Simcox-Clifford-Higby Professor of Medicine at Harvard Medical School and Senior Physician at Brigham & Women's Hospital