Fatigue is a term used to describe an inclusive feeling of tiredness or lack of energy. It isn’t the same as simply feeling sleepy or sleepy. When you’re fatigued, you have no stimulation and no energy. Being sleepy may be a sign of fatigue, but it’s not the same thing. Fatigue is a common symptom of many medical conditions that compass in severity from mild to serious. It’s also a natural result of some lifestyle option, such as lack of exercise or poor diet. If your fatigue doesn’t settle with proper rest and nutrition, or you suspect it’s caused by an underlying physical or mental health state, see your doctor. They can help determine the cause of your fatigue and work with you to treat it.