Tiredness is a thing that is experienced by all of us, and it does get away by sleeping adequately or by resting for some time. But fatigue is something different, and, most of the time, overwhelming, which cannot be driven away by sleeping or taking rest. Fatigue can also be a sign of some severe health issues that can bother you even more in the long run. There can be several medical reasons behind the problem of fatigue in a person. Here is a list of some of the common medical reasons that can cause fatigue in a person.