Fatigue is one of the more commonly reported symptoms associated with brain injury (Duclos et al. 2014; Elovic et al. 2005) and can exacerbate other co-morbidities. One of the greatest challenges is in properly defining fatigue; a clear definition is integral to determining how it should be measured and managed. It is believed that fatigue is a subjective experience and thus is not easily assessed by objective measures (Lewis & Wessely 1992). This section reviews fatigue and sleep disorders in more depth.