 Estimates of sleep disruption after traumatic brain injury TBI reach 81, but the incidence nature, course and effect on recovery from TBI are not well understood because most TBI sleep studies included mixed TBI severity samples at varied times post injury. In the early rehabilitation phase of recovery from moderate-to-severe TBI, sleep disturbance has been estimated at 78 and has been associated with the presence of post-traumatic amnesia PTA; a transient period of disorientation, confusion and inability to store memories that occurs after TBI. Individuals with TBI who are in PTA not only have severe memory dysfunction that significantly impairs their ability to benefit from verbal instruction, but are often in a confusional state with agitated behavior. They require a 24-hour, highly structured environment for safety until their PTA resolves. PTA can last from days to weeks, during which time the individual and hisher family are significantly distressed. Its duration also has practical implications in terms of resources, length of hospitalization and cost. 