<qa>  What is the relationship between sleep disturbance and PTA during early recovery from TBI?There appears to be a relationship between sleep disturbance and PTA during early recovery from TBI, but the nature of the relationship is not fully understood. Sleep disturbance has been associated with delirium in non-TBI medical patients, and sleep deprivation has been associated with significant negative effects on attention, reaction time, visual-motor performance, language functions, memory processes, and executive functions in normal populations. Sleep disturbance appears to negatively affect cognitive functioning in both medical and normal samples. In the TBI population, sleep disruption could further exacerbate the already compromised cognitive functions and prolong PTA. The relationship between sleep disruption and PTA presents a potentially significant therapeutic opportunity because PTA is largely considered to be fixed and immutable with no therapeutic options. Therapeutic efforts to improve sleep may reduce the length of PTA. 