Post-traumatic Sleep following Diffuse Traumatic Brain Injury

OF DISSERTATION POST-TRAUMATIC SLEEP FOLLOWING DIFFUSE TRAUMATIC BRAIN INJURY By Rachel Kathleen Rowe Traumatic brain injury (TBI) is a major cause of death and disability throughout the world with few pharmacological treatments available for individuals who suffer from neurological morbidities associated with TBI. Cellular and molecular pathological processes initiated at the time of injury develop into neurological impairments, with chronic sleep disorders (insomnia, hypersomnolence) being among the somatic, cognitive and emotional neurological impairments. Immediately post-injury, TBI patients report excessive daytime sleepiness, however, discordant opinions suggest that individuals should not be allowed to sleep or should be frequently awoken following brain injury. To provide adequate medical care, it is imperative to understand the role of acute post-traumatic sleep on the recovery of neurological function after TBI. The aim of this thesis was to examine post-traumatic sleep after experimental TBI, defined as an increase in sleep during the first hours post-injury. In these studies, we non-invasively measured sleep activity following diffuse brain injury induced by midline fluid percussion injury to examine the architecture of post-traumatic sleep in mice. We detected significant injury-induced increases in acute sleep for six hours regardless of injury severity or time of day injury occurred. We found concurrent increases in cortical levels of the sleep promoting inflammatory cytokine interleukin 1beta. We extended the timeline of post-injury sleep recording and found increases in post-traumatic sleep are distinctly acute with no changes in chronic sleep following diffuse TBI. Further, we investigated if post-traumatic sleep was beneficial to neurological outcome after brain-injury by disrupting post-traumatic sleep. Disruption of post-traumatic sleep did not worsen functional outcome (neuromotor, sensorimotor, cognition) at one week after diffuse TBI. With sufferers of TBI not always seeking medical attention, our final studies investigated over-the-counter analgesics and their effect on post-traumatic sleep and functional outcome. Acute administration of analgesics with varying anti-inflammatory properties had little effect on post-traumatic sleep and functional outcome. Overall, these studies demonstrated translational potential and suggest sleep after a concussion is part of the natural recovery from injury. While disrupting sleep does not worsen outcome, it is in no way beneficial to recovery. Additionally, a single analgesic dose for pain management following concussion plays little role in short term outcome.