Objective: To examine sleep and wake disorders following traumatic brain injury (TBI) and their impact on recovery of cognition, communication and mood. Research Design: This three-manuscript thesis comprises an introduction to sleep in the context of human function and development. It is followed by a systematic review of the literature pertaining to sleep and wake disorders following TBI, and then explores the relationship between sleep and arousal disturbance and functional recovery of cognitive-communication through a single case study, pre–post intervention. Finally, a larger study longitudinally explores the impact of treatment to optimize sleep and wakefulness on recovery of cognition, communication and mood through objective and subjective measures, pre-post intervention. The thesis concludes with a chapter that addresses the implications of findings for rehabilitation from the perspective of the International Classification of Functioning, Disability and Health (ICF), and a presentation of future research directions for the field Methods: The first manuscript involved a systematic review and rating of the quality of evidence. The second manuscript involved the evaluation of sleep and wakefulness by objective measures, and longitudinally by self-report through the Daily Cognitive-Communication and Sleep Profile (DCCASP, © Wiseman-Hakes 2008, see Appendix S). Cognitive-communication abilities were also measured by the DCCASP. The third manuscript utilized a single case series and cohort design to evaluate sleep and wakefulness, and to examine cognition, communication and mood at baseline and following optimization of sleep and wakefulness. Results: For Manuscript One, 43 articles were reviewed for levels and quality of evidence across 5 domains: epidemiology, pathophysiology, neuropsychological implications, intervention and paediatrics. In Manuscript Two, we showed that there was a statistically and functionally significant relationship between perceived quality of sleep and language processing, attention and memory, seen across the phases of the intervention. In Manuscript Three, we showed that there were statistically and functionally significant improvements across several domains of cognition, communication and mood in response to treatment. Conclusions: Sleep and wake disorders after TBI are pervasive, and can negatively impact rehabilitation and recovery. There is a need for systematic evaluation and intervention for these disorders in all persons with TBI.

Objective: To examine sleep and wake disorders following traumatic brain injury (TBI) and their impact on recovery of cognition, communication and mood. Research Design: This three-manuscript thesis comprises an introduction to sleep in the context of human function and development. It is followed by a systematic review of the literature pertaining to sleep and wake disorders following TBI, and then explores the relationship between sleep and arousal disturbance and functional recovery of cognitive-communication through a single case study, pre–post intervention. Finally, a larger study longitudinally explores the impact of treatment to optimize sleep and wakefulness on recovery of cognition, communication and mood through objective and subjective measures, pre-post intervention. The thesis concludes with a chapter that addresses the implications of findings for rehabilitation from the perspective of the International Classification of Functioning, Disability and Health (ICF), and a presentation of future research directions for the field Methods: The first manuscript involved a systematic review and rating of the quality of evidence. The second manuscript involved the evaluation of sleep and wakefulness by objective measures, and longitudinally by self-report through the Daily Cognitive-Communication and Sleep Profile (DCCASP, © Wiseman-Hakes 2008, see Appendix S). Cognitive-communication abilities were also measured by the DCCASP. The third manuscript utilized a single case series and cohort design to evaluate sleep and wakefulness, and to examine cognition, communication and mood at baseline and following optimization of sleep and wakefulness. Results: For Manuscript One, 43 articles were reviewed for levels and quality of evidence across 5 domains: epidemiology, pathophysiology, neuropsychological implications, intervention and paediatrics. In Manuscript Two, we showed that there was a statistically and functionally significant relationship between perceived quality of sleep and language processing, attention and memory, seen across the phases of the intervention. In Manuscript Three, we showed that there were statistically and functionally significant improvements across several domains of cognition, communication and mood in response to treatment. Conclusions: Sleep and wake disorders after TBI are pervasive, and can negatively impact rehabilitation and recovery. There is a need for systematic evaluation and intervention for these disorders in all persons with TBI.

Conversation is a highly interactive and coordinated effort between interactants. For example, interactants often mimic the behaviors and speech of one another and coordinate the timing of behaviors, or interactional synchrony. Despite being affected in certain neurological and psychiatric disorders, the neural mechanisms underlying these processes are not understood. The goal of this study is to understand the role of the ventromedial prefrontal cortex (vmPFC), an area of the brain involved in social and emotional behavior, for interpersonal coordination, including mimicry and interactional synchrony. To test the role of the vmPFC for mimicry, normal comparison (NC), brain damaged comparison (BDC), and participants with vmPFC damage interacted in two sessions with a research assistant (RA) who was performing a target behavior (1st session: nodding, 2nd session: face touching). The amount of time the participants spent nodding or touching their face in each session was recorded. NC and BDC participants tended to mimic the partner and nodded slightly more in the session in which the RA was nodding, and touched their face slightly more in the session in which the RA was touching their face. In contrast, vmPFC patients showed no difference in their behaviors in either session, suggesting that they were not influenced by the partner's behaviors and did not mimic them. In a second experiment, all of the above participant groups had a naturalistic conversation with an unfamiliar interactional partner. The conversational data were analyzed for numerous aspects of interpersonal coordination, including convergence of number of words, words per turn and backchannels, reciprocity of self-disclosures, the use of questions, interactional synchrony, and a time series analysis of response latency and speech rate. The vmPFC participants performed consistently worse than NC participants on convergence of words and words per turn, self-disclosures and asking questions. All brain-damaged participants were impaired on aspects of interactional synchrony, and no conclusive results were found for the time series analysis of response latency and speech rate. This study provides support for the hypothesis that the vmPFC is important for interpersonal coordination as the vmPFC group differed significantly from the NC group on the majority of the analyses. The final goal of this study was to understand the effects of traumatic brain injury (TBI) on interpersonal coordination. TBI patients participated in all of the experiments described above and preliminary results showed that they also seemed to be impaired on the mimicry task, and they performed slightly worse than NC participants on many of the interpersonal coordination analyses of the conversational data. This suggests that TBI also does seem to affect certain aspects of interpersonal coordination.