Sleep-related problems are among the most disabling consequences of TBI, with multiple influences: impairment of neuronal plasticity, metabolomic alterations, loss of vascular homeostasis, and disruption of the blood-brain barrier. Moreover, patients with TBI sleep disturbances are more sensitive to pain; are at greater risk for neuropsychiatric problems, such as depression and anxiety; perform poorly on neuropsychological tests of memory, attention, and executive function; and have worse social functioning. They have longer hospitalization stays and once discharged from the hospital are at increased risk for suicide.
The sleep-wake cycle depends on the coordinated function of multiple brain regions, including the brain stem, basal forebrain, hypothalamus, and the frontal-subcortical system, as well as a balance between the arousal activating and inhibitory systems (Figure). CT and other structural imaging devices can miss sleep-associated microstructural abnormalities in the brain. For example, in one study, CT scans did not pick up any brain damage, but when polysomnography was done, significant differences in electroencephalogram power spectra data were seen. The causes of sleep disturbances after TBI are not well understood. However, the mechanisms underlying sleep-wake cycle problems may include the disruption of neural circuits as well as a myriad of other medical and psychiatric disturbances and environmental factors.