Abbreviations: CBT = cognitive-behavioral therapy, CBT-I = CBT for insomnia, EEG = electroencephalography, PTSD = posttraumatic stress disorder, REM = rapid eye movement, TBI = traumatic brain injury, VA = Department of Veterans Affairs.
SLEEP DISTURBANCES IN TRAUMATIC BRAIN INJURY: RELEVANCE TO VETERANS
Sleep disturbances, such as insomnia, are very common following traumatic brain injury (TBI) and have been reported in frequencies up to 84 percent (Table). Sleep disruption can be related to the TBI itself but may also be secondary to neuropsychiatric (e.g., depression, anxiety) or neuromuscular (e.g., pain) conditions associated with TBI or to the pharmacological management of the injury and its consequences (Figure). Sleep disturbances in TBI may affect or exacerbate psychiatric problems, memory, mood, behavior, and social functioning. Sleep disruption has been shown to hinder overall rehabilitation from TBI and is suggested to have a negative effect on the neural remodeling necessary for recovery from many types of brain injuries . Although increased awareness of the potential negative contribution of sleep disorders to poorer outcome in TBI exists, further studies are necessary to generate additional objective data on these patients in terms of the prevalence, clinical features, types of sleep problems, and relationships between the severity of the TBI and sleep disorders and between sleep disorders and other psychiatric problems, as well as the appropriate treatments for these conditions.
This review focuses on insomnia in the context of TBI. Thus, we will consider insomnia directly caused by TBI (e.g., secondary to neural damage), insomnia indirectly caused by TBI (e.g., secondary to depression), and insomnia unrelated to TBI but occurring in individuals with TBI as being in the context of TBI. In the TBI and sleep literature, these three etiologies are generally not clinically parsed. Insomnia is the most common disorder of sleep in the general population and has even higher prevalence in those who have experienced a TBI . Sleep apnea (i.e., sleep-disordered breathing) is also a prevalent disorder in the general population that leads to disruption of nocturnal sleep and to daytime sleepiness. Given the demographics of veterans, sleep apnea exists commonly in this population . A direct connection between sleep apnea and TBI is unlikely, though sleep apnea will likely compound the difficulties in TBI rehabilitation. Several case studies and reports have also described narcolepsy, another sleep disorder found in <5 percent of the general population, in those with TBI [4-6]. These TBI-induced narcolepsy cases are likely due to a disruption of the hypocretin neurotransmitter system localized in the lateral hypothalamus . An extended discussion of narcolepsy, however, is beyond the scope of this review.
Sleep can be characterized by both subjective and objective measures. However, inconsistency between these two measures often characterizes sleep pathology. For example, sleep apnea, present in about half the Department of Veterans Affairs (VA) patient population, can be readily characterized using objective measurements of breathing and electroencephalography (EEG) during an overnight sleep episode . Yet many individuals who, on objective measures, have severely disturbed sleep because of sleep apnea often fail to realize that their sleep is disturbed; more often they describe poor daytime alertness. Likewise, many individuals who complain of insomnia have normal sleep when measured by EEG. According to the International Classification of Sleep Disorders, insomnia is defined as a subjective complaint of difficulty initiating or maintaining sleep, waking up too early, or having nonrestorative sleep despite adequate opportunity for sleep . The dichotomy between the complaint of insomnia and a laboratory finding may result from a failure of recording and analytic techniques to accurately describe the physiologic abnormality that underlies this feeling of insomnia. …