Sleep disorders in patients with traumatic brain injury: a review.

Traumatic brain injury (TBI) is a global problem and causes long-term disability in millions of individuals. This is a major problem for both military and civilian-related populations. The prevalence of sleep disorders in individuals with TBI is very high, yet mostly unrecognized. Approximately 46% of all chronic TBI patients have sleep disorders, which require nocturnal polysomnography and the Multiple Sleep Latency Test for diagnosis. These disorders include sleep apnoea (23% of all TBI patients), post-traumatic hypersomnia (11%), narcolepsy (6%) and periodic limb movements (7%). Over half of all TBI patients will have insomnia complaints, most often with less severe injury and after personal assault, and half of these may be related to a circadian rhythm disorder. Hypothalamic injury with decreased levels of wake-promoting neurotransmitters such as hypocretin (orexin) and histamine may be involved in the pathophysiology of excessive sleepiness associated with TBI. These sleep disorders result in additional neurocognitive deficits and functional impairment, which might be attributed to the original brain injury itself and thus be left without specific treatment.