Sleep Disorders in Traumatic Brain Injury

The Range of Sleep Disorders in TBI

Sleep disturbances are exceedingly common in the TBI population. Subjective complaints of sleep-wake disturbances occur in 30%-70% of those with TBIs.^{[4,5,6,7,8,9]} Such complaints include sleep fragmentation, insomnia, impaired daytime functioning, and hypersomnolence.^[10]Sleep-disordered breathing (SDB) occurs in up to 35% of patients with TBI, compared with 4%-9% in the general population.^[11] Similarly, periodic limb movement disorders (PLMD) has a significantly higher prevalence among those with TBI, and is reported to be as high as 25.4% in TBI patients vs 5% in the general population.^[12]

The range of sleep disorders described in the TBI population includes:

Post-traumatic hypersomnia (PTH);
Post-traumatic narcolepsy;
Parasomnias (particularly rapid eye movement [REM]-behavioral disorder);
Delayed sleep phase syndrome or other circadian rhythm disturbances;
Insomnia;
Daytime fatigue;
Alteration of sleep-wake schedule;
PLMD;
Nocturnal seizures; and
Sleep apnea syndrome, including obstructive, central, and mixed apneic events.^[2]

Sleep Apnea and Excessive Daytime Somnolence

The current literature on sleep disorders in TBI patients includes studies that evaluate objective conditions (sleep apnea), as well as those that assess subjective sleep complaints (excessive daytime somnolence), often using surveys. Most studies assessing sleep disorders in TBI patients cite prevalence rates significantly higher than those found in the general population. In a study of 10 randomly selected TBI patients whose subjective complaints would not otherwise have required an investigation for sleep-related disorders, the investigators found that all 10 had abnormal sleep.^[13]Seven individuals had SDB, 5 of whom had obstructive sleep apnea (OSA), 1 had REM-related OSA, and 1 was found to have upper airway resistance syndrome. Two individuals were found to have post-traumatic narcolepsy and PTH was observed in 1 patient.^[12] In a retrospective study of 60 adults with TBI (40% mild severity, 20% moderate, 40% severe), 50% reported daytime hypersomnia.^[4] In this cohort, 30% were diagnosed with OSA, 25% with insomnia, and 25% with parasomnias, the most frequent of which was REM-behavior disorder.^[4]

Baumann and colleagues evaluated 96 patients 4 days post-injury.^[13] Re-evaluation was conducted 6 months post-injury in 65 individuals. Patients were comprehensively evaluated with subjective-questionnaire data, neuroimaging, laboratory studies, and objective measures of sleep, including overnight polysomnography, multiple sleep latency testing (MSLT), maintenance of wakefulness testing, and actigraphy. Most (72%) were found to have new-onset sleep disorders following injury. Subjective daytime somnolence was reported in 28%, and 17% complained of daytime fatigue. Hypersomnolence was confirmed with MSLT in 25%, and 22% met criteria for PTH.^[13]

Wilde and colleagues^[14] assessed the impact of sleep disturbances on cognition in a clinical trial comparing 19 patients with TBI and OSA to 16 patients with only TBI. The 2 groups were comparable with respect to age, education, presenting Glasgow coma scale, and time post-injury. Patients with TBI and OSA performed worse on measures of verbal and visual delayed recall, and comparably on motor, visual construction, and attention tasks. More lapses in attention were found in patients with both conditions. Overall, this study showed that OSA in patients with TBI leads to significantly greater impairment of sustained attention and memory in this already affected population.

In 2007, Castriotta and colleagues^[15]published results from a prospective study of 87 patients who were at least 3 months post-TBI. Polysomnography was abnormal in 46%. Of these, 23% were found to have OSA, 11% had PTH, 6% had post-traumatic narcolepsy, and 7% had PLMD. The study found no correlation between subjective and objective measures of sleepiness and no statistically significant differences in age, race, sex, level of education, injury severity, or time after injury between those with and without concomitant sleep disorders.^[15]

PTH is common following TBI, particularly within the first 24 hours post-injury. The diagnosis requires an increased need for sleep following injury, objective documentation of sleepiness by MSLT, and exclusion of other causes of sleepiness.^[7] The presence of hypersomnia can impair learning and have adverse affects on the rehabilitative process in patients with TBI. Similarly, other pathologic causes of sleepiness, particularly OSA, have clearly been shown to correlate with cognitive deficits and impaired vigilance.^[12]

Insomnia and Circadian Rhythm Sleep Disturbances

Difficulties with sleep initiation and maintenance are among the most frequent complaints in patients with TBI. Insomnia is reported by 30%-65% of affected patients, and is especially common those with mTBI.^{[13,16,17,18,19]} Insomnia can persist up to 3 years post-injury.^[13] Most studies do not clearly differentiate between patients with an objectively defined insomnia syndrome and subjective complaints that are concerning for insomnia.^[19] Ouellet and colleagues evaluated insomnia in 452 TBI patients.^[20] They carefully defined insomnia syndrome, using a combination of the diagnostic criteria presented in the International Classification of Sleep Disorders and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).^[21,22] Insomnia was identified if patients had either a sleep latency of more than 30 minutes or nocturnal awakenings totaling more than 30 minutes.^[20] The study included 452 patients, 50.2% of whom had symptoms of insomnia and 29.4% met criteria for insomnia syndrome. For comparison, the societal prevalence of insomnia is estimated to be 9%-12%.^[20] The investigators observed that insomnia symptoms typically began within a few days following injury and therefore may represent an acute reaction to TBI.

Circadian rhythm disruptions are also common following TBI. In a study by Ayalon and coworkers, patients with mTBI were evaluated for the presence of circadian rhythm sleep disorders (CRSD).^[19] In this study, 80.9% complained of difficulty falling asleep and 19% reported frequent nocturnal awakening. More than one third (36%) were diagnosed with a CRSD. Of these, 53.3% were found to have delayed sleep phase syndrome and 46.7% had an irregular sleep-wake pattern. In comparison, the prevalence of CRSD is 7%-10% in patients with insomnia and less than 2% in the general population.

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