Veterans who have suffered a traumatic brain injury (TBI) are significantly more likely to develop insomnia and other sleep problems years later compared to their counterparts who have not suffered a brain injury, a new study shows.
Results of a large longitudinal study show that those with TBI were about 40% more likely to develop insomnia, sleep apnea, excessive daytime sleepiness, or another sleep disorder in later years, after adjusting for demographics and medical and psychiatric conditions.
Interestingly, the association with sleep disorders was strongest among those with mild TBI versus a more severe brain injury.
The study showed that the risk for sleep disorders increased up to 14 years after a brain injury, an indicator that “clinicians should really pay attention to sleep disorders in TBI patients both in the short term and the long term,” study investigator Yue Leng, MD, PhD, assistant professor, department of psychiatry and behavioral sciences, University of California, San Francisco, told this news organization.
The study was published online March 3 in Neurology.
First long-term look
TBI is common among veterans, who may have sleep complaints or psychiatric symptoms, but previous studies into the consequences of TBI have examined the short- vs. long-term impact, said Dr. Leng.
To examine the longitudinal association between TBI and sleep disorders, the investigators examined data on 98,709 Veterans Health Administration patients diagnosed with TBI and an age-matched group of the same number of veterans who had not received such a diagnosis. The mean age of the participants was 49 years at baseline, and 11.7% were women. Of the TBI cases, 49.6% were mild.
Researchers used an exposure survey and diagnostic codes to establish TBI and its severity.
Patients with TBI were more likely to be male and were much more likely to have a psychiatric condition, such as a mood disorder (22.4% vs. 9.3%), anxiety (10.5% vs. 4.4%), posttraumatic stress disorder (19.5% vs. 4.4%), or substance abuse (11.4% vs. 5.2%). They were also more likely to smoke or use tobacco (13.5% vs. 8.7%).
Researchers assessed a number of sleep disorders, including insomnia, hypersomnia disorders, narcolepsy, sleep-related breathing disorders, and sleep-related movement disorders.
During a follow-up period that averaged 5 years but ranged up to 14 years, 23.4% of veterans with TBI and 15.8% of those without TBI developed a sleep disorder.
After adjusting for age, sex, race, education, and income, those who had suffered a TBI were 50% more likely to develop any sleep disorder, compared with those who had not had a TBI (hazard ratio, 1.50; 95% confidence interval, 1.47-1.53.)
After controlling for medical conditions that included diabetes, hypertension, myocardial infarction, and cerebrovascular disease, as well as psychiatric disorders such as mood disorders, anxiety, PTSD, substance use disorder, and tobacco use, the HR for developing a sleep disorder was 1.41 (95% CI, 1.37-1.44).
The association with TBI was stronger for some sleep disorders. Adjusted HRs were 1.50 (95% CI, 1.45-1.55) for insomnia, 1.50 (95% CI, 1.39-1.61) for hypersomnia, 1.33 (95% CI, 1.16-1.52) for sleep-related movement disorders, and 1.28 (95% CI, 1.24-1.32) for sleep apnea.
It’s unclear what causes postinjury sleep problems, but it could be that TBI induces structural brain damage, or it could affect melatonin secretion or wake-promoting neurons.
Damage to arousal-promoting neurons could help explain the reason the link between TBI and sleep disorders was strongest for insomnia and hypersomnia, although the exact mechanism is unclear, said Dr. Leng.