Doctors have long known that sleep trouble is common in the first few months after a concussion or other traumatic brain injury. But a study published last week in the journal Neurology found that problems with sleeping can actually last a lot longer and might even be permanent.
Eighteen months later, people who have had a traumatic brain injury may need up to an hour more of sleep per night compared with healthy individuals, according to the new study. Moreover, those who had suffered a brain injury significantly underestimated their own daytime sleepiness and sleep needs, study co-author Lucas Imbach told The Huffington Post.
“Despite the fact that sleep lab examinations revealed marked sleepiness and increased sleep need, [patients who'd had traumatic brain injuries] did not feel any more sleepy than healthy people,” said Imbach, a senior physician in the Clinical Research Priority Program on Sleep and Health in the Department of Neurology at Switzerland's University Hospital Zurich.
Previous work by Imbach and his colleagues showed that sleep problems could last as long as six months after brain injury, but these are the first data that compared patients’ sleep a year and a half down the road with sleep patterns in healthy individuals.
Two-thirds of patients still had excessive daytime sleepiness.
The researchers followed up with 31 patients 18 months after they had suffered a traumatic brain injury and asked them about any changes in their sleep habits, levels of daytime sleepiness and fatigue. The patients also wore actigraphs (wristwatch-like bands that measure sleep) for two weeks, which tracked how long it took them to fall asleep at night and how long they slept overall. And they spent one night in a sleep lab so that researchers could more fully observe them.
The researchers followed up with 31 patients 18 months after they had suffered a traumatic brain injury
For comparison purposes, 42 healthy individuals with no history of traumatic brain injury or sleep disorders were asked the same questions and had the same sleep assessments taken.
Data from the actigraphs revealed that the individuals who'd had brain injuries slept an average of 8.1 hours every day, while the healthy individuals slept an average of 7.1 hours.
To objectively determine daytime sleepiness, researchers used what is called a multiple sleep latency test, which measures if and how long individuals take to fall asleep in a quiet environment with their eyes closed.
“Individuals should be able to stay awake for 20 minutes,” Imbach said. A person who drops off in eight minutes or less is categorized as having excessive daytime sleepiness -- which was the case for 67 percent of the patients with brain injuries compared to only 19 percent of the healthy individuals.
Patients critically underestimated their own sleep problems.
Yet when asked to self-assess, the healthy and the injured groups gave similar answers to questions about how long they slept, how sleepy they felt throughout the day and how fatigued they felt throughout the day.
It was that last finding that really caught the eye of Chris Giza, director of the UCLA Steve Tisch BrainSport Program, who was not involved with the study. “One thing that is a little surprising," he said, "is that the objective measures of disrupted sleep showed differences after [traumatic brain injury], but the subjects themselves underestimated their sleep disturbances.”
“Patients do typically get screened for sleep trouble after brain injury -- but probably not systematically or often enough.”- Chris Giza of the UCLA Steve Tisch BrainSport Program
He noted that patients "do typically get screened for sleep trouble after brain injury -- but probably not systematically or often enough.” Plus, most checklists only ask about a few sleep-related symptoms and the new findings suggest that patients might be underestimating their actual post-injury sleep troubles anyway, he said, which could mean that a lot of problems go unnoticed.
What is concerning is that poor sleep can contribute to many other impairments related to brain injury, Giza added. “Attention, cognition and mood can all be adversely affected by inadequate sleep.”
Because the Swiss study was relatively small, he said, it's too early to make sweeping generalizations for the larger population. “But it warrants careful consideration in practice,” Giza said.
Sleep trouble did not depend on the severity of brain injury.
The study's findings of persistent sleep trouble were consistent across patients with mild and severe brain injuries -- a result that leads to more questions.
It might mean that these types of injuries, regardless of severity, actually cause damage to a part of the brain that helps control sleep, Imbach explained. But that's just a theory, and he said the current study was "not designed to unravel the underlying mechanism of post-traumatic sleep-wake disturbances.”
More research is needed, he said, to understand what is happening in the traumatized brain that causes these sleep problems and whether that damage is truly permanent.
Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at firstname.lastname@example.org.