At least 18 months after sustaining a traumatic brain injury, first-time concussion victims continue to need more sleep and to suffer more daytime sleepiness than do healthy people, says new research. But even as they run higher risks of such injuries as vehicle crashes, sufferers routinely underestimate both their sleepiness and their increased sleep need, the study finds.
Experts in neurotrauma have long known that the concussed brain needs extra rest to heal, even as patients' sleep-wake cycles are disrupted by the injury. In the weeks following a serious blow to the head, patients are urged to get extra sleep, and to limit their physical and cognitive exertion.
Some of the most troublesome signs of traumatic brain injury--headache, dizziness, irritability, memory and vision problems--tend to subside, for most, in a few weeks. But the new research suggests that, while subtle, sleep problems can persist long after that, even for those whose initial symptoms were not so severe.
On average, 1½ years after their brain injury, subjects slept 8.1 hours per night vs. 7.1 hours for healthy controls. Even with that extra hour, they were more tired during their wakeful hours, as measured by how quickly they fell asleep.
The new study, conducted in Switzerland, was published online Wednesday in the journal Neurology. It appears to be the longest prospective study about sleep quality and TBI published to date. Researchers conducted nightlong sleep studies, tracked subjects' sleep with devices worn on the wrist, performed structured interviews about sleep and daytime wakefulness, and measured how quickly subjects fell asleep when their heads hit the pillow (a measure of excessive daytime sleepiness).
Six months after sustaining a blow to the head, subjects whose traumatic brain injuries were judged most severe needed more sleep than did those with less severe injuries. But at 18 months out, that distinction disappeared: compared to healthy control subjects, average sleep-need remained consistently higher among the study's 20 subjects with traumatic brain injury, whether they had had intra-cranial bleeding or not.
While 19% of the healthy control subjects suffered from excessive daytime sleepiness, 67% of those with TBI did. When they were asked how sleepy they were during the day, those with TBI didn't report feeling any sleepier than those without TBI.
"Our data suggest that post-traumatic sleep-wake disturbances transform into a chronic state of disease in a majority of patients with TBI," the authors of the current study wrote. Traumatic brain injuries differ in severity. But research increasingly suggests that almost all who suffer ill effects of a blow to the head may have experienced shearing and stretching of the fatty connective tissue that speeds electrical signals among neurons and throughout the brain. That, in turn, may disrupt the delicate dance of signals that promote sleep and wakefulness throughout the brain.
Even if they're unaware of excessive daytime sleepiness, patients who have ongoing difficulties in the wake of a concussion might need to spend a night in a sleep lab where disruptions in sleep-wake patterns can be diagnosed, they suggested.
Lead author Dr. Lukas Imbach, of the University Hospital Zurich, said the study's findings make a compelling case that sleep-wake disorders after TBI may represent "a silent epidemic." Long after a patient's brain appears to have healed, he said, trouble persists.
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