MIAMI BEACH — More than one-fourth of youngsters who suffer a minor head injury may develop chronic sleep problems ranging from frequent awakenings to nightmares. In some cases, this can lead to problems of learning and concentration, new research shows.
In a study of nearly 200 adolescents, 28 percent of those who suffered a mild head injury reported in questionnaires that they had persistent sleep disturbances, compared with 11 percent of those who had not hurt their heads. The difference was highly significant. Overweight youngsters and those whose parents failed to complete high school were at highest risk.
“Even after a long time has passed, adolescents who had had a head injury that looked trivial might have sleep problems that can affect their quality of life and interfere with daytime functioning,” said Sarit Ravid, MD, a child neurologist at Rambam Medical Center in Haifa, Israel, who presented the findings.
MILD HEAD INJURY NOT BENIGN
“Mild head injury may not be as benign as previously estimated,” she told Neurology Today during a poster session here at the October meeting of the Child Neurology Society (CNS). “If sleep problems start, treatment should be instituted right away to prevent an acute problem from becoming chronic.”
A minor head injury, defined as a brain concussion commonly associated with transient loss or impairment of consciousness for less than 20 minutes, vomiting, and a short anterograde or retrograde amnesia, is a common event among children and adolescents, Dr. Ravid said. In these cases, the estimated Glasgow Coma Scale score is 13 or higher. CT and MRI, EEG, brainstem auditory evoked responses, and audiograms are commonly normal or show only minor transient abnormalities, she said.
“There have been complaints of difficulties in initiating and maintaining sleep, early morning awakenings, decreased daytime performance, and a generally decreased sleep quality,” Dr. Ravid said. “But only a few studies have attempted to use objective measures of sleep behavior patterns following mild head injury or to assess the long-term effects on sleep patterns in adolescents.”
The researchers enrolled 98 children, ages 7 to 15 years, who had been admitted to the emergency room six months to six years previously with a mild head injury. Eighty youngsters matched for age, gender, and body mass index with no known history of head trauma were randomly selected at local schools as controls.
All youths completed 60-item questionnaires, which asked about their family history, general health status, any complaints associated with the head injury, and their sleep quality. The quantitative questions instructed the participant to grade each answer on a 4-point scale, with 0 corresponding to “never” and 4 to “always.”
A child was considered to suffer from a sleep disorder if the summary score of the following eight questions regarding sleep quality exceeded 12 points: frequent awakenings from sleep, difficulty falling asleep, frequent moving during sleep, early morning awakenings, anxiety and arousal from sleep, non-restorative sleep, bad dreams, and daytime somnolence, Dr. Ravid said.
The average score of sleep complaints was significantly higher in the study group than the control arm: 10.1 versus 8.2 (p > 0.05), she said. Also, 10 percent of teens who suffered a head injury suffered from sleep bruxism (grinding the teeth), compared with 4 percent of their non-injured counterparts (p < 0.05), the study showed.
There were no differences between the groups with respect to other sleep disturbances such as sleepwalking or nocturnal enuresis, Dr. Ravid reported. And while no significant differences were found between the groups regarding bedtimes, wake-up times, or number of hours spent sleeping on weeknights, those who had a head injury slept less on weekends: 9.7 hours versus 10.3 hours for controls, the study showed.
“This was surprising,” Dr. Ravid said. “If indeed their sleep is disrupted during weekdays it could have been expected that their time in bed during weekends would increase. We believe that, in the case of this study, adolescents from the study group suffered from the inability to extend their sleep on weekends.”
EMOTIONAL, LEARNING DIFFICULTIES
Other symptoms commonly associated with emotional stress, such as anxiety and headaches, were also more prevalent in adolescents who had a mild head injury than in controls, she said.
“Although most of the youngsters have managed to function properly in everyday life despite the reported disrupted sleep patterns, a few complained of increased daytime somnolence, preventing them from attending school; learning and concentration difficulties; anxiety; and recurrent headaches that required medical attention,” Dr. Ravid said.
The youngsters with head trauma were then divided into two subgroups: those with sleep disturbance and those who slept peacefully through the night. Two-tailed unpaired t-tests and correlation analyses showed that youngsters with sleep disturbances had a significantly higher body mass index: a mean of 20.8 kg/m2, compared with 18.4 kg/m2 for controls.
“To the best of our knowledge, the [finding that] heavier adolescents are at increased risk for the development of long-term sleep complaints following mild head injury has not been previously reported and the reasons remain open,” Dr. Ravid said. “We can only speculate that heavier adolescents may suffer from lower self-esteem that may predispose them to sleep disturbances.”
EDUCATION A FACTOR
Sleep disturbances were also associated with less parental education, the study showed. The fathers and mothers of children with sleep problems completed an average of 11.0 and 11.8 years of school, respectively, compared with 13.4 and 13.2 years for those who did not suffer sleep disturbances.
Several other studies have also shown an association between poorer parental education and decreased sleep quality in their children, Dr. Ravid said. She speculated that children of less educated parents may be more prone to develop emotional distress and anxiety, and therefore unable to implement techniques to cope with the stress of a head injury.
While the study was not designed to find out why some youngsters with minor head injuries might suffer chronic sleep problems, Dr. Ravid offered several hypotheses.
“Quite a few adolescents reportedly develop sleep disturbances within the acute stage of mild head injury,” she said. “With lapsing time, when sleep disturbances improve, these adolescents may have already developed secondary emotionally derived insomnia.
“In this disorder, the acute stress, instead of resolving with time, leads to substantial concern and distress now focusing on the sleep itself. A vicious cycle of poor sleep leading to further anxiety regarding insomnia is created.”
This explanation is supported by the fact that these youngsters were more likely to report gritting their teeth, she said. Stress can lead to bruxism, which in turn may result in sleep fragmentation and further non-restorative sleep, she explained.
Another possible explanation may be a premorbid personality, which may result in sleep disturbances following a relatively minor trauma, according to Dr. Ravid.
Regardless of the explanation, neurologists should be aware that teens can develop chronic sleep problems following mild head trauma, she said. “Treatment should be given in time before learning disability and impaired development occur.”
Donald L. Gilbert, MD, Assistant Professor of Child Neurology at Children's Hospital Medical Center in Cincinnati, OH, said, “The study is interesting and certainly warrants follow-up. But because the children were first observed post-injury, it is difficult to know which came first: the sleep problems or the trauma,” he said.
“I would be interested in knowing if the children had attention deficit hyperactivity disorder [ADHD] prior to the injury, for example,” he said. Children with ADHD are prone to both sleep disturbances and head trauma, he explained. In fact, any child who is not properly rested may be at heightened risk of injury, Dr. Gilbert said.
Dr. Ravid agreed that such a possibility exists and said her team is currently attempting to address that question. “We're trying now to go back to the schools to see if the children had ADHD, anxiety, or other health problems that would predispose to head injury and sleep disturbances,” she said.
Also worthy of further research is whether sleep problems are the consequence of a direct injury to the head or whether they develop, as a result of emotional distress, following any trauma, Dr. Ravid said.
ARTICLE IN BRIEF:
✓ In a study of nearly 200 adolescents, 28 percent of those who suffered a mild head injury reported that they had persistent sleep disturbances, compared with 11 percent of those who had not hurt their heads. The difference was highly significant.
✓ Overweight youngsters and those whose parents failed to complete high school were at highest risk.