SATURDAY, May 3, 2014 (HealthDay News) -- New research suggests that kids who are bullied when they're younger may be more likely to suffer from nightmares and night terrors a few years later.
However, bullies themselves don't appear to face any higher risk of disturbed sleep.
"They sleep solidly," said study author Dieter Wolke, a professor of developmental psychology and individual differences at the University of Warwick in England. "That is clearly different than what most people think. They are not disturbed thugs, but calculated manipulators."
The study has weaknesses. Its design doesn't allow researchers to compare the percentages of children -- bullied or not-bullied -- who have bad dreams. And researchers can't be certain that being bullied at a younger age directly causes nightmares a few years later. It's possible that some other factor is responsible.
Still, "there is a clear association" between being bullied and having nightmares and night terrors, the researchers found.
What's a night terror? It's when a child gets "stuck" between stages of sleep and may scream and thrash around. "They're nearly impossible to wake and won't remember the episode the next morning," Wolke said.
For the study, the researchers examined surveys of over 6,400 children in the United Kingdom. The children answered questions about bullying at ages 8 and 10, and about sleep problems at age 12.
Overall, 24 percent of the kids had nightmares and 9 percent had night terrors. Even after the investigators adjusted the statistics in the study so they wouldn't be thrown off by high or low numbers of children who had issues such as psychiatric problems, those who'd been bullied when they were younger were still more likely to have these kinds of sleep problems at age 12.
Not all kids who have nightmares or other sleep problems are being bullied. However, among those who do, the level of extra risk of bullying is "moderate," Wolke said.
Could the nightmares be the problem that contributes to bullying by, say, causing kids to be more anxious and seen as vulnerable? Wolke said the study findings don't suggest that possibility.
Robert Faris, an associate professor of sociology at the University of California, Davis, said the study appears to be valid and fits in with previous research that has linked bullying to stress, anxiety and depression. "It does seem likely that anxiety would play a role in nightmares," he said.
What to do? "It is important for pediatricians and doctors to be aware of this relationship," study author Wolke said, and ask about bullying when kids have sleep problems. "Identifying and helping children who are being bullied would eliminate potential mental health problems in the future," he said.
But Faris pointed out that many victims of bullying -- perhaps more than half -- don't feel comfortable telling their parents about what's going on, often because they feel their parents can't do anything about it.
That may indeed be the case, he said. Still, this study suggests that parents of kids who have chronic nightmares should be aware that this behavior may be a sign that their child is being bullied, Faris said.
What if a parent doesn't think their child will open up? "Don't ask directly about whether they're being bullied, but engage in some more subtle conversations instead," Faris suggested. "And pay attention to what's going on with their interactions with friends."
The findings are to be presented Saturday at the annual meeting of the Pediatric Academic Societies in Vancouver. Research presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
For more about bullying, visit the U.S. Department of Health and Human Services.