Sleep problems ranged from difficulty falling asleep, sleep-disordered breathing, nightmares, sleepwalking and increased daytime sleepiness, researchers led by environmental health expert Kimberly Yolton found.
The study, which appears in today's online edition of "Pediatrics," is the latest in a series of studies Yolton has conducted looking at the effects of secondhand smoke on children.
For the study, researchers asked parents to estimate how much secondhand smoke their children were exposed to on a daily basis. Parents estimated their children were exposed to secondhand smoke at home from at least five cigarettes a day.
Yolton and her colleagues also measured the level of cotinine, a chemical compound left in the blood after the body breaks down nicotine, in the 219 children included in the study.
The cotinine measure showed children were exposed to a median of 13 cigarettes a day in the home.
Children with higher levels of cotinine showed more signs of sleep problems, Yolton said.
Results showed that 93 percent of the children in the study had sleep disturbances severe enough to require medical attention, and the severity of sleep disturbances found was highest in those children exposed to the highest levels of secondhand smoke.
The results mirror findings in previous research Yolton has done showing children exposed to secondhand smoke were more likely to have problems with cognitive functioning, including reading, math and problem-solving skills.
Another study she did showed children exposed to higher levels of secondhand smoke were more likely to have behavioral problems.
The current study linking secondhand smoke and sleep issues is worrisome because lack of quality sleep is tied to a number of health and behavioral issues.
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