Children in the U.S. appear to be getting as much shut-eye as the Centers for Disease Control and Prevention (CDC) recommends, according to a new study.
"We can't say this is the amount that they should be sleeping," said Jessica Williams, the lead author of the study and a graduate student at the University of California, Los Angeles.
"All we could really do is compare our estimated norms with what is recommended, and it seems like it falls pretty well in line with the recommendations," she told Reuters Health.
Williams and her colleagues point out in their study, published in the Archives of Pediatrics and Adolescent Medicine, that there has been concern that U.S. kids are getting too little sleep.
Insufficient sleep has been tied to all sorts of issues in kids and teens, from behavior problems to heart health risks (see Reuters Health reports of October 2, 2012 and October 16, 2012).
But there isn't a lot of hard evidence on how much shut-eye children typically get, Williams said, so the group set out to get an estimate of average sleep duration from birth to age 18.
The researchers gathered data from a nationwide survey that has tracked families for decades.
For this study, they focused on parents' reports of their children's sleep, beginning in 1997.
At the time, 2,832 children were included. In 2002 and 2007 the families were surveyed again and there were 2,520 and 1,424 children included, respectively.
Dr. Maurice Ohayon, director of the Stanford Sleep Epidemiology Research Center in Palo Alto, California, said one of the big strengths of the study is that it tracked changes in sleep among the same children as they aged.
"We have an evolution of the sleep during the childhood," said Ohayon, who was not involved in the study. "That is the unique thing."
Williams's team found that until their second birthday, babies in the study slept an average of 12 to 14 hours during each 24-hour period.
By age four that had dropped to about 11 hours of sleep and by age 10, to 10 hours. By age 16, kids were getting an average of about nine hours of sleep per night.
The findings suggest most kids' sleep habits are in step with government guidelines.
According to the CDC, toddlers should be getting 12 to 14 hours of sleep. Preschoolers should get 11 to 13 hours of sleep, and adolescents age 10 to 17 should get 8.5 to 9.5 hours.
The researchers didn't find any differences in the amount of sleep between boys and girls, and only a slight gap between white and Hispanic kids.
Hispanic children tended to sleep 19 minutes longer than white children after age nine, but Williams said that difference is too small to matter for individual kids.
Parent reports of how much sleep their kids get are not perfectly accurate, and they often can't describe the quality of sleep, such as whether kids wake up in the night. Williams said it's still possible individual children aren't sleeping enough, because the study could only measure reports of sleep duration, and not sleep quality.
Tracking sleep in a laboratory is more precise, but would cost too much for a study this size, said Ohayon.
He told Reuters Health the study still offers a good sense of how much sleep children typically get, which is valuable in helping to gauge whether a child has a sleep disorder.
"What we are hoping to do with these norms is give some sort of reference to be used by clinicians and parents to see if children fall far from average," said Williams.