Parents the world over have been worrying about whether their children get enough sleep for more than a century, a new study shows.

The study also found that, even as recommendations about how much sleep kids need have changed since the late 1800s, studies have shown that kids get less sleep than recommended.

“We were surprised that over the last century, the actual amount of sleep that children are getting was consistently about 37 minutes less than what was recommended for them,” said lead study author Lisa Anne Matricciani, of the University of South Australia in Adelaide.

And for the last 100 years, “modern living” has been blamed for robbing kids of shuteye, according to the research. The bedtime-delaying culprits have changed with the technologies of the time, from the electric light bulb and the radio in the earlier parts of the 20th century, to the social media and video games of today.

The study is published today (Feb.13) in the journal Pediatrics.

Recommendations vs. actual sleep

To explore the historical trends in sleep recommendations, and compare them to data on the actual amount of time children and teens were sleeping, Australian researchers collected information and studies dating from 1897 to 2009.

They found 32 sets of age-specific sleep recommendations for children, and more than 200 articles that reported on how much actual sleep children got.

The advice by experts of how much sleep children and teens need tend to exceed what kids really get by roughly 30 minutes, whether the year was 1908 or 2008. Although age-specific sleep recommendations declined over the century, the actual amount of sleep that children got declined at a nearly identical rate.

Insufficient sleep in children has been linked with poor academic performance, an increased risk for obesity, higher rates of drug and alcohol use and more frequent injuries.

“The rationale for sleep recommendations was also strikingly consistent for more than 100 years — that children were overtaxed by the stimulation of modern living,” Matricciani said.

But what she and the research team found most remarkable was that there was almost no solid, empirical evidence to support the sleep recommendations being made for children.

“This is not to say that kids don't, in fact, need more sleep, just that the evidence is not out there,” said Timothy Olds, a professor of health sciences at the University of South Australia, who also worked on the study. Sleep recommendations may reflect ingrained biases — that kids are sleep-deprived or the world is going too fast — more than good science, he said.

Perhaps parents “should take sleep recommendations for children with a grain of salt,” Olds suggested.

Watch your child

The best way for parents to determine if a child is getting enough sleep is to “watch your child, and not the clock,” said Dr. Marc Weissbluth, an expert on childhood sleep problems and a professor of pediatrics at Northwestern University Feinberg School of Medicine in Chicago.

In his book, “Healthy Sleep Habits, Happy Child” (Ballantine Books, 1999), Weissbluth does not offer sleep recommendations, but instead tells parents to observe certain signs and symptoms.

Look at a child's mood, personality and performance near the end of the day, he advised. If your child is under age 3 and napping, look at them between 4 p.m. and 5 p.m.; for a child age 3 or older, look between 5 p.m. and 6 p.m.

Is your child sweet, adaptable and well-functioning, or short-fused, clingy and irritable? This can tell parents whether a child is well-rested or overtired, and whether naps or bedtimes need to be adjusted, Weissbluth said.

Weissbluth said that even though there might be an absence of evidence about exactly how much sleep children need this shouldn't leave parents with the impression that kids are getting enough shuteye.

Rather than focusing solely on the number of hours a child sleeps each night, he advises parents to focus on how a child appears near the end of the day, and when sleep is occurring.

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