Science now confirms what parents have long sensed: Children who are inactive during the day have more trouble falling asleep at night.
In fact, every hour of inactivity adds three minutes to the time it takes a child to fall asleep, a new study from New Zealand researchers has found. But children who are active during the day fall asleep faster and sleep longer, the researchers added.
"I believe that, in an environment that can offer technological toxicity to our children in the form of increased inactivity, this study reminds parents and clinicians alike of the importance of childhood exercise," said Dr. Robert Vorona, an assistant professor of sleep medicine at Eastern Virginia Medical School.
More and more data associates insufficient sleep not only with neuro-cognitive consequences but also with such conditions as hypertension, diabetes and obesity, Vorona said.
"This article demonstrates an association between increased levels of activity and a shorter time to sleep onset as well as the converse," he said. "The information is potentially important, and I do not find the association between activity and sleep latency surprising."
The report is published online July 23 in Archives of Disease in Childhood.
For the study, Edwin Mitchell, a professor of child health research at the University of Auckland, and his colleagues collected data on the sleep patterns and daytime activity of 591 children, all 7 years old.
On average, it took the children an average of 26 minutes to fall asleep, but the time ranged from 13 minutes to 42 minutes.
For the one in 10 children who found it difficult to fall asleep quickly, it took about 15.5 minutes longer to fall asleep, the researchers found.
Children who were active during the day took less time going to sleep than inactive children. And the more vigorous the activity, the faster they fell asleep, the study found.
But for sedentary children, every hour of inactivity increased the time it took to fall asleep by three minutes, Mitchell's group found.
About 16 percent of parents of school-age children say their child has difficulty falling asleep, according to the researchers, who noted that poor sleep patterns have been linked to poorer school performance and an increased risk of a child becoming overweight or obese.
"This study emphasizes the importance of physical activity for children, not only for fitness, cardiovascular health and weight control, but also for sleep," the researchers concluded.
Taking longer to fall asleep, though, is not really a problem, said Dr. David Rapoport, director of the New York University Sleep Disorders Centre.
"The finding goes with our biases," Rapoport said. "The more you run around as a child, the better you will sleep at night. But it suggests that if you don't do anything all day, you may need less sleep."
"It is not clear that if you don't do the exercise and don't get to sleep, or get less sleep, [that] is itself a bad thing," Rapoport said.
Is less sleep, then, something to worry about?
"Far from it," he said. "I see this as something which we were designed by nature to do. The purpose of sleep is to recover from activity, and what this is showing is that that link is quite tight in the child. If the child exercises, they need more sleep and they get it more easily."
For sedentary children, Rapoport said, the study indicates that they may be going to bed too early, when they are not ready to sleep.
"I don't know if there is a problem, but there is a simple cure," he said. "See to it that the kid gets enough exercise during the day because then they will fall asleep more rapidly." Steven Reinberg, HealthDay News