By Bonnie Rochman, TIME
The latest research on kids and sleep hones in on the biggest dream-robber.
Children are sleeping less, and there’s no shortage of reasons why: With television, video games, and the Internet, they are finding it harder to shut down and go to sleep. Over the last century, the time children spend asleep has declined by more than an hour. But which factors are most responsible for keeping kids awake?
In a study published in the journal Pediatrics, researchers in New Zealand surveyed more than 2,000 children and young adults aged 5 to 18 about their activities over a 24-hour period. The scientists were interested in learning whether children who went to bed earlier engaged in different activities than those who went to sleep later, and focused on what the children did in the hour and a half before bedtime. The participants listed everything from eating, getting ready for bed, reading, and completing homework, to watching television, playing video games, and listening to music.
Television was the most common pre-bedtime activity, accounting for 30 of the 90 minutes analyzed on average. And it was also the major reason children stayed up; those who fell asleep later watched 13 more minutes of TV than those who turned in earlier. Watching television also made it harder for the children to fall asleep; the more time they spent in front of the screen, the longer it took them to drift off.
“We know that children sleep less than they used to,” says Louise Foley, who was a research fellow at the National Institute for Health Innovation at the University of Auckland when she conducted the study. “The general consensus is that they’re going to bed later, not that they’re getting up earlier.”
Previous studies have pointed to the stimulating effects of television in shortening children’s nightly slumber, but this analysis is among the first to focus specifically on what children do just before bedtime. Not only is television stimulating for the brain, keeping watchers alert rather than allowing them to start shutting down for the day, the lights from the screen may also act as a biologically based wake-up call. “There is a suggestion that TV affects sleep hormones because screens emit blue light and that could delay sleep onset,” Foley says. Blue light may keep the circadian clock set to the wake, rather than sleep, cycle.
“Most guidelines for watching television recommend a maximum of two hours for young people,” Foley says. “If you consider that they’re watching 30 minutes in the 90 minutes before bed alone, they’re likely exceeding that two-hour recommendation.”
But how much is too much? If 30 minutes of screen time just before bed is keeping children awake, would 20 minutes still rob them of too many z’s? “Nobody has really come up with a certain amount of screen time, a threshold that might disrupt sleep,” Foley says.
Still, the results do suggest that limiting television just before bed might help children to get to sleep faster. Turning off all electronics as bedtime approaches could also help sleep as well — even if that’s becoming more unrealistic in our media-obsessed society.
This article was written by Bonnie Rochman and published in TIME on January 16, 2013.