Exposure to computer screens and other electronic devices is disturbing the sleep of teenagers, a new study has shown.
More than 95% of US teenagers have at least one electronic device in the bedroom with most reporting using it before the go to sleep at night. At the same time, reports of poorer sleep quality and overall reduction in hours of sleep are emerging among adolescents.
To find out whether the two might be linked, Mari Hysing from Uni Research Health in Bergen, Norway, questioned jsut under 10,000 Norwegian 16-19 year olds about their daily screen and gadget use as well as their sleep behaviour and any complaints of insomnia or poor sleep quality. The data, published this week in the BMJ, reveal a striking trend.
"There's a dose-dependent relationship," says Hysing. "The more screen exposure an individual has, the more likely they are to be sleep-deprived or to have trouble dropping off to sleep."
Almost all of the teenage respondents in the study reported using an electronic device in the hour before they went to bed, and on average they each notched up between 5 and 7 hours of screen exposure per day. Individuals with the highest levels of documented time in front of a screen during the day were one-and-a-half times more likely to report difficulty dropping off at night, while those reporting five hours' sleep or less were nearly four times as likely to be the heaviest users of computers during the day.
The impact could be dramatic, counsels Hysing. "In a previous study we found that teenagers are losing out on 2 hours sleep every single day."
The team speculate that the bright light from the screen is partly to blame. "The blue light they emit can disturb the hormones of sleep. It puts back your body clock, making it harder to fall asleep."
The data also show that chatting online is a risk factor for disturbed sleep. "This can be very stimulating and brain activating," says Hysing. "And if you're activating your brain you are not relaxing ready to sleep."
The team don't advocate necessarily banishing mobiles and computers from the bedroom, "but these findings are certainly something to think about. People might want to pay more attention to relaxing properly before they go to bed to be sure of a good night's rest.&qu