Having technology such as televisions, smartphones and game consoles in the bedroom teaches the brain to see the room as an entertainment experience rather than a place for quiet and rest, they said.
Playing violent video games in the bedroom conditions the brain to see it as a place of danger, leading it to stay in a state of alert rather than resting, they added.
"One of the biggest culprits for inadequate and disturbed sleep is technology," Dalhousie researcher Jennifer Vriend, the study's lead author, said.
"Many teenagers sleep with their phones and they are awakened regularly by it ringing or vibrating throughout the night when they get a text, email or Facebook message.
"Having televisions and game consoles in the bedroom is also a problem," she said. "It sets up the brain to see the room as an entertainment zone rather than a quiet, sleepy environment."
Losing just one hour's sleep can reduce a child's performance at school, the study published in the Journal of Pediatric Psychology found.
"Even modest differences in sleep duration, accumulated over a few days, can affect critical cognitive and emotional functions in children," the study authors wrote.
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