Smartphones may reduce kids’ healthy sleep

Jan. 20, 2015—A smartphone—or another device with a small screen—in the bedroom can shorten a child’s sleep by as much as half an hour every night, according to a recently published study.

The study found children who slept near their smartphones went to bed later than kids without bedroom phones. Children with bedroom phones also felt significantly more tired during the school week.

Having a smartphone in the bedroom was even more disruptive to sleep than having a TV in the bedroom.

Big screens, little screens and sleep

The study involved 2,048 children who attended public schools in Massachusetts from October through December 2012. Most of the children—1,194—were fourth-graders and around age 9. The remaining 854 were in 7th grade and about age 12.

Slightly more than half of all the children said they kept their smartphone nearby when they slept—such as next to the bed or in the bed. And 75 percent said they slept in a room with a TV.

Researchers asked the children a series of questions about their sleep habits during the previous week, such as: When did you go to bed? When did you wake up? Did you feel rested the next day?

Compared to kids who didn’t sleep near a phone, children who slept near their smartphone slept an average of 21 minutes less every night. In addition, this group went to bed an average of 37 minutes later than children who didn’t sleep near phones.

Children sleeping near smartphones were more likely to feel increasingly unrested during the week than those who didn’t sleep with a phone. TVs weren’t significantly associated with kids feeling tired.

Why would small smartphone screens affect sleep more than big TV screens? One reason may be that TVs don’t beep, ring or play a short tune whenever a message arrives like a smartphone does.

Another possibility from the researchers: Screen light may interfere with the body’s release of the sleep-inducing hormone melatonin. Although TVs have a bigger screen, smartphones are held next to the face. The closer the screen light, the greater the interference.

Learn more about the research online in Pediatrics.

The take-home message
Children ages 5 to 12 need about 10 or 11 hours of sleep, according to the National Sleep Foundation (NSF).

The NSF recommends designating bedrooms a “no-screen zone,” no matter how big or small the screen may be. To help kids get enough healthy sleep, the NSF also suggests:

  • Limiting caffeinated drinks, especially late in the day.
  • Making sure that a child’s bedroom is sleep-friendly, which means dark, cool and quiet.


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