Why screen time in bed – not before bed – is the serious sleep stealer

Fresh findings from University of Otago researchers suggest taking screens to bed is bad for sleep.

• University of Otago study found teens’ screen use in bed impairs sleep more than pre-bed screen time.
• Researchers used body cameras and actigraphs to monitor screen time and sleep among 85 adolescents.
• Gaming and using multiple devices in bed significantly reduced sleep duration among participants.

A new study that fitted teens with body cameras at night has changed what we’ve long assumed about screen time before bed.

While health guidelines tend to recommend no screens in the hour or two before bed time, the just-published findings suggest the worse problem for young people is taking their screens into bed with them.

That emerged after University of Otago researchers used body cameras to monitor evening screen time among 85 participants aged 11 to 14.

A second infrared camera was also placed in their bedrooms to capture their screen time while in bed, while a watch-sized device called an actigraph measured their sleep.

“It quickly became obvious that adolescents spend a lot of their screen time while in bed,” study lead author Dr Bradley Brosnan said.

Virtually all of the young people used screens in the two hours before bed, more than half also used screens once in bed, and a third watched them after first trying to fall asleep.

“Our most interesting findings were that this screen time before they got into bed had little impact on sleep that night,” Brosnan said.

“However, screen time once in bed did impair their sleep – it stopped them from going to sleep for about half an hour and reduced the amount of sleep they got that night.”

That was especially true for more interactive screen activities such as gaming and using multiple devices.

“Every additional 10 minutes of this type of screen time reduced the amount of sleep they got that night by almost the same amount.”

University of Otago researchers Dr Bradley Brosnan and Shay Ruby-Wickham used these body cameras to measure evening screen-time habits among nearly 80 adolescents. Photo / University of Otago

The findings also suggested that, rather than being disrupted by blue light or interactive use, the participants’ sleep was mainly affected by it being delayed.

Brosnan said a simple sleep guideline would be for devices to be kept out of the bedroom.

“We need to revisit sleep guidelines, so they fit the world we live in and actually make sense – the current ones aren’t achievable or appropriate for how we live.”

The findings come after researchers last year warned too much screen time in childhood – Kiwi kids are estimated to look at devices for 23 minutes of every hour outside school – is linked to poorer health in adulthood.

Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.