Having a smartphone or tablet next to us when sleeping is now a common occurrence. We know the light emitting from the phone interferes with our body’s circadian rhythms and makes it harder to fall asleep. But a new study has found that even having a device next to you and switched off can have a detrimental effect on our shut-eye.

The main focus of the study, conducted by a team from King’s College London, was the use of devices amongst children at bedtime. A child’s sleep is a crucial part of healthy growth but with the modern age, the distraction of mobile devices are reducing the needed length of sleep in young children and teens.

“Sleep is an often undervalued but important part of children’s development, with a regular lack of sleep causing a variety of health problems,” stated study leader Ben Carter from King’s College London. “With the ever growing popularity of portable media devices and their use in schools as a replacement for textbooks, the problem of poor sleep among children is likely to get worse.”

It’s no surprise that 72 percent of all children now have a mobile device and use it regularly before bedtime.

People may think the obvious solution would be to switch off the device before preparing for bed reducing the amount of exposure, but the study shows even having the device in the room, switched off or not, still has the same effect. It’s not quite known why this is but the team believe it’s down to a psychological effect and the “always on” nature of social media.

The solution may be to make a habit of always taking the device out of the room as kids who never have a device in their room reported less daytime sleepiness than those that did.

The study urges the importance of limiting exposure to smart devices around bedtime. The authors wrote: “It is imperative that teachers, health care professionals, parents, and children are educated about the damaging influence of device-use on sleep.” 

Details of the research was published in the journal JAMA Pediatrics.