The quality of sleep, closely related to the time spent on a screen

Teens who spend a lot of time in front of screens (televisions, computers, tablets, mobile phones, game consoles), sleep less and have more trouble falling asleep, according to a study published Tuesday.

Carried out on 10,000 young Norwegians aged 16 to 19 years old, the study showed such screens more addicted adolescents had increased risk to more than an hour to fall asleep.

This risk is increased by 49% of those using a screen for more than four hours per day (outside school hours) compared with those using it for less than an hour.

The risk was maximum for those watching their screens in the hour before sunset, according to the study published in the medical journal BMJ Open online.

Studied were on average need 8 to 9 hours of sleep to get in shape the next day, but those who spend more than two hours to send emails or "chatter" on the internet were three times more likely to sleep less than five hours per night.

The researchers also found that those who used multiple devices in the days had more difficulty falling asleep and slept less time than those using only one device.

Those using two or three devices had thus 50% likely to sleep less than five hours a night than those using a single device. For those using four or more, the risk was increased by 75%.

For researchers, led by Dr. Mari Hysing Research Center of health in Bergen (Norway), it is high time that Governments are updating recommendations on screens that concerned only the TV for a long time.

"The results (of the study) confirm the need to recommend the restriction of the use of the media in general," they added.

They advance the hypothesis that screens stimulate the nervous system and that the light emitted is involved in circadian rhythms (or biological rhythms), which has a negative effect on sleep.